Apri11973 25p

SURVEY: DISC CUTTERS AND TAPE COPIERS

SOUND '73 PREVIEW
LOW-LIGHT TELEVISION

1 1 1 1 1 1 1 1 I 1 1 1 1 1 1
 CREATIVE SUCCESS....

Console designed for This console was supplied 32 into 8,

Soundpush -CMS Studios, wired for up- dating to 32 into 16
Blaricum, Holland. considering future studio expansion.

Whatever the recording

Automatic function selection by push- button control
of the audio systems, including complete sync facilities
eliminating the need for multi- switching in order to change
over from normal recording into overdubb or re -mix.

ada Cadac (London) Limited

STANSTED ESSEX ENGLAND Tel: Stansted 3437 & 3132

MANUFACTURERS OF AUDIO CONTROL EQUIPMENT FOR THE SOUND RECORDING INDUSTRY

studio sound
INCORPORATING TAPE RECORDER

EDITOR DAVID KIRK

ASSISTANT EDITOR JOHN DWYER APRIL 1973 VOLUME 15 NUMBER 4

ADVERTISEMENT MANAGER TONY NEWMAN

AUDIO GROUP ADVERTISEMENT MANAGER WOULD YOU ENCOURAGE your son to enter the sound
ROBIN WELLS
recording industry? Probably not, since present working
conditions make it one of the least secure vocations in existence
AMERICAN REPRESENTATIVE STEPHEN H. LAMPEN -second only to cinematography.
The first serious step towards improving the status of record-
Editorial and Advertising Offices: LINK HOUSE, DINGWALL ing engineers took place at Lansdowne Studios on January 31.
AVENUE, CROYDON CR9 2TA. Telephone: 01 -686 2599 An inaugural meeting of the Engineers Guild was chaired by
the president of the Association of Professional Recording
American Office: P.O. Box 99569, San Francisco, Studios, Jacques Levy. One of the Guild's first acts was to bite
California, 94109, U.S.A. off their own head by declaring that they would not be involved
©Link House Publications Ltd 1973. All rights reserved. in trade unions, politics, conditions of work, or rates of pay.
'These things,' Mr Levy claimed, are provided elsewhere'.
Indeed? Then `elsewhere' has totally neglected its duties.
CONTENTS The one trade union with any interest in this industry, the
ACTT, is recognised by only a few of the larger studios and
virtually none of the many small ones. Few junior studio staff
FEATURES receive any formal training, few are allocated reasonable
working hours, few receive more than token wages, and few
OPTU- ELECTRONIC AUDIO LEVEL DISPLAY enjoy even the security of a used -car salesman. The majority
By Rune Espelien 35 work in conditions tending to cause premature deafness.
SOUND '73 PREVIEW 44
Why do youngsters tolerate these limitations? Attracted by
what they consider an alternative to the commercial rat -race,
DISTORTION: CAUSE AND EFFECT they find themselves instead in the thick of it. And since every
Part Two opening faces a queue of other keen souls to replace any
By Tony Eden 50 disillusioned junior, the tendency is to remain as long as sanity
and a hard -pressed love of music allow.
THE dBm OR THE dB(V)? The Guild desire to see sound recording recognised as a
By Angus McKenzie 54 profession, a latterly devalued term defined as (1) an employment
not mechanical and requiring some degree of learning; (2) a
SURVEY: DISC CUTTERS 56 religious belief or pretence. Which definition they choose must
SURVEY: TAPE DUPLICATORS 60
depend largely on their attitude to formal technical training.
The Tonmeister concept has not exactly been welcomed in this
COLUMNS country, despite capable work by the University of Surrey, so
what will the Guild suggest as an alternative? Some kind of
NEWS 22 recognised qualification, whatever its level, would in the long
term be more profitable than the present system resting on vague
NEW EQUIPMENT 24 `studio experience' and actually meaning 'jobs for the boys'.
LETTERS Qualifications can indeed be a disadvantage under present
28
conditions as one Oxford graduate in physics discovered
PATENTS recently when sacked by a studio manager fearful of being
By Adrian Hope 30 ousted by his junior. And this was no back -street studio.
Mr Levy and others are known to fear trade union involve-
DIARY ment in the recording industry. To quote the words of the
By John Dwyer 36 APRS president on an earlier occasion, `eventually they'll say
it takes 14 people to operate a desk'. Admittedly many unions
VIDEO: MARCONI XQ1402 LOW -LIGHT TUBE have displayed the most deplorable contempt for the general
By Roderick Snell 40 public but this is all the more reason for a presently union -free
industry to put itself in order.
REVIEWS
INFONICS 102 CASSETTE COPIER COVER
By Hugh Ford 72 Kodalith photograph of a Neumann cutting lathe at EMI Abbey Road,
from an original by Tim Bishopp.
CORRESPONDENCE AND ARTICLES SUBSCRIPTIONS
All STUDIO SOUND correspondence should be sent to the address STUDIO SOUND, publishedmonthly, enables engineers and studio
printed on this page. Technical queries should be concise and must management to keep abreast of new technical and commercial
include a stamped addressed envelope. Matters relating to more than one developments in electronic communication. The journal is available
department should occupy separate sheets of paper or delay will occur without charge to all persons actively engaged in the sound recording,
in replying. broadcasting and cinematographic industries. It is also circulated by paid
Articles or suggestions for features on all aspects of communications subscription to manufacturing companies and individuals interested
and musical engineering will be received sympathetically. in these industries. Annual subscription rates are £3 (UK)
Manuscripts should be typed or clearly handwritten and submitted with rough or £3.30 ($8 or equivalent) overseas.
drawings when appropriate. We are happy to advise potential authors STUDIO SOUND is published on the 14th of the preceding month
on matters of style. unless that date falls on a Sunday, when it appears on the Saturday.

BINDERS PAST ISSUES

Loose-leaf binders for annual volumes of STUDIO SOUND are A small number of certain past Issues may stillbe purchased from Link
available from Modern Bookbinders, Chadwick Street, Blackburn, Lancashire. House, price 31p each including postage. Photostat copies of any STUDIO
Price is 85p. Please quote the volume number or date when ordering. SOUND article are available at 25p including postage.

10111/4111III
STUDIO SOUND, APRIL 1973 3
Budget priced spendor
compact The "New standard in loudspeaker
cassettes design is now even better

from 26p
Low Noise
Guaranteed
Screwed
Not Welded
Library Case
Prices 10 100
Spendor introduce the BC
1
I II
POST& PACKAGE C60 29p 28p 26p
1 -10 cassettes 10p C90 39p 37p 35p
11 -100 cassettes 25p C120 52p 46p 44p Nominal impedance 8 ohms
Price per cassette Frequency response 22dB 50Hz -14kHz
Frequency range 30Hz -20kHz
VAT not included Power rating 70watts peak programme
These prices are liable to alteration without notice. Units Spendor 12"
Spendor 8"

fpa

`
Fraser - Peacock Associates Ltd Celestion HF1300
94 High St. Wimbledon Village Celestion HF2000
London SW19 01.9471743,/2233 Dimensions 314"x154'x151"
Weight 701b
Price On application
Registered Office:94 High St Wimbledon Village London SW19
*John Shuttleworth, 'Studio Sound', September 1970
PLEASE SEND ME CHEQUE /PO. FOR
C60 C90 C120

NAME
Spendor Audio Systems Limited
ADDRESS
Kings Mill Kings Mill Lane South Nutfield
. .

II Redhill RH1 5NF . Phone Nutfield Ridge 2554

.

Registration No 779084(England)
 The current complexity and prohibitive Direct Selling
cost of multichannel recorders has Our policy of direct selling
previously deterred the musician from together with large scale
utilizing the full potential of a professional production is obviously reflected
recorder as a creative medium. in our selling price of £492. To
Nice 'n' Easy ease any financial burden we have
negotiated with U.D.T. the
At the touch of a button it is lowest terms currently available.
now possible to produce L.P. quality
masters or demos in the relaxed Curtains
atmosphere of your own studio for The end of the studio is nigh ?
under £500. Certainly not, since the introduction
Comprehensive of this recorder is creating a new
generation of recording studios.
The Industrial Teac is so comprehensive
that such tapes may be produced with only
a pair of headphones, a microphone and
a mixing lead.
D &D
Delivery immediate to your door -
Demonstrations to studios within 150 miles of
London.
Low Multitrack Noise
The fact that we have broken the Domestic version available at £465.
-63dB noise and £1000 price barrier is no Complete MINI STUDIO around £1100.
coincidence. A -63dB noise level coupled NEW LOW TAPE PRICES
with absolute simplicity is creating a new We can offer Scotch 207 3600 ft. at 25% BELOW
generation of smaller recording studios. TRADE PRICE for moderate quantities.

Sole U.K. Distributor

INDUSTRIAL TAPE APPLICATIONS
105 High Street, Eton, Windsor, Berks.
Tel: (95) 52663
STUDIO SOUND, APRIL 1973 5
 NEW equipment for the
professional soundrecording
studio from brii..iI
DESIGNED AND MADE IN THE U.K.
MULTI -CHANNEL EQUIPMENT
We have set a new price/performance standard with our 4, 8 and 16 channel studio
recorders offering full facilities for the production of master recordings. PPM or VU
meters on each channel. Equalisation to CCIR, NAB and IEC characteristics. Remote
control for tape transport and record functions. The equipment is in full production and
studio use in both U.K. and overseas.

STUDIO RECORDERS
for 2- channel reducing, field recording and full -track mastering.

re
TAPE TRANSPORTS
We offer a widened range of 2 speed and 4 speed models from 15/16
to 60 IPS, á" to 1" tape width, with heavy duty solenoid operation and
remote control facilities.

b
BRENELL ENGINEERING CO LTD
11
231 -5 Liverpool Road, London N1 1LY Tel. 01 -607 8271 (5 lines)

See and hear the world's finest Audio Equipment at:

Britain's Premier Hi -Fi Audio Exhibition

0 NEM13 Excelsior Hotel, London Airport (Heathrow)

Wednesday 28 March to Sunday 1 April inclusive from 11 am

Tickets and posters for you and your clients may be

obtained from B.A. P. Ltd, 31 Soho Square, London
W1 V 5DG Car Parking Free coach service from
Sonex 73, the 4th International Exhibition sponsored by the Hounslow West Underground Special Audio Features
Federation of British Audio, 31 Soho Square, London W1V 5DG and technical presentations

6
HS77 I5-7
The high speed Revox is firmly
established as standard equipment in
the majority of London Theatres,
Local Radio Stations, and Recording
Studios

PRIDE f230
Delivered to your door

SEL SYNC +120

IMMEDIATE DELIVERY

SOLE U.K. SUPPLIER

VHS77 30-IS
WIDE BANDWIDTH 40 Hz -40 KHz of
particular interest to research establishments
TAPE DUPLICATION The equalisation
characteristics 17.5 and 35 Sec are such
Fs.

that a 1:1, 2:1 or 4:1 speed ratio will produce

a copy tape of the same recording charac-
teristic as the master
HIGH TAPE VELOCITY of 30 ips (76
ems) is invaluable for the analysis of data
and transient information
TAPE ECHO 50 milli seconds or 100
milli seconds
Delivered to your door
LE
1298
IOS HIGH ST., ETON,

.T.A.
for
WINDSOR, BERKS.
Tel. WINDSOR (9S) S2663
Contact Barry Lambden for further information
London's most competitive rates
Finance available through UDT only 92 %

REVOX Subject to increase after 1st April '73

NEW LOW TAPE PRICES
We can offer Scotch 207 3600 ft. at 25% BELOW TRADE
REVOX HIRE PRICE for moderate quantities

STUDIO SOUND, APRIL 1973 7

 EVERY NUN NEEDS
a SYNTHI
Electronic Music Studios (London) Limited
49 Deodar Road London SW 15 01-874 2363
New York 408 East 78th Street N.Y. 10021 USA

The Synthi Range by EMS

A GOOD ALL ROUNDER AUDIO CONNECTORS
BROADCAST PATTERN JACKFIELDS, JACKCORDS
PLUGS & JACKS. QUICK- DISCONNECT MICROPHONE
CONNECTORS. AMPHENOL (TUCHEL) MINIATURE
HM80 CONNECTORS WITH COUPLING NUT. HIRSCHMANN
Hybrid BANANA PLUGS & TEST PROBES. XLR COMPATIBLE
IN -LINE ATTENUATORS. LOW COST SLIDER FADERS
Module approx. BY RUF.
actual size FUTURE FILM DEVELOPMENTS LTD.
This general purpose Hybrid AC control module. It provides a dynamic
is a
90Wardour Street WIV 3LE
control range of 80 db and it is capable of performing any function that lies
between the frequencies of 3 Hz and 200 KHz. 01 -437 1892'3
Furthermore it will operate with single supply voltage ranging from 4.5 to 24
Volts with negligible variation of all other characteristics except of course the
maximum input and output voltage swing which is mainly determined by the
supply voltage.
This miniature encapsulated 24 pin Dual -In -Line module contains also all the
necessary coupling and decoupling capacitors and therefore the external WE SPECIALISE IN BRAND NEW
components are limited to those necessary to perform the individual function
required. TOP QUALITY BRITISH P.V.C. MYLAR & POLYESTER
The internal pin connections have been specially arranged to make the design
of printed circuit boards very easy and the module will plug into a standard 24 RECORDING TAPES WITH FITTED LEADERS, Etc., EX 3"
pin D.I.L socket for maximum flexibility.
The outstanding quality and reliability of this module makes it ideal for use in Thanks to bulk purchase we can offer tensilised HI -F1 tapes, manufactured
the professional field and along with the specification sheet comes a very by a British firm of world repute. All boxed individually (sealed if required) in
comprehensive application report dealing with all aspects of sound recording polythene. Our tapes are not to be confused with imported sub -standard or used
equipment. tapes. Full money refund if not delighted.
Furthermore we undertake to design free of charge any application required This month : -"DRY SPLICE" (19p) given FREE with every order.
but not listed in the application report.
Std. L.P. D.P. Boxed
For further details write or phone:
Length ea. 3for Length ea. 3 for Length ea. 3 for empty spis
3' 150' 10p 29p 3" 220' 12fp 35p 3" 400' 223p 65p 3" 3p
4" 300' 20p 50p 4" 450' 25p 70p 4" 600' 34p 97 }p 4" 8p
APOLLO ELECTRONICS 5"
5r
7"
600' 30p 87 }p 5" 900' 40p
900' 35p EI.02+ 5 }" 1200'52 }p
1200'45p El .27¡ 7" 1800'65p
LI.17+
0521
El 92¡
5"
51"
7"
1200'62 }p LI.85
1800'85p E2.50
2400'El.05 E3.05
5"
5
7"
*"
9p
9p
lop
96 MILL LANE, LONDON NW6 INQ All orders despatched by return. Postage and Packing 9p per order

Telephone: 01- 794 -8326 STARMAN TAPES, 421 Staines Road, Bedfont, Middlesex
Amcron
FmLIpIErs Amcron, you will recognise world- renowned Crown International
In
amplifiers- beyond all question, the best of their kind
in the world. Only the
product name has been changed to avoid any possible confusion of identity.
The range shown here will meet the needs of studios, groups, theatres,
and indeed wherever power is demanded with the absolute maximum quality and
reliability.
All quoted output powers are Root Mean Square values.

D.60 the 100 watt amplifier

Two channel extra -compact power amp. In stereo-40 watts per channel at clip
point into 8 ohms; 62 into 4 ohms; in mono, 100 watts into 8 ohms. At 30 watts
per channel into 8 ohms power response is -±-1 dB from 5 to 30,000 Hz,
THD is below 0.05, and hum and noise 106 dB below. Built -in protection against
mis -use. Input sensitivity 0.75V into 25 Kohms. Size 17in x 81in x 11in high.

D.150 the 330 watt amplifier

Two channel model. 100 watts per channel at clip point into 8 ohms. 140 watts
into 4 ohms loads. 330 watts into 8 ohms used mono. Power response
±1 dB from 5 to 20,000 Hz at 75 watts per channel into 8 ohms. THD less than
0.05°,. Damping factor greater than 200 up to kHz. Hum and noise 110 dB
1

below at 75 watts per channel into 8 ohms. Input sensitivity 1.19V +2% into
25 Kohms for 75 watts out. Built -in protection against mis -use. Size
16Zin x 5in deep x 8in high, less front panel (Front panel optional extra, £15).
19in rack mounting fittings also available. Price, less front panel

DC.300A the 1,000 watt amplifier

Power at clip point (per channel) 200 watts into 8 ohms: 350 watts into 4 ohms:
500 watts into 2.5 ohms. Used mono -greater than 650 watts into 8 or 4 ohms.
This new unit will operate into loads as low as ohm and no longer
1

requires protection tuses as did its predecessor the DC 300.

Power response +1 dB from zero to 20,000 Hz at 150 watts per channel
into 8 ohms. Total harmonic distortion 0.02°,ó at 300 watts
per channel into 4 ohms. Hum and noise below 110 dB at 150 watts
per channel into 8 ohms. IM distortion 0.05°,ó from 0.01 watt to 150 watts per
channel into 8 ohms. Input sensitivity 1.75V for 150 watts out per channel into
8 ohms. Size, with front panel, 19in x 7in x 9111in (suitable for standard rack
mounting).

M.600
Single channel power amplifier. 600 watts into 8 ohms or 1,000 into 4 ohms with
THD less than 0.1 °;,. Frequency response f1 dB from zero to 20 kHz.
Two M.600s can be linked to give a massive 2,000 watts into 8 ohms. With built -in
automatic two -speed cooling and protection devices against mis -use. Weight
- _ 80Ibs nett. Size 19in x 81in high x 161,in (standard rack mounting).
w
'0 I
Amcron amplifiers carry a three years' warranty on materials and
labour. Full descriptive leaflets gladly sent on application.

MACINNES LABORATORIES LTD. STONHAM, STOWMARKET. IP14 5LB.

Telephone Stonham (044 971) 486.
STUDIO SOUND, APRIL 1973 9
 MYC kC-2 PRIORITY

Pictured here, the PRO A120, one of PRO A120 Professional PA Amplifier
the three new professional PA amplifiers Output Power: 120 watts RMS
Eagle have in store for you this year. Frequency Range: 35- 20,000 Hz.
This one has an RMS output power of
120 watts behind it. And there's a 65 watt
200 uV '
Inputs: Mic 1: Hi 5 mV @ 50,000 ohms or Lo
200 ohms (using PPLZ).
Mic 2: 5 mV @ 50,000 ohms.
amplifier and a 35 watt mains /mobile Mic 3: 5 mV @ 50,000 ohms switchable
model too. to Magnetic Phono: 4 mV () 47,000 ohms (RIAA)
All three have 100 volt balanced line Mic 4: 5 mV @ 50,000 ohms.
Aux /Tuner: 400 mV @ 100,000 ohms.
outputs as well as 4, 8, and 16 ohms. Signal to Noise Ratio: Better than 75 dB.
All three have a priority page circuit Output Impedance: 4, 8 and 16 ohms and 100
which preempts all music and other voice volt line output.
transmission. Operating Voltage: 220 -250 volts AC.
They all function as mixers too.And Dimensions: 350 x 130 x 310 mm.
List Price: £125.00 (excl. VAT)
there are slide controls and memory
markers on each for easy operation.
Have a look down our list of
specifications and see just how many other PRO A65 Professional PA Amplifier
Output Power: 65 watts RMS
features we've included. Frequency Range: 40- 20,000 Hz.
Could be you'll find the price tag Inputs: Mic 1: Hi 5 mV @ 50,000 ohms or Lo
something of an attraction too. 200 uV @ 200 ohms (using PPLZ).
 ...
illllll

MASTER VOLUME

Mic 2: 5 mV @ 50,000 ohms. Output Impedance: 4, 8 and 16 ohms and 100

Mic 3: 5 mV @ 50,000 ohms switchable volt line output.
to Magnetic Phono: 4 mV @ 47,000 ohms (RIAA) Operating Voltage: 220 -250 volts AC or 12
Aux /Tuner: 400 mV @ 100,000 ohms. volts DC.
Signal to Noise Ratio: Better than 70 dB. Dimensions: 350 x 130 x 310 mm.
Output Impedance: 4, 8 and 16 ohms and 100 List Price: £75.00 (excl. VAT)
volt line output.
Operating Voltage: 220 -250 volts AC.
Dimensions: 350 x 130 x 310 mm.
List Price: £95.00 (excl. VAT)
Eagle International°
Eagle International Precision Centre Heather Park Drive
Wembley HAO 1SU Telephone 01 -903 0144
PRO A35 Mains /Mobile Professional PA
Amplifier
Output Power: 35 watts RMS Please send me your catalogue containing
Frequency Response: 50- 18,000 Hz. details of the new Eagle Professional
Inputs: Mic 1: Hi 5 mV 50,000 ohms or Lo Amplifiers and.other P.A. Equipment.
200 uV @ 200 ohms (using PPLZ).
Mic 2: 5 mV @ 50,000 ohms. Name
Mic 3: 5 mV @ 50,000 ohms switchable Address
to Magnetic Phono: 4 mV @ 47,000 ohms (RIM)
Aux /Tuner: 400 mV @ 100,000 ohms.
Signal to Noise Ratio: Better than 70 dB. L_ ss?I
 Now Altec speakers systems and stereo components are designed
to offer you finer specifications for better listening and the
available latest features for better control of what you hear and the
in the U.K. - newest innovations for professional recording studios.
the world And that's why we say they're built a little better.
renowned
ALTEC
LANSING
range.
Bolita little better

For further details

write to sole
U.K. Distributors:
ACOUSTICO
ENTERPRISES LTD.,
6-8 Union Street,
Kingston- upon- Thames,
Surrey. Tel. 01 -549 3471/3
(3;l i n e s).

3{:] AUpODESGNR.ECJRpINt+
IttR (onrReSSOR{.nNpER /sox -R

THRESHOLD RELEASE RATIO PEAK LIMIT

I \ /

iNPVT OUTPUT EXPANDER COMPRESSOR

o
STEREO STEREO
INPUT
s< 1,
OUTPUT

THRESHOLD RELEASE RELEASE RANO PEAR LIMIT

F760X -RS STEREO LIMITER -COMPRESSOR -EXPANDER

It's all here -every facility you've ever required in the field of level
control- expansion, compression and limiting; stereo matched to
obviate image shift during operation. Eliminate increased noise due
to compression; reduce channel noise, studio cross -talk and ambi-
ence. Available on short delivery in both modular and rack formats.

8, AUDIO DESIGN RECORDING

TEL: READING (0734) 84487
ST MICHAELS
SHINFIELD ROAD
SHINFIELD GREEN
READING BERKS UK

12
 A J 1i1A

Sound design by
Comprehensive facilities for multi-track recording
triad
combined with functional design and performance
beyond reproach, add to this a price tag that will not
break any hearts, and the result is aTriad `B' series
console. Available with any number of input
channels, and normally supplied with 8 group
outputs and 16 track monitoring, two foldback, four
echo routes, full equalization and complete access at
large jackfield. If this isn't enough, theTriad Ä series
offers just about the most complete specification
available, and can now be supplied fully automated
for maximum versatility.
CREAM
TRIAD A
FOR ENGINEERS DT CNGINEERJ
Trident Audio Developments Limited 4 -10 North Road, London N7 9HG
Telephone 01 -609 0087 Telex, 27782
 An example of the Midas
modular system mixers.
Medium scale chassis, with space for sixteen inputs. The input modules
shown include, sensitivity control and fader, pan and
output group switch, fold back with pre- fade /post -fade
switch, bass, treble, presence equalisation and reverb/
echo mix.

The top level has four output modules with PPM

calibrated Vu Meters and compressors.

The middle level accommodates the fold back output,

talk back and headphone facilities, acoustic compensation
filters and triple range crossover network. The lower level
also includes a send and return panel.

Specifications
Inputs 0.2 mV into 200 ohms, 10 mV into 50K ohms.
Outputs normally OdbM into 600 ohms.
Overload range 60 db, low and high Z, channel outputs 16 db above Odb,
Vu indication.
Line outputs Max level + 16 dbM
Signal to noise Ratio At maximum channel gain 66db,Typically 80db at normal
gain settings
Distortion Less than 0.1% THD

Midas Professional Amplication. 87, North Grove, London, N.15. Telephone 01 -800 6341

ELECTROSONIC-
Designed and manufactured
the integrated sound, lighting
and projection system at the
HARDROCK, MANCHESTER
The Hardrock Control Console
is shown on the left.

ELECTROSONIC-
Will be pleased to supply
a specification for any
project large or small.

ELECTROSONIC-
Have supplied lighting and
projection systems for:
Emerson Lake and Palmer
Pink Floyd -The Who -Yes-
-
The Rolling Stones- Family
King Crimson.
-

ELECTROSONIC
Electrosonic Limited Electronic Control and Audio Systems
815 Woolwich Road London SE7 9LT
Phone: 01 -855 1101 Cables: Multiplex London SE7
14
all you need
is the plug

we supply the rest!

for a complete portable recording studio

LAMB LABORATORIES
PRESENT THEIR MINI -STUDIO
COMPRISING
A REVOX A77 high speed tape recorder with Sel Sync,
variable pitch and illuminated remote control unit.
PLUS
The LAMB 4 channel stereo mixer with in -built com-
pressors-Full channel equalisation -Pan Pots and echo
send controls.
The mini -studio kit is completed by 4 Beyer microphones
and 4 stands (2 with booms) -Beyer DT100 headphones
Power Supply- Carrying cases -and ALL interconnecting
-
leads.
Remember, all you have to supply is the plug!
If you can't make it to Sonex, just fill in the Coupon
DURING SONEX '73
and we'll provide all the operating instructions and
If you're visiting Sonex, see the LAMB Mini -studio at our Hospitality the specifications you'll need to have your own
Suite. At the beautiful Skyline Hotel -where you can also readily
park, dine and be entertained. Simply take one of our scheduled
mini -buses (which will return you to the Sonex venue) 400 yards
------------ - - ---I
completely Portable Mini -studio. Post it to -day!

Detailed information on Mini-studio/Mixer

down the road and enjoy the superb facilities of the Skyline. NAME
March 28, 29, 30, 31 9.30 a.m. to IO p.m.
ADDRESS

LAMBL ) s0M ;','a y

Lamb House,Church Street Chiswick, London W4 2PB
Telephone 01 -995 4551. Telex 934047. Cables Lambex London TELEPHONE SS43

STUDIO SOUND, APRIL 1973 15

 "The alternative to
QUAD
is not a
colour television set
but a seat
in the
concert hall"

QUAD
for the closestapproach to
the original sound

Send postcard for illustrated leaflet to Dept SS

Acoustical Manufacturing Co. Ltd., Huntingdon, Tel: (0480¡ QUAD is a Registered Trade Mark.

16
The ubiquitourlf1153.

The Shure SM53 professional unidirectional microphone is seen with increas-

ing frequency in the best of company because it affords eight distinct perform-
ance advantages: (1) a wider front working angle with uniform tonal quality;
(2) effective noise rejection through a true cardioid pickup characteristic: (3)
a built -in shock mount for effective mechanical noise isolation; (4) extraor-
dinary ruggedness for performance consistency after severe shocks; (5) a
superior hum rejection system: (6) an integral breath "pop" filter; (7) a min-
imized proximity effect for constant tonal quality; and (8) full field serviceability.
Interested?

Shure Electronics Limited

84 Blackfriars Road
London SE1 8HA. England H
STUDIO SOUND, APRIL 1973 17
 a LJ_lix
SOUND SYSTEMS AND ELECTRONICS

010.AR AUDIO bp

The MXT -800 series of audio mixing modules can be Overall mixer specification:
supplied to form compact 2 or 4 group mixers suitable for
Frequency response: ±0.4dB 20Hz -20KHz including
use in local broadcast and the smaller recording studios.
Each mixer is custom built and can incorporate P.P.M. input and output transformers.
or V.U. metering, and additional master output group, Distortion: Typically 0.02% at normal levels.
limiter, talkback, monitor, echo, oscillator, pan, and line Less than 0.1% 20Hz -20KHz at
equaliser modules. +18d B m.
Noise: Microphone channels: noise
factor less than 2dB ref. 600 ohms.
All other inputs: -75dBm.
Gain: Maximum system gain,
microphone 100dB.
Line 20dB.

MANUFACTURERS OF AUDIX BB LIMITED

SOUND SYSTEMS AND STANSTED ESSEX
ELECTRONICS TELEPHONE: STANSTED 3132/3437 (STD 027 -971)

18
 WHEN STUDIOS CONSIDER
A TOP QUALITY
DYNAMIC MICROPHONE ...

... IT'S STILL THE AKG 202

_!J.lt.i
"iw
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7ü
iati.ia
ar
try Ilk
d

!I!!!
!/.....f- l,ir,
..,..r411
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Demonstrations without obligation available on all
AKG professional microphones and reverberation units.

FOR FULL INFORMATION CONTACT:

AKG EQUIPMENT LTD.

182/4 Campden Hill Road
Kensington London W8 7AS
Telephone 01.229 3695.

STUDIO SOUND, APRIL 1973 19

 The perfect companion to your Nagra recorder!

SELA
professional mixer

£336

write or phone for spec sheets

SOLE UK DISTRIBUTORS
CINTRON GROUP
GROVE HOUSE 551 LONDON ROAD
ISLEWORTH MIDDLESEX
TEL 01/568/0131 TELEX 935054

COMMUNICATION ACCESSORIES &

EQUIPMENT LIMITED
77 AKEMAN STREET, TR1NG, HERTS, U.K.
G.P.O. Type components on short delivery
JACK PLUGS -201, 310, 316, 309, 404
-
JACK STRIPS
JACK SOCKETS
PATCH PANELS
--
310, 320, 510, 520, 810
300, 500, 800, B3 and B6 mountings
made to specifications
LAMPS & LAMP STRIPS - SWITCHBOARD No. 2 LAMP CAPS 10 way PO 17 20 way PO 19 BALLAST PO No.
HOLDER No. 12
I I

CORDS, PATCHING & SWITCHBOARD

-- made to specifications

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TERMINAL BLOCKS DISTRIBUTION 20 way up to 250 way
LOW PASS FILTERS type 4B and PANELS, TELEGRAPH 71 (15 x 4B)
UNISELECTORS various types and manufactures both PO and miniature
LINE TRANSFORMERS /RETARDATION COILS
- - type 48A, 48H, I49H, 3/16, 3/216, 3/48A, 3/43A, 48J, etc

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PO TYPE KEYS 1000 and PLUNGER TYPES 228,279, etc
19" RACKS VARIOUS SIZES

Telephone: Tring 3476/8 STD: 0442 -82 Telex: 82362 Answerback: Batelcom UK Tring

20
 The simple case for using
Scotch MagicTransparent Tape
Ordinary transparent adhesive tape Scotch Magic Transparent Tape

Very visible. Ordinary tape makes a very visible Almost invisible. Magic Transparent Tape is
join and spoils the appearance of the item. much less obvious. It tones in with the background
so the join becomes almost impossible to spot.

Difficult to write on. J ecause of its shiny Easy to write on. Magic Transparent Tape is
surface ordinary tape is difficult to write on. easy to write on- ballpoint and pencil reproduce
perfectly. You can type on it too.

"Ghost" effect on copies. Ordinary tape gives "Ghost- free" copies. You get perfect copies
a ghost effect on copies and photographs making with Magic Transparent Tape. The taped section
the subject underneath difficult to read. is just as legible as the rest.

79,4 rg rg;r r
2 rg2

Non -permanent. Ordinary tape shrinks and It's permanent so it won't shrink, discolour
yellows with age leaving an unsightly black line or peel off. Magic Transparent Tape isn't
round the edges. It also tends to crinkle and peel affected by sunlight. moisture or temperature
off if exposed to moisture. change. It stays just the way you stick it down
no matter how long you leave it.

If you would like a free sample of Scotch Magic Transparent

"rape, fill in this coupon and send it to: Commercial Trades
Marketing, 3M United Kingdom Ltd., 3M House, Wigmore
Street, London, W1A lET.

Nam,.
Company
you Kotre lhe /mpftf1efroen. Pos-itiml

Nottke pe.
Address

SS'4 73 n
m mark.
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STUDIO SOUND, APRIL 1973 21

Nixon administration attack public commited perjury. The records do not justify were no objections from the IBA lawyers'. The
television the attribution of perjury to him.' Councillor IBA had apparently stopped the program
A PLAN to strip the American Public Broad- George said he spoke with knowledge of primarily because they felt it should have given
casting Service of its responsibility for program family papers not shown to any outsider since certain people mentioned in the Poulsen
production and scheduling was disclosed before the 1914 -18 war. bankruptcy proceedings more opportunity to
recently by the board of the Corporation for defend themselves against statements made in
Public Broadcasting. This presidentially court and reported in the film. However, such
appointed body intended to restrict the network Sir Lew Grade bans ATV documentary an opportunity had in fact been extended to all
to relaying programs among the 232 public AN 80 MINUTE documentary film about Michael those mentioned in the film (excluding Mr
television stations. Announcing the plan, Mr Collins, an IRA leader killed 51 years ago, has Reginald Maudling and Mr John Cordle who
Henry Loomis (CBP president) indicated that been banned by Sir Lew Grade from trans- had already declined to make public state-
he had the support of the Nixon Administra- mission in the United Kingdom. The £10,000 ments). The majority had declined.
tion whose disapproval was aroused by film was written and narrated by the Welsh On February 5, production staff connected
discussion programs such as 'Washington Week actor, Mr Kenneth Griffith, who agreed that with the documentary were supported by other
in Review' which the Administration consider his film might 'inflame strong passions'. Mr Granada, Thames TV and Midlands ATV
`too liberal'. The Administration were also Griffith considers the British Government of staff in a 30 minute television blackout as a
keen to see the removal of Mr William Buckley, the day to have been responsible for the trend protest against the IBA ban.
a strongly `right wing' broadcaster who had in of events in Northern Ireland. His film
turn criticised Mr Richard Nixon's policies as criticised Lloyd George, Winston Churchill
being 'too liberal'. and Eamon de Valera for their actions at the
Mr Loomis denied that the Nixon Admini- time.
stration had given way to pressure from
commercial broadcasters. He admitted that,
prior to becoming president of the Corporation Taste and standards
Public Broadcasting last November, he had `TASTE AND Standards in BBC Programs' is the
never watched a public television program. title of a pamphlet issued by the BBC to all it
The chairman of the Public Broadcasting producers during February. The 11 page guide
Service, Mr Robert Schenkkan, has since discusses cases of bad language assumed to
commented that the decision would not be have given offence to viewers and listeners .

acceptable to the licensees. Other PBS repre- selecting as examples: bl * *dy, bl* *ding and
sentatives added that the dispute might G *d. These, the pamphlet declares, have
eventually have to be resolved by Congress. different meanings for the older and younger
generations. An example of 'excessive nudity'
was given as a scene in the historical series
Elizabeth R; a naked girl leaving the bed of the
IBA asked to preview sexual education King of France. Portraying the bedroom
series habits of monarchs in the Tudor period was
THE INDEPENDENT Broadcasting Authority have
considered to contribute little to historical
been asked to preview a Granada Television The Maple Leal -four
series `The Facts Are These' scheduled for
understanding.
broadcast to schools during 1973. The series,
produced for children of 15 and 16, includes Granada abandon Poulsen documentary Value added tax
education in venereal hygiene and contracep- AFTER HAVING their 60 minute documentary READERS ARE reminded that prices quoted in
tion. The complainant, a Mrs Mary White- 'The Friends and Influence of J. L. Poulsen' this issue may become subject to Value Added
house, commented: 'It would appear from banned twice by the Independent Broadcasting Tax from the beginning of April.
statements in the press that the producers are Authority, Granada finally withdrew the 76
starting from the assumption that premarital production at the end of January and began
sex is more or less normal'. preparing a new and updated version. This was
to be presented to the IBA during March. Mr
Denis Forman, joint managing director of
Attempt to bar BBC play Granada, said Granada's lawyers (Goodman
ATTEMPTS BY relatives of David Lloyd George Derrick & Co) `passed the program as suitable
to obtain an injunction against a recent after the closest scrutiny that I have ever seen a
television play failed to satisfy the Attorney program subjected to, and we understand there
General. The play was produced for the BBC 2
series 'The Edwardians' and was criticised by
the former prime minister's nephew, councillor
William George. Although he had not actually A Nigerian student training in educational
watched the play, he felt: 'The author relied on broadcasting techniques at the London
completely inadequate sources and was histori- studios of the Centre for Educational
Development Overseas. A Leevers-Rich
cally very inaccurate. Most attention has been E200 is being used to produce a tape
concentrated on my uncle's morals, and alleged program for children. Most of the CEDO
association with women. I am surprised that students are qualified teachers and receive
the point has not been raised which stuck most instruction in script-writing, presentation, editing
in my gullet. This was the suggestion that Lloyd and system operatic n. Courses last from
George, with the knowledge of his wife, ten days to 16 weeks.

22
geta bit more.
472 Functions (Gain, switch and position control)

100 Millisecond scan rate

Bi -phase digital encoding with SMPTE time coding

compatibility.
Exclusive Leveloc updating facility

VCA resolution + .1 dB (0 -45dB)

Dropout and splice immunity (Buffer memory)

Expandable and fully compatible function encoding

Tape machine speed variation tolerance ±15%

Compumix.
mixdown
system

J a.r J d i v d i qr9 , a: a. Q..40..Y,...

J1'1. JJDgg8868888888á-
,
.; $ á í a if á s á

I 1 1 1 1 1 1 1 I Ill 1,Iqt\

Quud /Iqh[ onIcs

11929 Vose Street North Hollywood. California 91605 213/764 -1516
 NEW EQUIPMENT

Variable speech rate unit Audio modules

LEXICON OF Massachusetts are making a device A NEW SERIES of audio modules is now being
which provides pitch-independent time control manufactured by Key Electronics. They are
of recorded speech and can be used to constructed on 89 x 64 mm glass-epoxy printed
synchronise a script in any situation. Voice circuit boards and are available in completed or
signals are recorded on a cassette and then kit form. M1C- A /St/1 is an fet input stereo
converted into digital signals. These are passed microphone amplifier selling at a basic £15.20
through circuits which compress or expand completed and tested. Above ten off, the price
them, after which they are reconverted to falls to £12.90, from 25 off to £11.60, and from
analogue form. The speed of speech can thus 100 off to £10.65. The kit starts and ends at
be varied between 0.5 and 2.5 times that of the £8.50.
original with a frequency range of 50 Hz to Comparable price structures relate to the other
11 kHz. The equipment measures 356 x 330 x five modules. Type MIX/St /i is a 10 + 10
152 mm, weighs 8.2 kg, and will operate from input unity gain stereo mixer at £7.70. Type
50 or 60 Hz mains at 110/230V. VU/GPA /St/i is a stereo VU drive and general
Agents: F. W. O. Bauch Ltd, 49 Theobald purpose amplifier at £5.40. The LDA /i is a
Street, Boreham Wood, Herts WD6 4RZ. 600 ohm line drive amplifier offering up to +19
dBm output at £8. A ppm driver to BBC
FIG.1 VC SQUARE WAVE OSCILLATOR specification, the PPM.1a costs £17 excluding
Hybrid audio module movement. Lastly, TC /St/1 is a modified
AN AC CONTROL module with a wide variety of Baxandall stereo tone control ( ±12 dB at 100
suggested applications is now being produced Hz at 10 kHz) at £11.45.
by Apollo Electronics. The HM80 module is Manufacturers: Key Electronics, 16 Gains-
compatible with a standard 24 pin DIL is borough Road, Queens Park, Bournemouth BH7
socket and operates from 4.5 to 24V negative 7BD, Hampshire.
ground. Gain may be varied across 80 dB with
±0.5 dB linearity within the control range. CONTROL
I PUT
OUTPUT

Total harmonic distortion under normal 0 10+3V

operating conditions is specified as 0.1 per cent, Multiposition slide switches
frequency response being 3 Hz to 200 kHz ±0.5 R3 A RANGE OF slide and pushbutton switches
dB. Application reports (available on request) manufactured by Jeanrenaud is now being
include measuring equipment, subsonic Alfa marketed by ITT Europe. Model CL6 offers up
wave amplifiers, microphone and tape ampli- to six positions as single pole two, three, four,
fiers, equalisers, telephone simulators and FREQUENCY CONTROL RANGE ....110 five or six way; two pole two or three way; or
voltage controlled filters. Fig. i shows a FOR C =1000pF, 5= 1-10KHz three pole two way. The CL12 similarly offers
suggested vc square wave oscillator configura- FOR C = 0.015F f = 100Hz -1KHz a maximum of 12 positions in all formats
tion and fig. 2 a compressor /limiter giving up R1....113K.R2....10N,R3._.100K
between single pole 12 way and six pole two
to 20 dB compression. RI. 10K LOG. OUTPUT LEVEL CONTROL way. Versions with 3 lim gold on brass contacts
Manufacturers: Apollo Electronics, 96 Mill 01....2X3820 FET
are available for industrial applications, with a
Lane, London NW6 1NQ. specified life of 50,000 operations. For other
purposes, silver -plated brass contacts offer a
FIG. 2 15,000 operation expectancy. Also in the
O TO 20dB COMPRESSOR LIMITER
Budget videotape Jeanrenaud range, 19 x 19 mm switch modules
WITH THE basic price of 12.5 mm videotape available with push and push /push actions. The
still around £10 per 730m, considerable interest TFB module has a maximum rating of 20 mA
may be aroused by Dixons announcement of at 24V dc, insulating resistance being at least
Dixtec CCTV tape at £5.50. Quality is claimed 10,000M ohms.
to be equal to the dearer brands. Agents: ITT GC Europe (EPD), Edinburgh
Agents: Dixons Technical Ltd, 3 Soho Square, Way, Harlow, Essex.
London WL

High power Spendor Sela mixers and Advent cassette

A LARGER AND more powerful monitor loud- recorders
speaker has been introduced by Spendor: the SELA MINIATURE audio mixers, designed to
BC3. Measuring 800 x 400 x 400 mm, the new operate directly from Nagra recorders, are now
model is rated at 70W peak program and has a FREQUENCY RESPONSE 20Hz -20KHz being distributed in Britain by Cintron. Manu-
nominal impedance of 8 ohms. Frequency THRESHOLD LEVEL__- 10dBm,250mV factured in Sweden by Svenska Elektronik, the
COMPRESSION RANGE... 20dB
range is 30 Hz to 20 kHz (50 Hz to 14 kHz ±2.5 GAIN BELOW THRESHOLD_.. UNITY Sela 2880 has four inputs to suit balanced
dB). Four units are incorporated, 304 and 203 OUTPUT LEVEL AS LIMITER... OdBm capacitor or dynamic microphones (50 to 200
COMPRESSION RATIO....1:1
mm diameter Spendor drivers plus HF1300 and TO LIM.

MINIMUM OPERATING SUPPLY_ .9V DC

ohms) and can also be switched to 0 dB line
HF2000 .Celestions. The BC3 is expected Rl....L7K, 82....1.55. R3....100K (10k ohms). Output is two channel feeding the
to cost £150. 01.02....2N3820 FET Nagra (50 mV into 2.5k ohms) or program line
TI....GARONERS MU7526 OR EQUIVALENT
Manufacturers: Spendor Audio Systems Ltd, 01,0233,01.... TI 1544 SILICON DIODES (3V into 600 ohms). Equalisation comprises
Kings Mill, Kings Mill Lane, South Nuffield, Al_..5K LOG. COMPRESSION RATIO CONTROL ±10 dB at 100 Hz and 10 kHz (2 dB steps)
R5.. 1M LIN RELEASE O.1 - 5 SEC
Redhill, Surrey. 26 )10.

24
 Sansui. the grandmaster of the stereo -world: jus
made three new bold moves. The EIGHT. The SEVEN.
The SIX. Moves which get Sansui once more into
the forefront of imaginative audio engineering. These
new items unite, for the first time, the outstanding
characteristics of different type components
resulting in an astonishing high level of versatility
and performance.
For detailed and free information on these new
Sansui items please contact the addresses below.
Continuous Power Total Harmonic FM Sensitivity
Sansui RMS power at 8n Bandwidth( HF) distortion Selectivity
(IHF)
EIGHT 60/60 watts 10- 40.000 -lz less than 0,3% 1,7v.V better than 60 dB
SEVEN 47/47 watts 10- 50.000 -tz less than 0,3% 1,8!V better than 60 dB
SIX 39/39 watts 10- 50.000 Hz less than 0,3% 2 p.V better than 60 dB S(Z.IZSZLL

EIGHT SEVEN SIX

r
England: VERNITRON LTD., Thornhill Southampton S09 OF - Tel.: Southampton 44811 Ireland: INTERNATIONAL TRADING GROUP LTD., 5 Cope Street.
Dame Street Dubl r. 2
la-Reme r
Vv, COMPO HI -Fl G.M.B.H., Re wng ris 6 Frankfurt ark Main
,
. J
France: HENRI COTTE & CIE, 77 rue J -R. Thorelle. 77 92- Bourg-
Luxerkbowg LUX HI-FI, 3 rue Glesener "MI Austria: THE VIENNA HIGH FIDELITY &STEREO C °, Burggasse 114- 1070 Wien 70 Belgium: MATELECTRIC S.P.R.L.,
-

Boulevard Léopold II, '99 - 1080 Brussels

! Netherlands: TEMPOFOON N.V., Kapitcin Halterastraat 8, Posthus 540- Tilburg C Greece: ELINA LTD., 59 & 59A Tritis Septem-
vriou Street Athens '03 H' Italy: GILBERTO GAUDI s.a.s., Corso Di Porta Nuova 48 - Milano LI Norway: FRIGO NORSK A.S., Eitert Sundtsgatan 40 - Oslo 3
-
J
Sweden:
MAGNETON, Sveav_gen 61 - 113.59 Stockholm r.Denmark:.OUALI-FI INGENI0RFIRMA, Christiansholms Parkvej 26 - 2930 Klampenborg n Finland: AUDIOVOX OY -
Kornetinhe 2 Helsinki 38 L: Cyp'us: ELECTROACOUSTIC SUPPLY C° LTD., P.G. Box 625 - Limassol Ci Portugal: CENTELEC LDA, Avenida Fontes Pereira
-
de Melo 47,
- 1 -
J
4.odto Lisboa 1-1 Malta: R. BRIZZI, 293 Kingsway Valletta LI Switzerland: SONOVOX AG, Wallstrasse 11 - 4051 Basel Canary Islands: R. HASSARAM, Calle la Naval 87
Las Palmas South Africa: GLENS (PTY) LTD., P.O. Box 6406 Johannesburg
- J
SANSUI AUDIO EUROPE S.A., Diacem Bldg, Vestingstraat 53/55 - 2000 Antwerp, Bel-
gium LI SANSUI AUDIO EUROPE S.A. FRANKFURT OFFICE, Reuterweg 93 - 6 Frankfurt am Main West Germany
uçinami-ku - Tokyo 168 - Japan
J
SANSUI ELECTRIC C° LTD., 14.1, 2- chome, Izumi,

STUDIO SOUND, APRIL 1973 25

 NEW EQUIPMENT Automated cinema projector
AN AUTOMATED PROJECTION system based on a
16 mm Elf--Lire projector has been developed
with low -pass filtration at 20 kHz (-5 dB) and by Clewer Audio Visual Services. Initiated
32 kHz (-18 dB). A speech filter provides 18 dB from a single pushbutton located in the
per octave cut below 100 Hz. Dimensions are manager's office or the auditorium, the system
360 x 320 x 550 mm. The 2880 weighs 6 kg and follows a preset sequence to dim house lights,
costs £336. mask the screen, fade background music and
Cintron are also handling the Advent 201 commence sound and picture. On completion
two channel cassette recorder. This employs of a 21 -hour film, the projector rewinds the
a Wollensak tape transport and Dolby B noise film in 25 minutes ready for a subsequent
reduction system and sells for £165. program.
Agents: Cintron, Grove House, 551 London Suppliers: Clewer Audio Visual Services Ltd,
Road, Isleworth, Middlesex. Suwiley House, 466 Bath Road, Slough,
Buckinghamshire.

Visual track analyser

SELLING AT £8.95, the Willis Magna-See kit Acoustic alarm
comprises a tin of magnetic fluid, a developing A HIGHLY PENETRATING audio signal, either
bath, magnifying lens, tape cleaning fluid, and frequency or amplitude modulated, is produced B12/400S raises 12V dc to 115 and 230V 50 Hz,
a reel of low -tack tape. After a recorded tape by the Cybertone audible warning unit. 400W maximum. The C24/500S accepts 24V
has been immersed in the bath, and surplus Equally suitable for fixed or portable applica- dc and produces 500W. Each unit incorporates
fluid allowed to evaporate, magnetic powder is tions, the 40 x 46 mm unit is entirely self- a low level stable oscillator followed by an
deposited on the recorded tracks which are contained and is described as highly reliable intermediate amplification stage feeding into
then rendered visible. The powder may output transistors.
subsequently be removed or transferred to Manufacturers: Valradio Ltd, Browells Lane,
paper by means of the low tack tape. Feltham, Middlesex TW13 7EN.
Manufacturers: Willis Computer Supplies Ltd,
PO Box 10, Southmill Road, Bishop's Stortford, Four channel headphones
Hertfordshire. ACOUSTIC RESEARCH have been appointed UK
agents for Superex, the second largest US
manufacturers of headphones. Of particular
Ppm boards interest in the Superex range is the model
FIBREGLASS PRINTED circuit boards for the peak QT-4B four channel headset incorporating four
program meter circuit described by Hugh acoustically isolated and electronically indepen-
Walker in our January 1973 issue are now dent elements. If the principle seems open to
available from Surrey Electronics, 24 High question, Superex are unequivocal: `True four
Street, Merstham, Surrey. The 70 x 65 mm channel sound, with even more spatial drama
boards are fitted with gold plated eight -way than stereophones offer'. The QT-4B, as
edge connectors and cost 75p. Complete kits illustrated, employs conventional ear clamping
for the ppm driver are available at £8, including configuration and weighs 455 gm. Other head-
six cermet trimpots, six 5 per cent zeners, four phones in the Superex range are the PEP77D
BC109C and the gold edge connector. Surrey mains electrostatic (£56), PEP79 self-energising
Electronics also offer the circuit assembled and electrostatic (£39.90), and a series of seven
tested at £12. Suitable meters are 600 ohm 1 moving -coil models.
mA left hand zero such as the Ernest Turner since it does not employ make /break contacts. Agents: Acoustic Research International, High
642-PPM at £9. All prices include postage and Operating voltage is 12V dc at 20 mA and Street, Houghton Regis, Bedfordshire.
packing. temperature tolerance is -20° to +55 °C.
Manufacturers: A. P. Besson Ltd, St Josephs'
Close, Hove, Sussex BN3 7EZ.
Linear vca
NEW FROM dBx, the 202 voltage controlled
amplifier comes encased in a 50 x 25 x 12.5 mm Filter module
can with 3 mm gold-plated printed circuit A NEW AUDIO frequency filter has been
board pins. Gain varies from -100 to +30 dB announced in the USA by Spectra Sonics.
depending on the applied control voltage. Model 506 can provide three separate outputs
Excellent linearity and unit -to -unit tracking are from a single input signal, using external
claimed. Input noise is specified as 6µV with switching. Two configurations are available,
peak signal levels up to 100V, 20 kHz band- the high pass 506H filtering below 40, 70 or
width and 0.07 per cent distortion. 100 Hz. Model 504L passes below 10, 12.5 or
Manufacturers: dBx Inc, 296 Newton Street, 15 kHz. Quoted frequencies are -3 dB points,
Waltham, Massachusetts 02194, USA. rolling off at 18 dB per octave. Card dimensions
are 64 x 127 x 13 mm and the US price $69.
Manufacturers: Spectra Sonics, 770 Wall t.
Avenue, Ogden, Utah 84404, USA.

Dc /ac transvertor
TWO NEW transvertors from Valradio: models
B12/400S and C24/500S. Both are to sell at
£197 and have a frequency stability better than
+0.25 Hz at 50 Hz. They are described as
suitable for industrial video recorders, film
cameras, audio recorders and small computers,
up to a loading not exceeding 500W. Model
26
 A 3 -head, 30-20,000 Hz, 24 Watt,
4 -track stereo, semi-professional,
x95 let -down.

Specifications. Price. Performance. These are Grundig flywheels and capstans and motors
the factors you compare before you buy audio are built to precise tolerances. Yet we quote a best wow
equipment, aren't they? But there's seldom and flutter figure of as much as ± o. i °,. Much better,
any way of checking reliability. Which is why too we think, than quoting less - and having an independent
many enthusiasts, who should know better, end up less than lab. discover several 'oval' capstans in a batch !

enthusiastic about the 'bargain' they've made. Grundig recorders have no gimmicks, but good
At Grundig we don't believe in publishing fancy reliable mechanism, tape cleaners, and robust, positive
figures. We'd rather our machines lived up to their and accurate controls.
specifications - and continued to do so. And sophisticated circuitry, with
For instance our published top minimal discrepancy between
end response is i 6,000 Hz. stereo channels.
But i 6,000 Hz it'll stay, long after So whichever Grundig you
less hard -headed machines have buy, it'll give you a lot more than
worn down. Our output power figures to impress your
rating is continuous rms power. friends.
And sounds it. Eight models to choose from.

The difference is incredible

Grundig (Great Britain) Ltd., London, SE26 SN l

STUDIO SOUND, APRIL 1973 27

 LETTERS

The Ambiguous Watt raggedness of response, if not in general aversion to using these standards, which lay
Dear Sir, I wholeheartedly agree with your balance. (See `What Price Loudspeaker down methods of measuring and expressing
Editorial in the December issue on the Response Curves ?' by Ralph West, Hi-Fi News the result of, among other things, manufac-
`Ambiguous Watt'. & Record Review, September 1971.) When we turers specifications. In case anyone should be
A letter is not the place to enlarge on whether eventually have a method of measurement motivated to look at them, the reference
the phrase `rms Watts' has any meaning at all which is: (1) definitely repeatable; (2) may be numbers are BS3860, BS2489, BS4850 and
but, assuming that most people use it to mean applied to all loudspeakers; and (3) is not open BS4054. (Tuners will be included in a supple-
average Watts, one may legitimately ask to reasonable dispute-then we shall start ment to BS4054 to be published probably in
whether average Watts are an appropriate publishing frequency response curves with our 1973.)
measure of the output capabilities of an reviews. It may be objected that these specifications
amplifier or of the input capabilities of a loud- Regarding impedance curves, I confess that are not internationally accepted and there is
speaker. My own opinion is that, except for we had not assumed our readership to be so some truth in this, for, if UK engineers do not
very specialised applications (for example ignorant as to confuse electrical impedance at promote their use, who will? There is no such
using an amplifier to drive a capstan motor or the terminals with frequency response in the air, reticence on the part of our German counter-
using a loudspeaker in sound insulation but Mr Shuttleworth's fears may apply in some parts. DIN standards themselves are not easy
measurements), one is not interested in the cases and we are now adding a warning note to to use for two reasons. One is that they are
maximum average performance of the device. the curves. Our thanks for this suggestion. rarely self-contained, making many cross-
The really vital factor is that the amplifier Impedance curves are not, I would suggest, references to other DIN standards. For a full
should not distort for the largest instantaneous quite as pointless as Mr Shuttleworth implies. use of the well -known DIN 45.500, for instance,
power outputs demanded by the signal. I Modern speakers frequently descend to 3 ohms about 120 other DIN standard documents are
suspect that a workable measure could be built or less at some frequencies, and in consequence required, excluding test records and tapes, and
up from consideration of the point where more than a few amplifiers are not able to give some of these documents appear to be per-
perceptible (to be defined carefully in an Inter- of their best. Also, the phase-shifts in consumed manently in draft form and not generally
national Document) voltage (or current) slip- current arising from reactive loads (represented available. Also, many are only available in
ping occurs. Let us say that this point gives by steep slopes on the impedance curve) can German and anyone who has seen the mess
values of output voltage (or current) swing sometimes do curious things even with highly even quite a competent non -technical translator
(peak) of U (or 1), then if the load is R we can respected amplifiers, a fact discovered to every- can make of a technical document will under-
call the peak output U2 /R (or 12R). A similar one's puzzlement and distress at several audio stand what that implies. Anyone unconvinced,
argument can be carried out for loudspeakers. exhibitions. Amplifiers are not yet by any who has access to IEC documents, might look
I am carrying out some experiments on power means as perfect as is commonly imagined- at 29B (Germany) 20. The translation here was
amplifiers to see what sort of numbers come unless working into a 10 ohm pure resistance! almost certainly under strict technical control
out when one uses a criterion like the above, Yours faithfully, John Crabbe, Editor, Hi -Fi but there are things you can write in German
and also to see if a long -term average (say one News & Record Review, Link House, Dingwall that are nonsense in English.
hour) power rating would be necessary as well. Avenue, Croydon CR9 2TA. It may also be suggested that some of the
In the meantime let us all try to give up BSI standards are out of date. Again, there is
using Watts -no qualifications at all', `Watts, some truth in this and the reason is that the
speech and music,' `Genuine rms Watts' (sic), International Electrotechnical Commission are
`Music power,' `Watts rms delivered to a load,' Loudspeaker impedance
Dear Sir, One point John Shuttleworth failed gradually publishing two massive Recom-
and `Watts Programme' to list only a few mendations, Publications 315 (covering all
quoted in your December issue. to mention in his December article on loud-
speaker measurements: Despite the tendency types of radio receiver) and 268 (sound system
Yours faithfully, J. M. Bowsher, University of equipment), together with corresponding docu-
Surrey, Guildford, Surrey. to regard DIN standards as inadequate, in the
area of speaker impedance tolerances they are ments concerning tape and disc players as units
[We are not responsible for advertisement copy! rather than system components. When these
-Ed.] really quite tight. In fact all the speakers
mentioned-Spendor, Rogers and the Quad are published in full, or nearly so, the appro-
ESL-would probably fail to meet it !
priate BSI committees will consider bringing
Yours faithfully, Reginald Williamson, Bay the corresponding British standards into line
Pointless Curves? with the IEC recommendations, as is normal
Dear Sir, As editor of a `consumer audio Cottage, 18 Unthank Road, Norwich NOR
28E. BSI policy.
magazine' whose loudspeaker reviewing policy Regarding `The Ambiguous dBm', the
seems to fit the description offered by John situation was further changed at the recent
Shuttleworth in his article Loudspeaker IEC SC29B meeting in Oslo, and the critical
Measurement Parameters (December), I would Specifications wording in Publication 268.2 is to be changed.
like to comment on his remarks. There are two Dear Sir, Your December issue Editorial is The basic reason for this is that abbreviations
separate issues involved: the usefulness or concerned with a subject about which I feel for units are the responsibility of IEC TC25
otherwise of electrical impedance curves, and fairly strongly. I am a confirmed supporter of and it is that committee who cannot accept the
the extent to which a measured frequency properly informative and accurate specifica- `dBm' abbreviation, quite apart from the
response may be misleading. tions, and a pre- requisite of these is a standard- confusion explained so clearly by your distin-
On the latter, I happen to believe that loud- ised system of methods of measurement. It is guished contributors. The chairman of TC25
speaker design at its best has now advanced to not generally recognised in this country that attended the SC29B meeting and, after much
the point where objective measurements of these already exist for audio equipment, at discussion, the `V7' proposal was not accepted.
response can correlate quite well with subjective least for amplifiers, loudspeakers and now The only admissible expression was `dB
assessments of overall tonal balance. The record playing units, as well as radio receivers (0.775V)'. Those who support the dB(V) as a
remaining doubts here concern the variety of and soon radio tuners. I find it very surprising preferred reference feel that the very clumsiness
ways in which measurements may be made, that, in spite of the work put in by industry, of the expression will cause it to fall into disuse.
each `legitimate' and with its own rationale, consultants and the staff of the British Stand- Yours faithfully, J. M. Woodgate, 28 Adelaide
but all giving different results in terms of ards Institution, there appears to be a positive Road, Chislehurst, Kent BR7 6BB
28
 Response
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STUDIO SOUND, APRIL 1973 2
 PATENTS

THE FOLLOWING list of Complete December 13, 1972 vibrato signal AKG Akustische U Kino -Gerate GmbH
Specifications Accepted is quoted 1303808 1304533 Capacitor microphone
from the December and January issues Plessey Co Ltd Zenith Radio Corporation 1305305
of the Official Journal (Patents). Copies Speech analysers and synthesisers Chroma amplifier for a colour receiver Licentia Patent -Ver- Waltungs -GmbH
of specifications may be purchased at 1303867 1304554 Uhf communication systems
25p each from The Patent Office, Matsushita Electric Industrial Co Ltd RCA Corporation 1305307
Orpington, Kent BR5 3RD. System for processing music to produce Liquid crystal display device RCA Corporation
a tremulant effect 1304564 Reduction of tape stiction
1303945 S -Atlas -Werke GmbH 1305331
Mattel, Inc Magnetic tape cassette recorder Sony Corporation
Disc record drive 1304594 Magnetic recording and reproducing
December 1304030 Western Electric Co Inc apparatus
6, 1972
1303021 Libbey- Owens -Ford Co Acoustic optic devices 1305359
Sansui Electric Co Ltd Antenna type windshields and methods 1304606 GABR, S Z M
Sound reproduction system of producing them Western Electric Co Inc Arrangements for cancelling feedback
1303036 1304050 Single sideband modulation using 1305456
Akai Electric Co Ltd Philips Electronic á Associated digital filters Heil O
Video tape recorders Industries Ltd 1304613 Electroacoustic electromagnetic
1303054 Circuit arrangement for producing a Kolbe!, G F transducer
Freeman, marker in a television image System for the presentation of a visual 1305480
R J and Freeman, H
Information reproducing system 1304061 display with accompanying sound Siemens AG
1303119 Hitachi Ltd 1304637 Stearable antenna arrays
Sony Corporation Chrominance signal generator having Columbia Broadcasting System Inc
Magnetic recording and reproducing a patterned filter Scanning apparatus
1304648
December 29, 1972
apparatus 1304091 1305506
1303181/2/3/4 Staar SA Prall Modling Co Inc
Musical instrument
ITT Industries Inc
Computer Optics Inc Tape recording and /or playback Differential pressure units
Display systems apparatus 1305622
1303203 1304104 December 20, 1972 Dolby Laboratories Inc
AKG Akustische U Kino -Gerate GmbH Philips Electronic & Associated 1304774 Signal compressors and expanders
Reverberation system Industries Ltd Palmer, W W 1305635
1303207 Receiver tuning arrangements Tone control circuits Sony Corporation
Brown Boverì & Co Ltd 1304118 1304801 Video signal generating apparatus
Electron tube protection apparatus AKG Akustische U Kinogerate GmbH Tesla Narodni Podnik 1305683
1303268 Apparatus for producing artificial Electrostatic spiral transducer International Standard Electric
Socias, A reverberation 1304910 Corporation
Cassette tape recorders 1304134 Standard Telephones & Cables Ltd Internal delay stabilisation device for
1303277 Nippon Electric Co Ltd Pulse regenerator equalisation transponder
Bell & Howell Co Magnetic recording - reproducing 1304929 1305735
Power transmission mechanism system International Business Machines Multitone Electric Co Ltd
1303423 1304210 Corporation Communications systems
Booth, B H Texas Instruments Inc Meth ,d and apparatus for synthesising 1305801/2
Aid for the teaching of music Target scanning camera vocal sounds General Electric Co
1303518 1304213 1304988 Information storage using a conductor -
Sonicaid Ltd Handland (Photographic instrumen- Siemens AG insulator- semiconductor structure
Ultrasonic detection instruments tation) Ltd, John Echo compensation circuits 1305819
1303602 High speed cameras 1305075 Post Office
Shackman, A 1304221 Mullard Ltd Method and apparatus for detecting a
Loudspeaker assemblies Eastman Kodak Co Electromagnetic horns speech signal in the presence of noise
1303612 Film snubber for a sprocketless 1305100 1305891
Brown Ltd, S G and Ibbotson, T D motion picture projector Borg -Warner Corporation Bolkow, L
Ear defender headsets 1304268 Recording systems System for radio transmission of
1303621 Standard Telephones & Cables Ltd 1305101 guidance commands
Messerschmitt- Bolkow -Blohm GmbH Image display device Bruce Diamond Corporation 1306130
Directional wireless systems 1304276 Reproducing stylus Nippon Hoso Kyokai
1303657 Ricoh KK 1305111 Converting equipment of standard
Muirhead Ltd Magnetic recording and reproduction Western Electric Co Inc television broadcasting signals
Facsimile apparatus 1304288 Visual display apparatus 1306178
1303694 Farnell -Tandberg Ltd and Dakin A W 1305117 Standard Telephones & Cables Ltd
International Business Machines Production of sound tracks on cine- British Aircraft Corporation Ltd Television video signal processor
Corporation matographic film Antennae for transmitting and receiving 1306194
Magneto -optic transducing system and 1304363 radiation AKG Akustische U Kino -Gerate GmbH
method for reading superimposed EMI Ltd 1305148 Spring system
magnetic recordings Recording apparatus Sony Corporation 1306197
1303719 1304383 Magnetic erasing head Bell & Howell Co
Sony Corporation RCA Corporation 1305234 Motion picture projector with film
Magnetic recording and reproducing Amplitude control circuits International Standard Electric cartridge support assembly
apparatus 1304461 Corporation 1306366/7
1303720 RCA Corporation Convergence circuits Communications Patents Lyf
Standard Telephones & Cables Ltd Multiple channel display system 1305244 Wired broadcasting systems
Gain control circuits 1304492 Toho Machine Co Ltd 1306376
1303792 Philips Electronic & Associated Mounting of tone arms for record Thomson -CSF
Gabr, S Z M Industries Ltd playing units Bandwidth compandor system
Electro acoustic transducer Circuit for producing an aperiodic 1305303 32 10.
30
 B EyE FR L7`NAM C I

M 500 N
Unidirectional Studio Microphone Dynamic Unidirectional Ribbon Microphone
The M 69 is an unusually sensitive microphone A ribbon microphone designed for capturing the
with outstanding cardioid characteristics. It full intensity of modern music while suppressing
makes high -quality transcription possible even undesirable side effects such as popping, breath
under acoustically unfavourable conditions. The noise and hissing. Flat frequency response, high
well -balanced response curve of the microphone sensitivity and excellent front -to -back ratio are
maintains the highest fidelity in the reproduction the distinguishing features of this new BEYER-
of speech and music. Version SM with VOICE - DYNAMIC PRODUCT.
OFF -MUSIC switch.
Specifications:
Specifications: Frequency Response: 40-18000 Hz. Output Level at
1 kHz (0 dbm A 1 mW per 10 !Lbar) 0.13 mV/!Lbar
Frequency Response: 50 -16000 Hz. Output Level at
( -55 dbm). Polar Pattern: Hypercardioid. Output Impe-
kHz: (0 dbm _ mW per 10 ;Lbar) 0.24 mV / :Lbar
Load Impedance: > 10000.
1 1
dance: 50052 _: 15 "Í,.
( -50 dbm) Polar Pattern: Cardioid Output Impedance:
200 ohms. Connections: 3 -pin plug T 32621 3 200
Connectors: 3-pin Tuchel T 3262,1 - 3- 50012.2 ground

-3 -
M 500 N (T) Tuchel T 3007 spez.,1 2 - 5000, 3
ohms, 2 ground. Dimensions: 6.7" x 0.9 "0, head 1.7 "0
+

ground M 500 N (C) Cannon XLR 50 T, 2 3

Also available with Cannon connector XLR -3 -50T 50012,
1 ground. Dimensions: Head diameter 56 mm,
shaft diameter 28 mm, length 180 mm, weight 210 g.

M 160
Dynamic Moving Coil Microphone Dynamic Unidirectional Microphone for
With hypercardioid characteristics and unusually
Studio Purposes
high sensitivity. Due to its very good front to By using the double ribbon principle the highest
back ratio it is less subject to feedback and pro- possible reproduction quality of music and
vides excellent discrimination against unwanted speech is guaranteed. Non -linear distortions are
sound. It is used by broadcasting and TV-studios, imperceptible.
recording artists, bands and instrumentalists.

Specifications:
Specifications:

1
Frequency Response: 30 -20000 Hz. Output Level at
kHz: (0 dbm mW per 10 :Lbar) 0.25 mV rLbar
1
1 kHz: (0 dbm !
Frequency Response: 40 -18000 Hz. Output Level at
1 mW per 10 !Lbar) 0.1 mVJ!Lbar ( -57
dbm). Polar Pattern: Hypercardioid. Output Impedance
( -50 dbm). Polar Pattern: Hypercardioid. Output Impe- 200 ohms. Connections: 3-pin plug T 3262 1 - 3 200
dance: 200 ohms. Connections 3 -pin plug T3262 3
1 : ohms, 2 ground. Dimensions: 6" x 0.9`, head 1.5'0.
200 ohms, 2 ground. Dimensions: 6.5" x 0.9 ", head Also available with Cannon connector XLR- 3 -50T.
1.9"0.

Also available with Cannon plug XLR -30 -50 T (M 88

N (C))

Dynamic Unidirectional Ribbon Microphone To: BEYER DYNAMIC (G.B.) LTD.

The M 260 is especially suited for speech and
music reproduction. It has excellent transmis- 1CLAIR ROAD
sion qualities. The dampening effect backwards
is almost constant over the whole frequency HAYWARDS HEATH, SUSSEX
range.
Version SM with 3 position Voice -Off -Music
switch. Please send me full particulars and illustrated
brochure of BEYER DYNAMIC Products.
Specifications:
Frequency Response: 50 -18000 Hz. Output Level at
1 kHz: (0 dbm 1 mW per 10 :Lbar) 0.09 mV /ubar NAME
( -58 dbm). Polar Pattern: Hypercardioid. Output Impe-
dance 200 ohms. Connections: 3-pin plug T 32621 4 3 ADDRESS
200 ohms, 2 ground. Dimensions: 6.5" x 0.9', head
1.7 "0. Also available with Cannon connector XLR -3 50T

STUDIO MICROPHONES
STUDIO SOUND, APRIL 1973 31
 PATENTS January 10, 1973 January 17, 1973 1309400
1307480 1308056 Licentia Patent-Verwaltungs -GmbH
Philips Electronic & Associated Indus- Solartron Electronic Group Ltd Reproduction arrangement for repro-
tries Ltd Input circuits for electrical instruments ducing information stored on a disc in
Cassette for a magnetic recording disc 1308079 a spiral groove
January 4, 1973 1307531 Forster Elektronik GmbH
1306471 Bellis, T G Combination of a data processing or
Eastman Kodak Co Antifade devices for aerials writing head and an endless tape January 31. 1973
Motion picture projectors 1307560 magazine 1309489
1306584 Matsushita Electric Industrial Co Ltd 1308082 International Standard Electric Cor-
Vockenhuber, K and Hauser, R Apparatus for facsimile using prism - International Business Machines Cor- poration
System for reproducing motion pictures shaped fibre optics poration Snow and ice removal system for an
1306848 1307566 Method of making a magnetic head antenna
Sony Corporation International Standard Electric Cor- assembly 1309531
System for producing an electrical out- poration 1308158 Bio- Dynamics Inc
put signal in correspondence with a Decoder for the high colour fidelity Matsushita Electric Industrial Co Ltd Adaptor for use with an audio repro-
magnetic flux generating source reproduction of a PAL encoded colour Tape recorders and /or players ducing machine
1306898 signal 1308175 1309570
Porsche KG Dr -Ing HCF 1307587 RCA Corporation General Electric Co Ltd
Loudspeaker arrangement in a vehicle International Business Machines Cor- Television camera utilising a colour Degradation detection in a pcm system
1306912 poration encoding filter 1309632
PPG Industries Inc Multipletransducing element magnetic 1308192 Metro Goldwyn- Mayer-British Studios
Liquid crystal cells heads Matsushita Electric Industrial Co Ltd Ltd
1306999 1307608 Tape recorder Mechanisms for transporting cinema-
Pacific Plantronics Inc Matsushita Electric Industrial Co Ltd 1308629 tograph film
Headsets Multi -track dual gap magnetic head International Standard Electric Cor- 1309818
1307059 assembly poration Sued -Atals -Werke GmbH
Bosch Photokino GmbH, Robert 1307722 Method of determining the varying Magnetictape recorder having a friction
Device for simultaneously winding and Soc D'Applications Generales D'Elec- equipment delays for pulse trans- wheel drive for the spool carrier of the
unwinding an endless band tricite Et De Mecanique ponder tape
1307146 Magnetic recording apparatus 1308636 1309951
Staar, SA 1307725 Agence Nationale De Valorisation de International Business Machines Cor-
Apparatus for reading magnetic tapes Pasquali, G La Recherche poration
stored in cassettes Musical sound generating device Electrical filters enabling independent Time domain equaliser and method of
1307212 1307761 control of resonance frequency and of measuring distortions in a data trans-
RCA Corporation Ampex Corporation bandpass especially for a speech mission system
Waveform source for television Verifying the recording of information synthesiser 1310036
receiver on a magnetic recording medium 1308704 LTV Electrosystems Inc
1307269 1307777 Honeywell Ltd Signal synthesiser
Chicago Musical Instrument Co EG & G Inc Tape guide arrangements 1310165
Electronic musical instruments having Method and apparatus for producing 1308956 Elektroakusztikai Gyar
dc keying compressed digital representations of Matsushita Electric Industrial Co Ltd Sound radiator
1307270 a visible image Multi- element magnetic head 1310178
Chicago Musical Instrument Co 1307821/2 1308974 Nippon Columbia KK
Electronic musical instruments having RCA Corporation Instrument Systems Corporation Tape movement detecting devices for
a unified keying circuit Web cartridge Electronic voice annunciating device tape recorders

Higher -fi from telephones than the gripped regions. The parts of the straight regions 16 and 18 and the wrap angle
WITH THE current worldwide obsession for diaphragm which are separated by the second produces a separation between the tape and
broadcasting telephone calls, basically not a harmonic nodal line move in opposite directions surface 12 of about 2µm.
bad idea but in practice often excruciatingly and it is claimed that the resulting resonant But the tape does not follow the ideal path
boring, the proposals for a higher -fi telephone peaks are less pronounced; thus the final at 24. Where the wrap angle is about 10° or
transducer to be found in BP 1,293,670 from frequency response smoother and the sounds less, there is insufficient arc length between the
Siemens AG have some relevance to the present clearer. The patent specification is itself not points 26 and 28 to keep the tape stable and it
pages. the clearest of documents but presumably often rucks downstream. This rucking results
The operating frequency band for telephones Siemens get reasonable results in practice. One from non -symmetrical pressure distribution
is approximately 100 Hz to 35 kHz. According thought may cross cynical minds. The public between the tape and surface 12, a negative
to Siemens, most known telephone transducers at large are now so used to what a peaky
(i.e. microphones and speakers) have a drop in telephone sounds like that it may well reject an 34 *.
the upper limit of the transmission range. They improvement on the grounds that it sounds as
say this is usually fairly expensive to correct if there is something wrong with it. FIG. 1
but the frequency response can be flattened out
much more cheaply with their own proposals.

-
Briefly these involve mounting a metallic (e.g. Fluid bearings for tape
titanium) diaphragm which has a piezo -ceramic IN BP 1,293,205, IBM discuss the use of fluid
coating glued to it and connected to an ampli- bearings between tape and transducer heads.
fier and diode in the headset itself. The means The usual fluid is, of course, air and the obvious
of mounting is apparently the novel departure, advantage is reduced wear on the head and the
this taking the form of a ridged circle of silicone tape. But, nothing in this world being perfect,
rubber which grips the diaphragm round its all manner of problems arise -especially in FIG. 2
edge by two annular rings (fig. 1). By reason
of its inherent flexibility, the silicone rubber
maintaining the 1:1 ratio of transduced signal
characteristics for forward and backward tape
18 18
J_ 81

allows the diaphragm to vibrate with resonance drive.

peaks which correspond not only to the Fig. 2 shows a conventional fluid bearing A ' -R .
IB

fundamental of the diaphragm but also to other head. The head 22 has a gap 20 nominally at
harmonic frequencies. These have vibration the centre of a curved region 14 of a guide
nodal lines in parts of the diaphragm other surface 12. The curved region 14 merges into r 161E

rA1P-
32
 "Kee built -TO STAND ON ITS OWN
Series II CNS Unit MAINS POWERED
As follow up to our very successful
a

Cross -talk and Noise Suppression Module

The Series II Free Standing Unit offers all the
Functions of the Module Plus Continuously
Variable Suppression.

INPUT GAIN Continuously Variable Rotary Control.

SUPPRESSION Rotary Control Giving a Range of 4 to 18 dB.

SUPPRESSION IN 'OUT Miniature Toggle Switch.

SUPPRESSION INDICATOR Light Emitting Diode.
POWER 220/240V 50 60 Hz, via Cannon Mains Socket.
AUDIO TERMINATIONS Jack Sockets, Standard or Cannon Type to order.
PRICE £98.00 Un -bal. Delivery Ex- Stock.
£121.00 Bal.

/46.:Ce (STANCOIL LTD)., ALEXANDRA ROAD, WINDSOR, ENGLAND

Tel: Windsor 51056.

STUDIO SOUND, APRIL 1973 33

MI PATENTS Fluid coupling for tape drives arranged in groups of chromatically adjacent
NORMALAIR- GARRETT (Holdings) Limited in BP musical notes (e.g. F. F and G; G sharp A and
1,294,178 have had claims accepted for the A sharp etc).
pressure region arising because the bearing fairly basic principle of using fluid transmission When one of the keys of the left -hand part
fluid (air) cannot flow into the space beneath between tape deck motors and the take-up and of the keyboard is pressed, it will produce a
the tape quickly enough when the tape is take -off shafts which they drive. So apparently normal note by conventional means and will
moving at high speed. So the tape gets dragged the Patent Office Examiners regard the idea as also close a key switch which will apply a
down out of its true and ideal line of travel. new. voltage via lines 32 to the emitter of all the
What is more, unless the gap 20 is absolutely Fig. 5 shows take -off spool 10 and take -up control gates for the same basic material note
exactly half way between the points 26 and 28, spool 15 with tape 11 passing past heads 12, (fig. 6). Each of the control gates will so far
the tape performance will be different for and tape pinch drive 13, 14. All this is quite block this potential from its collector line 38
forward and backward directions of travel. conventional and driven by a motor 19 via to an associated keyer circuit 12 for a relevant
What IBM propose as a solution is to gear trains 16, 17. But the motor 19 also drives one of the series of tone producing means (fig.
provide slots (see figs. 3 and 4) at 44 and 46 a gear train 20, 21 to rotate the outer half of a 7). This blocking effect can be removed for
upstream and downstream of the gap 20. These rotary vane fluid damper 22. This is a conven- any control gate by making its base more
tional fluid transmission with viscous fluid such negative than the applied potential on its
as oil, the internal half of the drive being emitter. And obviously the gate will conduct
FIG. 3 directly coupled to the take -up spool 1.5. Thus in the manner of a pulse if the voltage applied
the take-up drive is from the motor 19 but via to the base is in the form of a pulse. These
a viscous fluid coupling. pulses are produced by the cascade circuit 24
In another design, both the feed and take -up mentioned above and fed along the lines 28 to
spools are driven via fluid dampers of this the chromatically associated groups of control
general type. The theory is that the tape can gates 29. So a first pulse passes to the gates 29
never be over tensioned and there seems no associated with the notes F to G; a second
reason why this should not work well. But pulse comes along the next line 28 to the gates
surely it has already been tried? associated with the notes G sharp A and Asharp
and so on with the sequence continuing so that
each of the chromatically associated groups of
control gates is successively triggered with time
Automatic arpeggios spaced pulses. It follows that, depending upon
BP 1,295,994 from the Chicago Musical what keys are depressed on the left -hand
Instrument Company takes a great deal of portion of the keyboard (i.e. what chord is
wading through and for me the going was even being played there), the corresponding tone
FIG. 4 tougher because I fear the end product in terms producing means will momentarily be ener-
of sounds produced by the invention will be gised in sequence to provide an automatic
pretty nasty. But duty dictates that I report it. arpeggio. Adrian Hope
,r The patented gadget will make it possible for
Ad

:i-n' musicians to incorporate musical flourishes

FIG. 5
,e--
into their playing despite the fact that they lack
the technique to do it for themselves.
The instrument may be an organ or electronic
`piano' with a conventional keyboard having a
left-hand portion and a right -hand portion. A
slots communicate with atmosphere at their series of tone producing circuits are keyed by
sides and so prevent the possibility of any the right -hand keyboard in the usual way but
negative or positive pressure discrepancies the organ also has an arpeggio switchrwhich
arising at either side of the gap 20. Doubtless can feed voltage to a triggerable circuit. The
the exact dimensions of the slots will require circuit has an output coupled to an amplifier,
very careful calculation or a great deal of trial itself coupled to the input of a cascade circuit.
and error experimentation. Will slots which The arpeggio switch also feeds a reset circuit.
work for one type of tape work properly for The cascade circuit has a series of separate
another? stages which progressively respond to a
potential increase applied from the circuit
input, each stage being connected to a series
FIG. 6 of signal control gates. These control gates are FIG. 7

n uro vecrn)

tavo

1G

IJ.

A s
r

1A
1A

3L

34
 A PROGRAM LEVEL meter is part of the by the operator. Due to the a/d conversion at
monitoring hierarchy around the sound con- the input, logical operations like this can easily
sole. It may be classified as an output device be obtained at negligible extra cost.
which gives a visual indication of the sound Digital logic circuitry has become the most
level. For audio systems in direct connection widely used means of solving data handling
with radio transmitters and /or tape recorders, and sequencial control problems. While circuit
it is extremely important to know the peak level costs fall, the variety of available functions
in order to avoid over-modulation. grows. The digital code can be fed to remote
The conventional moving -coil movement or equipment, should a future need for this arise.
light-spot galvanometer can be replaced by a Program can be routed in coded form to the
string of light emitting diodes (leds). Red producer, co- engineer, or to wherever this
diffused-lens leds give better readability, less information is needed. Conversely, digital
susceptibility to washout from high ambient information from several ppms can be multi-
light, and are resistant to mechanical shock. plexed and transmitted bit- serially on a single
And, on the human engineering side, the line.
column of light leads to a faster and easier The monitor display unit mentioned earlier
reading without eye-strain. Such a display of displays a column of light but the transmitted
instruments may also be equipped with termin- information might equally well be decode'd to
als for dimming the display, which leads to obtain numeric readout of the program level,
comfortable viewing independent of ambient then displayed on seven segment readouts.
light conditions. The design is kept simple and clean but
Analogue to digital conversion eliminates the complex solutions may be realised, to individual
need for logarithmic amplifiers and provides a need.
high degree of stability and accuracy. Digital
logic circuitry has proved its reliability in
computer circuits during the last decade and is
gaining increasing attention in sound control.
Each ppm consists of three basic parts: an
analogue to digital converter, a display, and a
memory.
The a/d converter receives the analogue volt-
age (i.e. the sound program level) at the input +6
of the instrument and converts it to a digital
code proportional to the input level. The
logarithmic characteristic timing network that
determines the integration and fallback is
included in the a/d unit. These parameters can TEST-
easily be varied within wide limits to satisfy
different requirements, simply by changing

Opto- component values in RC- networks. Fallback

time can even be altered from outside to suit
different situations.

electronic Resolution
The resolution of the ppm is given by the
number of bits in the digital code. If the
12
audio instrument is to cover a range of 50 dB, which
is good enough for most applications, a six bit
code is required to give 1 dB resolution all over
the scale range. A six bit code can give 28 =64

level different binary combinations while a five bit

code can only give 26 =32 combinations, which
is not sufficient to display the level in I dB steps
18

display over a 50 dB measuring range. However, a five

bit code can be used if the operator is content
with 2 dB resolution.
The ppm display unit receives the digital
code from the a/d converter, decodes it and
2
RUNE ESPELIEN* displays it as a column of light (not, it should
be emphasised, as a moving spot).
dB
Incremental light- emitting diode
meters offer much more than an
The height of the light column corresponds
to the input level, and a thermometer type of 30
alternative to moving -coil units. In instrument like this is much more comfortable
to read than the wildly twitching pointers and
addition to being resistant to
physical shock, digital displays can
moving spots of conventional ppms. Even with max
a peripheral view, the operator can easily read
be designed to store the maximum the length of the light column. This is import-
level reached during an
unmonitored program sequence.
ant as the operator is usually busy with a vast
number of processing controls.
!36
Perhaps more promising, remote
devices may be triggered at any The memory
set
preselected program threshold. This, the third unit of the system, consists
of a few arithmetical elements which operate
on a pure digital basis. The maximum peak
*Digital Design, Box 1220, 7001 Trondheim. Norway value can be stored until the memory is cleared
STUDIO SOUND, APRIL 1973 35
 DIARY By John Dwyer

THE NEWS that Bonochord had made an Party. continued through the first half of 1972. The
offer for Neve was released towards the end of Three years later Bonochord contracted a chairman was careful to point out, however,
December last year. Neve's press statement bad case of diversification to the head and that the losses had been `stemmed' and `with
said that they had accepted the offer and that bought, would you believe, a group of printing the introduction of new management it is
'the direction and Management of Rupert Neve firms. They kept them, I need hardly say, for a considered that a return to profitability would
and Co would remain unchanged'. matter of months. be received on a modest scale in the last quarter
Briefly the terms of the takeover were as In 1969 Mr Robin Rigby became chairman of this year.'
follows: Bonochord would first acquire 51 per and began a ruthless but necessary campaign to Concerning APT, in the same annual report
cent of Neve's shares with a payment of weed out the unprofitable parts of the company, the chairman said that it would take too much
£170,000 plus £4 for every £1 that Neve's profits rationalise (and we all know what that means) valuable cash to put APT's power supply
went over £100,000 for the 25 month period up the rest and buy up other, more profitable, business right. The power supplies, which had
to the end of 1973. This payment would be enterprises. once been about 80 per cent of APT's business,
limited to £89,760. In March 1970 Bonochord bought a firm had now dwindled to about ten per cent.
The second part of the deal concerned buying called Terminal Insulators Ltd for £115,000. Accordingly Bonochord sold the power supply
the remaining 49 per cent of the shares. TI made electrical and electronic components division of APT to Unitech Ltd for 'between
Bonochord would pay £5 for every £1 of the and plastic mouldings and the Investors £200,000 and £250,000'. The remainder of APT
average profits of Neve over three successive Chronicle of September 4, 1970 said that the has now become the radar division of
years. It would be up to the Neve shareholders new company would enable Bonochord to Bonochord and seems to be successful; at the
whether that three year period would end on reach new profit levels. In October of the same beginning of February they announced they
December 31 of 1975, 76 or 77, but if they year, Bonochord took over Hammant & had won another contract for three automatic
had not decided by 1977 then Bonochord could Morgan, makers of light electrical control tracking radars worth £100,000.
acquire the remaining shares after 1977. equipment for the toy industry. Nevertheless, if you read what Mr Rigby had
Neve's fortunes have improved greatly over In December Bonochord merged with APT to say about some of Bonochord's subsidiaries
the last couple of years. Up to the end of Electronic Industries, makers of power supplies, you realise how lucky Bonochord were to have
November 1971 their profits were only £4,000 language laboratories and radar equipment. bought Viennatone: Hammant and Morgan
but thirteen months later Neve were predicting APT were important to Bonochord because were 'a little disappointing'; Path Engineering,
that their pre-tax profits for 1972 would be they had collared a number of Government a firm of precision engineers, were 'still by no
£20,000 and that in 1973 they would make contracts for radar equipment. But, although means buoyant'; Shepherd Finance Ltd
£80,000 on sales of about £1,250,000. At the APT had made £93,000 in 1970, compared with continued to show improved results' and
time of the takeover Neve had outstanding £71,000 in 1969, the Investors Chronicle Jennings Electronics Industries 'had their loss
orders worth about £600,000 and assets of remarked gloomily: 'APT faces poor demand reduced' ... somehow, and it is to their credit,
around £250,000. for electronic equipment and keen competition Bonochord just aren't in the Slater Walker
I asked Mr Metcalf Collier, secretary of for language laboratories'. class.
Neve, why the firm's profits had risen so During September of 1971 Bonochord Some other recent Bonochord takeovers are
sharply. He explained that there had been a bought Aveley Laboratories, who had exhibited worthy of attention. The first of these are the
number of production difficulties in the past at Internavex a 'new, improved and more acquisitions of H & E White and Fairlawn
which had now been sorted out. I also asked comprehensive range of language laboratories Finance, whom Bonochord amalgamated to
him if the figures hadn't been made to look a of advanced design'. The £118,420 deal form what they called 'a flourishing unit'. The
little better than perhaps they were, to which he included a firm of opticians called Boume next offer to buy was sent to Livingston Hire,
replied that this was certainly not the case. Optical -an area that Bonochord were to the studio equipment and measuring instrument
The history of Neve's new owner has hardly develop later on when they bought Thompsons, hire firm, to whom they offered £1,400,000. At
been that of one success after another. Although a Cardiff opticians' firm, in December of last the time of the takeover, Livingston, who
Bonochord made £204,000 in the six months to year. operate both here and in West Germany, were
the end of June, 1972 -an increase of £79,000 But the most important buy of 1971 was the forecasting profits of £167,000 for the year to
on the corresponding period of 1971 -as little acquisition of the Austrian firm of Viennatone, April 30, 1973. Cannon Street Investments,
ago as 1969 Bonochord were in what one with its subsidiaries, for £348,000. Viennatone who held just over 50 per cent of the Livingston
financial journalist described as 'a truly made, sold and exported hearing aids and were shares, agreed to accept the offer.
bombed -out state'. very successful; ever since Bonochord took Livingston were the first Bonochord buy in
The firm had been founded as Allen & them over, in fact, Viennatone seem to have what they obviously intended would be a
Hanbury's (Acoustic Aids) Ltd in May 1939. been propping up Bonochord's less able series of moves into the audio equipment
The market for their products, hearing aids, subsidiaries. market. In July the Financial Times predicted
was big enough but they had reckoned without Terminal Insulators did not run as planned. that various factors 'could lead to further
the Government's making someone else's In the annual report for 1971 the chairman, acquisitions before long' and of course they
hearing aid free on the National Health. The Robin Rigby, was obliged to make the rather were right.
public, it seemed, needed a hearing aid you had embarrassing announcement that the forecast The reasons why Neve were so attractive
to pay for like the Czechoslovaks needed had been exceeded in spite of the large loss were that, first of all, they had good sales and
Adolf Hitler. made by Terminal Insulators. He went on: profit figures; secondly, that Bonochord needed
In 1949 the name of the firm was changed to 'Because of accounting errors, which led to to complement the range of studio equipment
Bonochord and the company went public ten erroneous information being supplied, your that their Aveley subsidiary are about to
years later. In the decade after that the only board was not aware of the high level of this market; and thirdly that Neve had had long
bright spot in Bonochord's fortunes, if you can loss when the interim results for the half year experience of both studio equipment and its
call it a bright spot, was the knighthood of ended June 30, 1971 were announced on market. For their part, Neve were willing to
their chairman, Theodore Constantine, in the October 7, 1971.' succumb to Bonochord mainly because
1964 New Year Honours list; he had worked as Terminal Insulators had lost more than Bonochord had an established and successful
a constituency chairman for the Conservative £100,000 during 1971 and the losses had 38
36
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 DIARY leading Canadian broadcasting company; and Malcolm Davies has now taken over as
John E. Dallas Ltd. Shareholders not on the studio manager of Apple. I wish him even
board include Colin Kelsey, Norman Strauss more luck than Geoff Emerick.
and John Maddox. Sound Developments. Sessions on Horlicks
European sales organisation- something Neve When the names were announced, Michael commercials for J Walter Thompson and
wanted badly. Levete said that he thought the news station Carling Black Label for McCann Erickson;
There is one other interesting facet to the would cost about £1,000,000 to set up and Sound Developments also did WEA Records'
takeover. As is well known, Neve are asso- would lose money during the first two years. presentation for the Midem festival at Cannes.
ciated with Christian missionary work, though Listeners would be ten minutes from a news Other sessions have included Party Pops album
nobody is quite sure how. By a coincidence, bulletin during peak listening times and never of instrumental hits, produced by Bruce Baxter
Mr D. C. Rennie, CEng, FIEE, joint managing more than 20 minutes from one at any other for Pickwick; Ernie Entwhistle and Carl
director of Bonochord, is also a director of time. Simmons, whom Adrian Sear describes as a
Billy Graham Evangelistic Alliance Ltd. It is believed that the cost to LBC of renting `Jerry Lee Lewis type rock and roller', were
The IBA have announced, rather before the transmitter from the IBA will be £180,000 both produced by Hal Carter's company Dash
anyone thought they would, the names of the in the first year rising to £230,000 in the third productions. All the above were engineered by
two London commercial radio contractors; in and final year of the contract. The correspond- Adrian, as were some sound effects for Peter
January the IBA had said the names of the ing figures for the General station could be as Sinfield, producer for Roxy Music now doing
lucky winners would be announced at the end high as £315,000 and £380,000. his own album at Command.
of March, but the announcement came at the Next the IBA will allocate the contract for Impulse. This studio, way up on Tyneside,
beginning of February. the Birmingham station to one of the four
The General station has been won by went four track about two years ago and they
groups who have applied. By far the biggest of tell me that since they added a four track
Capital Radio, a consortium chaired by these four are Birmingham Broadcasting. The
Richard Attenborough and comprising Bryan Ampex to the set -up studio time has more than
IBA have made it quite clear that you won't doubled. Because of this they were able to
Forbes; Michael Flint, the former head of get any contract if you don't have any loot.
Paramount Pictures UK; David Jacobs; Air Birmingham Broadcasting have not only the start alterations for a second, eight track
studios' George Martin; Alan Bartlett (of loot but the backing of some of Birmingham's studio in September of last year. The new suite
will be ready by about April 23, after which the
Bristol Industrial Securities); Robert Stiby; most prestigious citizens-not that that will original studio will be converted into a dj
William Beets, Graham Binns; Ronald Denny; have any bearing on the prestige or otherwise
John Littlejohns; and the man who started the studio, ready by May or June. Impulse started
of the programs they would produce. about six years ago and played, I am told, a
company, Weybridge dentist Barclay Barclay- Marquee. The studio reopened at the
White. Apart from individuals, the group also large part in the success of the Lindisfarne folk
beginning of January after closing to have a group. They still retain a heavy interest in the
includes Rediffusion, the Observer newspaper new MCI 24 track desk installed. Marquee say
and Local News of London, a newspaper group's publishing business. Recent Impulse
it is the first 24 track in the country. The
consortium comprising 22 local newspaper releases include a Derek Brimstone album for
acoustics in the control room were designed by Rubber Records, and an 1p called Geordierama,
groups. Ken Shearer.
The consortium which will run the News
for MWM Records. They also did incidental
Dave Kent -Watson of Indigo tells me that music for Tyneside Theatre Productions' Peer
station is London Broadcasting, headed by they have been very heavily booked lately and
Sir Charles Trinder, a former Lord Mayor of Gynt, which was played by part of the Northern
have had some enquiries for eight track recor- Sinfonia. At the moment they are busy record-
London. This is the consortium to which IBC ding. As a result, they have now bought an
studios belong. ing an 1p by Hedgehog Pie.
George Clouston, IBC's eight track Ampex MM//00 machine which
manager, will be on the board in charge of Dave tells me were delivered in late February. Roger Squire. A film unit making a docu-
production. Another member of the consortium 'Rates for eight track recording will be very mentary about Radio One for Anglo EMI have
is Sir Gordon Newton, former editor of the competitive at £16 an hour,' he said. 'Reduc- spent a whole day at Squire. The result of
Financial Times and newly appointed chairman tion to stereo will be £12 an hour.' Indigo's their visit will be used to show the kind of set-
of Vavasseur, the firm that have made a take- other rates are £12 for four track, £8 for two up a dj uses to prerecord his material.
over bid for John Bentley's Barclay Securities. track and £6 an hour for mono. Advision. Gary Martin engineered an album
Sir Gordon will be chairman of the editorial Other big news from Indigo is that they have for Stomu Yamash'ta. Stomu is regarded as
committee. signed a publishing deal with De Wolfe one of the world's leading percussionists and
The other members of the board are Michael Publications in London. writes for, produces for, and directs his own
Levete, who will be managing director, Air. As just about everybody knows, Roxy theatre-the Red Buddha. He opened at the
Canadian broadcaster Kenneth Baker (market- Music have visited AIR to produce and record Roundhouse on January 29 and finished on
ing), Roland Freeman (local government), a new album; Rick Wolf was produced by March 3.
Alfred Geiringer (wire services), Adrian Ball Roger Cook; Fleetwood Mac did mixing and More recently, Darien Spirit have been
(networking), Mollie Lee (women's affairs), overdubbing; John Williams produced by recording their first as yet un -named album
Brenda Maddox (Education), and Michael George Martin, as was the Huggett Family; under the production of Steve Rowlands. The
Rapinet (company secretary). Casuals, Shoot, Gary Moore Band, Mott the group are Scottish and include two former
The London Broadcasting Company was Hoople, Wishbone Ash, Terry Stamp all did members of the Bonzo Dog Band. Martin
started by Roland Freeman, once a chairman sessions; Brenda Arnau mixed some tracks; Rushent engineered the album, which will be
of the GLC's finance committee and now head Kings Singers did a mobile in Church; provi- released on Charisma. Steve and Martin also
of a firm of public relations consultants. He sional bookings include ELO and Roy Wood's co- operated on a Philips album and single by
met Michael Levete, an executive of the Wizzard and demos are being recorded for the Rosetta High Tower, ex lead singer with the
Charterhouse banking group, while engaged on new James Bond film 'Live and Let Die', for Orlons. The single will be One More Heartache
a London building project. By the time LBC which George Martin has composed the with the Bee Gees number The Walls Fell Down
makes its first broadcast Mr Levete will have music. on the flip side.
resigned as chief marketing executive of On the staff side, Geoff Emerick, who left Finally, I went to a press do given by Zoom
Charterhouse, who have a large shareholding Apple at the beginning of February, has joined Television not long ago and I will be reporting
in LBC. AIR after taking a short holiday. For those on them next month. Also in next month's
One member of the LBC board has already who haven't heard of Geoff Emerick-and it `Diary' will be a report on SB Independent
resigned: Norris McWhirter, brother of Ross seems there are one or two within mic range of Radio. I've had a number of complaints that I
'Oh- What -A- Lovely -Warhol' McWhirter. I the APRS -he engineered Sergeant Pepper and tend to cover the same old studios month after
understand that Norris resigned just after the his work on it won the first Grammy for a month. I accept this criticism but if `Diary' is
Warhol fiasco `to avoid embarrassment to the British pop ]p. Later, he and Phil McDonald to be compiled within the time allotted there
company. There was no pressure from us of Apple won a Grammy each for Abbey Road, are only so many new studios I can visit; others
w hatever'. an album which EMI say has sold more copies send me the information regularly and if I can I
Other members of the LBC consortium are than any other Beatles album -at the last repay this courtesy by giving them some space.
Universal News Services, Selkirk Holdings, a count the score was 7,600,000 copies worldwide. So it's up to you.
38
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Durante il recente incontro del corpo dirigente, é stato
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STUDIO SOUND, APRIL 1973 39

 VIDEO By Roderick Snell

MULLARD XQ1402 FIG.1 TYPICAL

CENTIMONY- TRISOLPHIDE VIDICON
F G.
I 2 MULLARD XQ1400 SPECTRAL RESPONSE
LOW LIGHT TUBE 100 103 102

° BO

REGULAR VIEWERS of `Tomorrow's World `,1' 60

°
will be aware that cameras (sophisticated of
course) can now be made so sensitive that one
: 102 10

a Lo
can televise scenes too dark for the eye. Readers
of the technical press might in turn believe that
flat solid -state image sensors the size and
thickness of a postage stamp are just round the
i 20

corner. Still the majority of closed-circuit

television pictures remain at best obviously 0
Loo 600 600 1000 1200 10 L00 600 600
1

1000 1200
`non -broadcast' and at worst scarcely viewable. WAVELENGTH Inm1 WAVELENGTH /1m)
Whether it is simple monitoring for security in
a shop, safety in a London Underground
station, or seeback in a recording studio, the
most common problem seems to be lack of
light. Most cctv users accept this as an unavoid- FIG. 3
able weakness of the camera and, if they have
the money, invest in high power lighting grids,
portable `spots', and so on.
Aside from increasing the light level (or
making better use of available light), there are
at least three other worthwhile approaches:
increasing the lens diameter, improving the
camera, and improving the pickup tube.
A wide aperture lens certainly accepts more
light but one is then left with an uncomfortably
shallow field of focus. Decreasing the focal
length (i.e. increasing the acceptance angle) is
often worthwhile; the 25 mm focal length of the
normal fixed lens can be reduced by a factor of
two and costs between £40 and £100. This wide
angle is suitable for many applications and
gives two stops improvement in sensitivity for
the same depth of focus.
There are quite large differences between
cameras of the same price range. Once bought,
there is usually little one can do other than
make sure the vidicon beam and target adjust-
ments are optimised for the light level being
used. But, given an initial choice, testing
prospective purchases at low light levels is
worth the trouble. Testing two British-made
cameras recently, the cheaper of the two had
more than one stop of usable pictures at low
light levels. Both cameras used the same
separate mesh 25 mm vidicon tube but it was
significant that the more sensitive of the two
used a field effect transistor in the head amplifier
and worked the tube in the `high field' mode, layer of the normal vidicon target. Bells' manufacturers are direct mechanical replace-
which is to say the maximum allowable mesh Picturephone requirements were long life, high ments for antimony trisulphide vidicons and
voltage was applied to the tube. This costs sensitivity and extreme ruggedness. Any tube will work in many cctv cameras with a few
more to engineer because higher powers are that could be damaged by direct sunlight or electrical changes. Industrial grades of tube
then needed to drive the scan coils. focused spotlamps, like the normal vidicon, cost upwards of £170 which, although roughly
If none of the above has given the required would not do but the resolution and blemishes six times the cost of equivalent antimony
sensitivity, one of the new generation of silicon could be worse than those in normal cctv. The vidicons, may save so many lighting and lens
target camera tubes is worth considering. last three years have seen much work in this problems that they become the easiest and most
First developed by Bell Telephone Laboratories field and silicon target tubes are currently economical way of doing the job.
for their Picturephone project, these tubes use a available in the UK from English Electric, The Mullard XQ1402 was chosen for the
mosaic of over 500,000 silicon diodes in place Mullard, Thompson CSF, RCA and Texas review because, unlike some other silicon
of the semiconducting antimony trisulphide Instruments. The 25 mm tubes from these 42
40
 --- 1 1

II
i
I
To Dixons Technical Ltd.,
3
:
41INwit,
Soho Square, London, W.1.
Please send me full details of your range
`
I of audio -visual equipment by return of post
Name
Address

Dixons
Technical
io SQUARE
f
Ltd 40.?

Cm" --
SHORT CUT
TO SOHO SQUARE.
At Dixons Technical we have the widest You'll find that we have all the famous
range of audio -visual equipment available in brand names; and they're yours at the most
Britain. And the expertise to match. competitive prices imaginable.
Which is great if you happen to be near Should you not wish to touch much needed
Soho Square. capital, we'll arrange a hire purchase agreement
But if you live out of town, why should you to suit your pocket. You can lease, or if you only
have to travel perhaps hundreds of miles, just to require a piece of equipment for a short while -
see us ? we'll rent it to you.
Well, quite simply, you don't! And wherever you are in Britain, the Dixons
At Dixons Technical well see to it that Technical after -sales service is ready to carry
wherever you live, the equipment you require out any necessary servicing or repairs with
reaches you quickly and safely. We'll give you speed and efficiency.
all the expert advice and So take the short cut to Dixons Technical,
assistance you may require. We're just a snip away.
We'll even make arrangements
for it to be
installed.
IN VIDEO

target tubes, it was capable of working at the

high voltages used in the Link 101 camera
without damage through self-induced X -rays.
Although not the cheapest, it also had better
resolution than some of its competitors and the
prospect of a long working life.
Two Link 101 cameras were set up, one with
a conventional separate mesh vidicon, the other
with an Industrial grade XQ1400. The high
impedance target bias was immobilised so that
the automatic sensitivity facility was lost; like
the lead -oxide photoconductive tube, this form
of AGC cannot be used on a silicon target type.
Making minor adjustments to match Mullards'
specified working voltages exactly gave no
improvement over Link Electronics' factory
settings for normal tubes so the original settings
were left. The silicon tube's resolution was at
first slightly worse, but the pictures were so
exceptionally noise -free that increasing the hf
response until the resolution was as good still
gave the most grain -free pictures we have seen
from this camera. Although only about five
times more sensitive to green light, in our
tungsten -lit laboratory the silicon tube appeared
over 50 times more sensitive: the reason for
this can be deduced from the spectral response
curves of figs. 1 and 2. The vidicon is panchro- adjustment was sufficient wherever the changes FIG. 4
matic, with its sensitivity, of about 100 nA /uW in illumination were not too great.
centred at a wavelength of about 550 nm,
which matches the response of the human eye.
On the other hand, the silicon tubes response, Conclusions
Where a few stops more sensitivity are sifiers which amplify an 'electronic image' of
with its greater sensitivity to infra-red, more needed, particularly in tungsten light, silicon the scene, giving an increase in optical sensi-
nearly matches the spectrum of incandescent diode tubes are worth investigating. They can tivity of between 50 and 100,000 times.
lamps and it is with these that the gain is so usually be fitted to existing cameras with very Although mechanically compatible as far as
worthwhile. This spectral response can some- little modification and, providing the light scan and focus coils are concerned, the intensi-
times produce peculiar visual effects, especially level changes are not too wide, are satisfactory fier section itself increases the length of the tube
outdoors in sunlight when the relative bright- with the lens iris adjustment of sensitivity. The so either a mechanical change or a new camera
ness of different objects is altered by their higher initial cost of the tube is partially offset is required. An additional eht supply of
infra -red reflectivity. Even indoors, a man by its long life expectancy and immunity from several kilo volts is also needed, which is
wearing a dark red shirt and blue tie may appear damage by over illumination. The Mullard available in the form of a potted transistor
from the screen to have a light grey shirt and XQ1400 tested here would not take long to fit invertor of only a few cubic centimetres volume.
black tie! However, indoor shots at light to most cctv cameras and gives comparable But this supply gives a convenient form of
levels considered comfortable for office or a resolution to a normal separate mesh vidicon gain control, lacking in the straight silicon
sound studio give very good noise free and tube but with greatly increased sensitivity and diode tube. Intensifier tube cameras cost more
lag -free pictures if lit with tungsten lamps. and should be given careful consideration so a
reduced lag.
Also the unity gamma characteristic gives an Where greater sensitivity is required, both list of manufacturers together with some
appearance of high -key lighting which is most types of tube are available with image inten- further reading is given below.
effective for monochrome work.
The two Link cameras were pointed at the
'scene' of figs. 3 and 4, which was lit with a
normal 40W bulb in an Anglepoise lamp. Manufacturers of low light television cameras
Directing the lamp away from the scene
reduced the light level until the normal vidicon
picture could no longer be considered usable Pye Business Communications.
(fig. 3). The light level was below the reliable Link Electronics.
range of our meter, but was in the region of J. D. Jackson Electronics.
1 Lm /m2. At this level, the silicon target tube Studio 99 Video.
was overloading so the lens aperture was
reduced by four stops (ie 1/16 of the light) to
give fig. 4. To give an idea of the difference in
lag between the two tubes, the white square Further reading
visible above the glass egg was attached to a
English Electric Valve Co: 'Silicon diode tubes' and 'Low
steel piano wire spring and made to bob up and
light television tubes' (reprints).
down. As most cctv cameras (including the
101 Links used in our tests) get their auto - J. D. Jackson Electronics: 'Low light television' (reprints
sensitivity feature by biasing the target through from US journals).
a resistor of 1000M /ohms or more, this system
cannot be used with silicon tube so an iris
Studio 99 Video: 'Development and use of a silicon target
control, neutral density filters, or some video
agc system must be used. We found that two tube and camera' (factsheet no. 2).
neutral density filters plus the normal lens iris
42
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BY AUDIO CERTRON & OTHERS and complete insert and assembly editing ; the IVC -900 Series 1"
5 SCREW TYPE INDEX CARDS AND CASES. helical scan recorders match broadcast standards. Soon to be
C60 25p, 10 for £2.35; C90 35p, 10 for £3.25; C120 45p, 10 for introduced is the IVC 100 series video cassette recorder which
£4.25. P/P 20p combines full IVC interchangeability and professional quality
INDEX CARDS 3p PER DOZEN with the convenience of cassette tape packaging. And there is a
comprehensive range of IVC cameras and ancillary equipment.
To ensure a professional standard of service to match their

RECORDING TAPES equipment, it is IVC policy to supply only through the following
accredited regional dealers :

SUPERB QUALITY WITH J C. W. Cameron Limited T. Moland Limited

LEADERS & BOXED POLY- Giffnock, Glasgow. Plymouth.
ESTER PVC & MYLAR BASED. E.O.S. Industrial Electronics Murray Swanson & Co. Ltd.
MANUFACTURED BY LEADING Llantrisant, Glamorgan. Newcastle- upon -Tyne.
ELECTRONICS FIRMS Hudson & Carter Limited Holliday Brothers
Chilwell, Notts. Cheshire.
Why not try one and cut your recording costs? Bell and Howell A -V Ltd., Wembley
Standard Play Long Play Double Play
5"
5r
600'
900'
35p
900'
40p
1200'
42p
55p
1200'
1800'
60p
80p ACTION VIDEO LTD
T 1200' 48p
1800' 70p 2400' 98p
45 Great Marlborough St.,London W.1.
EMPTY SPOOLS 5" 10p, 51 11p, 7" 12p. P/P 20p.
Telephone:01.734 7465/6/7
WALKERS ( S ) 16 Woodthorpe Road, Ashford, Mdx. 52136 PRODUCTIONS SALES SERVICE HIRE

STUDIO SOUND, APRIL 1973 43

 FROM MARCH 13 through 15, the Blooms- microphones, headphones and accessories, the
bury Centre Hotel will be graced with the M201 dynamic microphone, ST230 floor stand
presence of Sound '73 -an exhibition of sound and MTF 222181 microphone base plate. The
reinforcement equipment organised by the M201 is a hypercardioid microphone designed
Association of Public Address Engineers. The to look into lk ohms and measuring 155 mm by
hotel is situated in Coram Street, Russell 24 mm diameter. ST230 is defined as an
Square, London WC1 and exhibition opening `extremely portable' low price lightweight
times are 10.00 to 18.00 closing one hour early floor stand with provision for mounting two
on the final day. Tickets are available free of microphone holders without an additional
charge from the APAE Secretariat, 6 Conduit clamp. Beyer Electronics are Southern and
Street, London W1R 9TG (phone: 493 5256). Scottish distributors for Calrec Audio and will
A program of lectures and demonstrations also display the Calrec range of capacitor
has been prepared starting on Tuesday March microphones and audio mixers.
13 at 14.30 with a talk on `Microphones'. This Following confusion with the Japanese
is followed at the same time Wednesday by `Crown', their American namesake have
`Compressors and limiters' while `Industrial adopted a new label: Amcron. McInnes
design of public address equipment' commences Laboratories will display the full range of
at 10.30 Thursday. Amcron power amplifiers on stand 38. The
A new preamplifier for the C451 fet capacitor DC300 is being replaced by a DC300A operat-
microphone will be seen on the AKG stand. A ing into loads down to 1 ohm. Up to 500W rms
three -position switch gives flat response, 75 Hz per channel is the specified output power;
bass roll-off, or 150 Hz bass roll-off, allowing distortion is described as greatly reduced.
the microphone to be optimised for boom or Recently appointed agents for Dbx, Macinnes
hand -held operation. Model C414 is a new will exhibit examples of their noise reduction
capacitor capsule incorporating a pattern units including the 117 which is considered to
selector for cardioid, omni, figure-of-eight or have background music applications. It cuts
hypercardioid pickup. While this is intended out the music?
Sound '73: for recording studios, the D1200 and new D2000
are described as ideal for speech reinforcement.
The D2000 is directional and incorporates a
Mains and battery powered mixers and
amplifiers are to be exhibited by CTH Electron-
ics. Introduced last year, the MA30 amplifier

ó pé197
combined pattern selector and on/off switch. will again be displayed together with a range of
Made in Britain for AKG, the LM300 micro- transformers, cable drums and other public
the1973 phone is designed for low budget discotheque
systems.
address accessories.
Eagle are adding a sound level meter to
Association Exhibits on the Audix stand will include
modular power amplifiers (rated at 15, 30, 60,
their wide range of audio products -the Pro
TIM. This covers 36 to 130 dBA in seven steps.

of Public 120 and 200W rms continuous), limiters,

equalisers, noise sensors and loudspeakers.
The Pro A35, A65, and A120 amplifier series
will be on display and are claimed to be a new

Address These can be supplied to meet the needs of

recording, broadcasting or theatre studios. A
standard Audix audio control console is
concept in public address equipment. Features
include slider controls with preset markers,
priority page relay and resettable safety
Engineers illustrated below. Equipment similar to that
recently supplied for ITN outside broadcast
circuits. Respective output powers are 35, 65
and 120W rms. New Eagle electret micro-

Exnibition vehicles will be shown.

Among new additions to the Beyer range of
phones will include the Pro M5 tie-clip and
Pro M25 boom arm.
Recently developed Electro -Voice electret
microphones will be seen on the Gulton stand
together with a wide selection of loudspeakers.
The latter will comprise the SP12, SPI2B,
12TRXB and 12TRX, 30W, Musicaster 1A and
Eliminator 1.
Several newly developed items from G. H.
Garland. GM3200 is a battery /mains amplifier
module with automatic switching from mains
to a 24V dc auxiliary supply in the event of
power failure. The unit is also suitable for
powering mains equipment in the field and is
available with (optional) internal trickle
charging. GM22, a portable mono or stereo
discotheque system, incorporates two Garrard
SP25 Mkt turntables, bass, treble and gain
controls, microphone and a headphone
monitor amplifier. It is designed to feed two
free standing 100W amplifier modules and
comes complete with matching 100W loud-
speaker units. Matching horn units are also
available to improve the hf response. Other
items to be exhibited by Garland include a
range of remote gain controls and a family of
loudspeaker units for 100V sound distribution
systems.
A new series of public address amplifiers in
the Toa range will be shown by the local agents
of this Japanese company, Goldring Ltd. The
900 series can be fitted with a variety of inter -
Audix audio control console 46
44
 CALREC
INlJST1líL
AIIHDSIDIS
all part of the PSP
CALREC HAVE MOVED! Service
Calrec Audio Ltd., are pleased to
announce their move to larger and
better premises. Full details of our
complete range of microphones and
mixers are now available from the new
address :

Calrec Audio Ltd., You probably know us for our technical know -how
Hangingroyd Lane, and specialist distribution service.
Hebden Bridge, HX7 7DD But this month we're featuring something rather
Tel. Hebden Bridge 2159 unusual.
These spray -on aids include lubricants such as
MS4 grease, degreasing and cleaning solvents,
anti -static /anti- tracking sprays and a freezing
agent for the quick tracing of faults.
The latest is an electronic protective lacquer
WOW and FLUTYEN METERS with a very wide range of applications.
The demand was such that it had to be created
ME 105 and produced at very short notice.
They're all described in our Catalogue No. P 16.
Why not send for your copy now?
And don't forget our vast stock of other products -
audio, circular, rectangular panel /rack,
printed circuit and co -axial connectors .... all
kinds of test components .... cables to
European and USA standards .... et cetera.
Illustrated is the ME 105, the very latest type of Wow
and Flutter Meters manufactured by Woelke Magnet -
bandtechnik, Munich, Germany, and distributed
exclusively by us in the U.K. Anyone concerned with
the most accurate measurement of drift (down to
plus/minus 0.1 %) and wow and flutter (down to plus¡
minus 0.03 %) will be interested in the ME 105, ITT Cannon Authorised Distributors
available from April onwards. Fuller, final details on
228 PRESTON ROAD, WEMBLEY,
application. MIDDLESEX HA9 8PB
Telephone: 01 -904 9521 (5 lines)
Cables: PSPEL Wembley
LENNARD DEVELOPMENTS LTD.
206 CHASE SIDE, ENFIELD, EN2 OQX PSP ELECTRONICS LTD
MIDDX. Tel. 01 -363 8238

STUDIO SOUND, APRIL 1973 45

 SOUND '73 PREVIEW model of some 87 mm diameter -comparable Ditton range, of which the largest is the 66
with a tennis ball. These might have applica- Studio Monitor. Frequency response is des-
tions in tetraphonic audio though no further cribed as `substantially level' from 25 Hz to
changeable octal -based plug-in modules to data is available beyond a price tag of £9.50. 30 kHz, power capacity being 80W into 8 ohms.
match any likely source. The BS -367 loud- SNS Communications are to display their From Chymes Audio, a claimed `first': their
speaker is also being introduced and takes a PA12/40 six input four output mixer/amplifier. £117 audio mixer with integrated lighting drive
spherical form suitable for ceiling suspension. Two low impedance microphone inputs are unit. Chymes recently supplied a quadraphonic
Two eight track cartridge background music incorporated in addition to an input switchable discotheque system to the Sindlesham Mill
machines, one for rack mounting, the other between microphones, grams or tape. Separate country club, Berkshire, and examples of their
complete with power amplifier, are to be gain controls are fitted to the three main dj console systems will be on display. Power
demonstrated. Goldring will be found on channels with master bass and treble tone amplifiers are available from £79 (2 x 100W)
stands 41 and 42. controls giving 15 dB cut of boost. Also on and £147 (2 x 200W). These, Chymes consider,
Prolific seems the word for Millbank Elec- show will be the Strauss range of public offer the best performance /price ratio at the
tronics who plan to announce over 40 complet- address loudspeakers. Models from this range high quality end of the discotheque market.
ely new products at Sound '73. These will are illustrated below together with the Chorale Among microphones and accessories on the
include a new family of integrated and power entertainment mixer/amplifier. The latter Keith Monks stand, a wide selection of floor
amplifiers forsound reinforcement applications. features six inputs with individual slide faders. and table stands including the MSPA /B
Cannon, DIN and CSA connections will be Each input channel has bass, treble and floor and versatile SC/1 side clamp.
offered, all models conforming fully to Euro- reverberation controls. Price is from £455. Last but not least, the staff of STUDIO
pean electrical standards. Another amplifier Illustrated above, a largely self -contained SourID will exhibit themselves on stand 43.
series has been designed for recording studios public address system to be shown by Trusound David Kirk will attend Tuesday, John Dwyer
while yet another is being aimed at single Manufacturing. Model TPA20 operates from Wednesday and Thursday.
applications such as paging and fire alarms. either mains or internal batteries and has inputs
An eight track continuous playing cartridge for 30/50 ohms (100 uV for full output) or 500 AKG EQUIPMENT LTD, Eardley House,
machine is to be marketed as a background mV at 250k ohms microphone. Output power 182 Campden Hill Road, London W8
music source. This will be available in single Phone : 229 3695
is specified as 10W rms with an additional 10W Representative: P. J. Eardley
and double transport forms. rms available from an extension loudspeaker Stand: 11
Two electret microphones from Sennheiser feed. Retail price is £85.67.
should attract interest on the Hayden Labora- PSP Electronics, based in Wembley, plan to ASTRONIC LTD, Dalston Gardens, Stanmore,
tories stand. Since no high voltage polarisation show a comprehensive range of connectors and Middlesex, HA7 1BL
is needed, the entire microphone electronics are accessories including Cannon XLR and -per- Phone: 2042125
incorporated in the unit head. MKE201 is an haps better known in the air than on the Representative: G. H. Gray
omnidirectional model priced £28.50 while ground -Hellerman-Deutsch. Also a new Stand: 15
MKE401 is a £33.25 supercardioid. Hayden range of aerosol packed cleaning and lubri-
recently obtained the agency for Isonetta AUDAC MARKETING LTD, Trinity Works,
cating products. Trinity Lane, Wareham, Dorset
loudspeakers including a miniature spherical On the Celestion stand, speakers from the Phone : 092 95 2977
Representative: W. E. Armstead
Stand: 12
SNS Chorale mixer/
amplifier and Strauss AUDIX BB LTD, Bentfield End, Stansted, Essex
loudspeakers
Phone: 027 971 3132
Representative: C. J. Billet
Stand: 26
BEYER DYNAMIC (GB) LTD, 1 Clair Road
Haywards Heath, Sussex
Phone : 0444 51004
Representative: S. Duer
Stand: 16

CANADIAN INSTRUMENTS AND ELEC-

TRONICS LTD, 35 Waverley Street, Nottingham
NG7 4EB
Phone: 0602 71157
Representative: F. K. Watts
Stand:9
CTH ELECTRONICS, Somersham Road,
Industrial Estate, St Ives, Hunts, PE17 4LS
Phone 04806 4388
:

Representative: C. T. Heinlein
Stand: 4
CHYMES ORGANISATION LTD, 320 Barkham
Road, Wokingham, RG11 1BR
Phone : 0734 1970
Representative: C. Smith
Stand: 31
S. B. DAVENPORT LTD, 113 Graham Road,
Wimbledon, London SW19
Phone : 540 2266
Representative: G. W. Aggett
Stand :6

EAGLE INTERNATIONAL, Precision Centre,

Heather Park Drive, Wembley, Middlesex, HAO 1SU
Phone: 9030144
Representative: W. J. Morrow
Stand: 35
48
46
 A SELECTION FROM OUR WIDE RANGE OF MICROPHONE STANDS, SEE THESE AND
OTHERS AT THE 1973 A.P.R.S. EXHIBITION, SONEX 73, AND HANOVER FAIR

BSI /B Banqueting Stand. 421b base. Matt

black finish. 20in max height. Stem may be
fixed upright or angled.
BS2/B Banqueting Stand. 71b base. Matt bla -k
finish. 29in max height. Stem may be fixed
upright or angled
SB'I
MSPA /B Angle Floor Stand. Matt black finish.
80in max height.

SB /I Stereo Bar. Matt black finish. IOin

long. in locking screws provided.

SC /I Side Clamp. Matt Hack finish. Adjust-

able for different tube diameters. ¡in
locking screw provided.

For further details write or phone_to:

BSI/B BS2/B MSPA r

KEITH MONKS (AUDIO) LTD

26 -30 READING ROAD SOUTH FLEET .HANTS
Telephone: Fleet 102 514) 7316 and 3566

A custom -built mobile 50 -way

**1.,.W1.
:1474 :.:N:V .=1,
.14; rip

`!'yTay;^!+*,.Ty.
CTH Sound Mixer...
f:'.°, i' á"`. i'"w 8',
iT...7pT, pTyTq,/TayT!
i"'.. A"
The photograph shows the 50 -way trolley -mounted console of a
.

er_
complete sound distribution and mixing system recently com-

* pleted to special order. Ideal for either studio or location work, it

T4-14"4.1.
operates either from :mains or 12 volt battery and incorporates a

jack field and two integral 30 watt power amplifiers.

We are always pleased to design and manufacture to special
order, but the standard range of CTH Mixers already meets many
studio requirements, covering single or multi- output models with
up to:100 input channels. CTH also manufacture a range of
modular mixing units, consoles, distributor amplifiers, studio
disc player units, speaker amplifiers, cable drums and many
other items of studio equipment.

GOELECTRONICS
Industrial Estate, Somersham Road, St. Ives, Huntingdonshire PE17 4LS. Telephone: St. Ives 64388 (0480 64388)
STUDIO SOUND, APRIL 1973 47
 SOUND '73 PREVIEW K. F. PRODUCTS LTD, Brookfield House, Hopes Representative: E. R. Howlett
Carr, Stockport, Cheshire Stand: 24
Representative: K. G. Faure
GARLAND G. H. & COMPANY LTD, 101 -105 Stand : 17 SHURE ELECTRONICS LTD, 84 Blackfriars
Nibthwaite Road, Harrow, Middlesex, HA1 1TF Road, London SE1 8HA
Phone: 427 3536 LUSTRAPHONE LTD, St George's Works, Phone: 928 3424
Stand 27 :
Regents Park Road, London NW1 8XG Representative: B. L. Denton
Phone: 722 8844 Stands: 2 and 3
GOLDRING MANUFACTURING CO. (GB) LTD, Representative: A. T. Waller
10 Bayford Street, London E8 3SE Stand: 49 SNS COMMUNICATIONS LTD, Tropical
Phone: 9851152 Works, 851 Ringwood Road, West Howe,
Representative: G. Sharp MACINNES LABORATORIES LTD, Stonham, Bournemouth, Hants
Stands: 41 & 42 Stowmarket, IP14 5LB Phone: 020 16 5331
Phone: 044 971 486 Representative: D. A. Fisher
GRAMPIAN REPRODUCERS LTD, Hanworth Representative: I. Marshall Stand: 18
Trading Estate, Feltham, Middlesex Stand: 38
Phone: 894 9141 SON ET LUMIERE EQUIPMENT LTD, Ide Hill,
Representative: R. Denham MILLBANK ELECTRONICS GROUP, Bellbrook Kent
Stand: 21 Estate, Uckfield, Sussex Phone: 073 275 454
Phone: 0825 4166 Stand: 7
Representative: A. Walker
GULTON EUROPE LTD, The Hyde, Brighton,
Sussex BN2 4JU
Stands: 19, 20, 33 and 34 STANDARD TELEPHONES & CABLES LTD,
Private Communications, Foots Cray, Sidcup, Kent
Phone: 7302191
MONKS, KEITH (AUDIO) LTD, 26 -30 Reading Phone: 300 7788
Representative: Mr Smith Road South, Fleet, Nr Aldershot, Hants Stands: 22 and 23
Stand: 13
Phone: 02514 7316
Representatives: T. K. Monks, P. A. Cooper TRUSOUND MANUFACTURING LTD, Crittal
HAYDEN LABORATORIES LTD, Hayden House, Stand: 6 Road, Industrial Estate West, Witham, Essex
17 Chesham Road, Amersham, Bucks Phone: Rivenhall 4101
Phone: 024 03 5511 PSP ELECTRONICS LTD, 228 Preston Road, Representative: T. I. P. Baldwin
Representative: K. E. Owens Wembley, Middlesex Stand: 50
Stand: 5 Phone: 904 9521
Stand: 10 WESTREX CO LTD, 152 Coles Green Road,
JOHNSON BRODY LTD, 394 Noitholt Road, London NW2 7HE
South Harrow, Middlesex ROLA CELESTION LTD, Ditton Works, Foxhall Phone: 542 5401
Representative: Peter Walker Road, Ipswich, Suffolk, IP38JP Representative: E. A. Hawkins
Stand: 28 Phone: 0473 73131 Stand :1

INFORMATION STAND

w r '-1 C
z 18 17 16

SNS COMMUNICATIONS K F PRODUCTS

BEYER
zw Emi DYNAMICS
15

ASTRONIC
19 20 21' 22 23 24 26

ROLA
STC AUDIX 14
CELESTION
LING
WESTREX MILLBANK DYNAMIC
ELECTRONICS SYSTEMS
34 GROUP 33 32 31 30 28 27

BYAS JOHNSON
MOSELEY BRODY GARLAND

SHURE 13
GULTON
35 36 37 38 39 41 42
EAGLE Mc INNES GOLDRING
INTER- LABS. MANUFACTURING Co.
NATIONAL 12

50 49 48 47 46 44 43 AUDAC
CT.H MARKETING
TRUSOUND LUSTRA- STUDIO
PHONE SOUND
11
5

HAYDEN
LABS
AKG
6 7 10
MIDLAND CANADIAN?
K MONKS
INSTRU- R.S.P.
& S B DAVENPORT SON ET LUMIERE (SOUND
MENTS

48
 What makes a console great?
In aiming for creative expression, producers quad and stereo facilities, overdub facilities,
and musicians make great demands on a con- four separate headset or cue busses with master
sole and its operator. The key to a successful level controls, and a comp ete patch bay with
sessior is the ability to satisfy these demands jacks for over three hundred separate circuits.
quickly and easily.
The exceptional quality and reliability of its
A great console . . the MODEL 2416 for ex-
.
components means a conscle that consistently
ample.. . has the built -in flexibility and ver-
. delivers fine performance under the most de-
satility to be responsive to the wide range of manding conditions.
dynamic requirements encountered in studio
For a look at the MODEL 2416 and a complete
applications. The MODEL 2416 provides up to
28 inputs, each with the Model 550 three knob
description of its features, contact us today.
equalizer, four echo sends, three position high- Meanwhile, start thinking cf the great things
pass filter, channel phase reverse, switchable you'll be able to do with it.
mike -pad and gain control, panner, two inde-
pendent cue feeds and input solo. There are
AUTOMATED PROCESSES, INC- -
sixteen metered mixdown busses. simultaneous 80 MARCUS DRIVE, MELVILLE, NEWYORK 11146.516- 694-9212

i
 LAST MONTH, consideration was given to distortion can be permitted before acoustic
the methods of measuring the harmonic distor- roughness becomes apparent. Von Bekesy, in
tion content of a sinusoidal waveform. Ultima- a large number of tests on the relative rough-
tely these methods of measurement are the only ness measures of one frequency beating with
ones which are consistent enough to be used in another, showed that roughness is at a maxi-
comparing one tape system, amplifier or loud- mum when one frequency is about 50 Hz away
speaker with another. However, such methods from the other (see fig. 1). Furthermore, the
leave a number of questions unanswered, the roughness increases to a maximum when the
most important of which is: What figure is frequencies are around 3 Hz, and appears to
good enough for the distortion of a piece of be smaller at lower frequencies -which is in
equipment? Without an objective function, accord with general experience. When the
there is no way of determining whether a total difference between the two frequencies increases
harmonic distortion content of, say, 0.5 per or decreases from 50 Hz, the roughness appears
cent is good enough. The only objective to diminish.
function as yet developed for evaluating the
performance of an amplifier or loudspeaker is Measuring 'roughness'
an aural test and this inevitably introduces a The work of Von Bekesy in the mid 1950s
subjective evaluation. While subjective summarised many other workers' efforts,
measurements are disliked by many engineers, particularly those who tried to measure rough-
a vast amount of work has been performed in ness by two frequency methods.
acoustic measurements and some consistent Hilliard described a method of measuring
results have emerged. roughness or `intermodulation distortion' in an
Firstly, a trained listener finds higher order article in Electronics (July 1946) which was
harmonic distortion more objectionable than subsequently adopted by the Society of Motion
lower order harmonics. This may in part Picture and Television Engineers and is now
account for the observation that a Class A usually known as the SMPTE method. The
power amplifier sometimes sounds better than two frequencies used are a low frequency signal
a Class B amplifier of comparable total distor- (Q) of about 60 Hz and a high frequency signal
tion content. Class A amplifiers generate (P) of about 3 kHz. Q is arranged to have four
second and fourth order harmonics whereas times the amplitude of P. The two signals are
Class B amplifiers generate third and fifth order combined and passed through the amplifier.
harmonics. Wigan, in an article in Electronic A high pass filter follows the amplifier which
Technology (April 1961) proposed using a rejects signal Q. The modulated high frequency
weighted measurement to take account of signal consists of P, plus the products (P+Q),
higher order harmonics being more objection- (P Q), (P +2Q), etc. These signals are now fed
able than lower order harmonics. through a detector and low pass filter so that
P is removed leaving only the modulation
Tolerable distortion products (fig. 2) which are then read on a
Secondly, based on a single 1 kHz sinusoidal millivoltmeter.
waveform input, a trained listener can tolerate It can be seen from the work of Von Bekesy
a second harmonic distortion level of about that this measurement is not evaluating what
1 per cent before detection and the figure for the ear detects as roughness since the frequency
the third harmonic is about 0.4 per cent. difference between the two signals is too great.
Thirdly, the trained listener can detect what Therefore the method does not measure the
has been called the `acoustic roughness' of subjective impression of roughness though it
complex waveforms. This appears to have a does have its uses in loudspeaker testing. One
far lower distortion content than the minimum of the most difficult aspects of loudspeaker
detectable on a single sine wave. design is to reproduce bass cleanly and it is

Distortion: The last point has led to the development of

methods which attempt to evaluate complex
waveform distortion. Fundamentally the
problem is this: a sinusoidal waveform of one
here that most `tricks' are employed to give a
reasonable bass output, especially in small
enclosures. While the distortion of a single
low frequency signal may not be immediately

Cause frequency, when passed through an amplifier,

will at the output contain harmonics. Another
frequency will be similarly affected and, when
obvious, the distortion level may be sufficient
to intermodulate higher frequencies causing a
particular roughness effect.

and both frequencies are introduced, one frequency

will amplitude modulate the other. This is of
no consequence as far as the fundamental
The nature of this roughness differs from that
caused by an electronic process such as
amplification; instead, the distortion arises

Effect frequencies are concerned since normal complex

waveforms occur in this manner. However,
modulation also occurs to the harmonics pro-
ducing in effect sidebands of the fundamental
from the fact that the low frequency is modula-
ting the higher frequency and therefore, as the
cone moves forwards and backwards at a low
frequency, the high frequency is carried on this
TONY EDEN frequency. These sideband frequencies occur cone movement. A stationary listener finds
as the sum and differences of the fundamentals that the higher frequency is changing in fre-
In the second of two articles, as well as other more complex relationships. quency; an effect first observed by Doppler. A
the author attempts It is the occurrence of these sideband frequencies changing high frequency in the presence of a
an objective answer to the which produces what is known as acoustic lower frequency occurs as one form of rough-
question 'How much roughness and the magnitude of the roughness ness and is often called Doppler distortion.
distortion is tolerable ?'. The is determined by the depth of modulation of This form of distortion can be minimised by
the carrier signal. In turn, the depth of modula- using two or three speaker units each handling
usefulness of an tion is a function of the harmonic distortion a different part of the frequency range. Also, a
oscilloscope in evaluating content of each of the frequencies being con- totally enclosed cabinet is often used in which
distortion is emphasised sidered. Thus, while harmonic distortion gives the stiffness of the enclosed air at low frequen-
and several methods of one measure of roughness produced by an cies (30 to 100 Hz) is made equal to the
measuring amplifier distortion amplifier or loudspeaker, what it does not do mechanical stiffness of the diaphragm
outli ned. is give any indication of how much harmonic suspension.
50
 given rise to the general acceptance that the frequency is put directly on the vertical plate of
FIG.1 VARIATION OF ACOUSTIC
harmonic distortion level in an amplifier should an oscilloscope and the other frequency on the
ROUGHNESS WITH BEAT RATE
HIGH
lie below 0.1 per cent throughout the major horizontal plate, then the various waveforms
portion of the audio range (100 Hz to 10 kHz). that result are shown in fig. 5.
It was mentioned last month, and is worth Two other methods are used for testing the
R.1. reiterating, that an oscilloscope can be extremely roughness of amplifier responses. If white
useful in evaluating many forms of distortion. noise is applied to the input of an amplifier in
MIN

`\
Intermodulation is a good example. If the which a band of the noise is suppressed, then
I SMPTE method is used to measure distortion, the output from the amplifier can be measured
the oscilloscope trace may well appear as shown to ascertain if there is any signal present in the
in fig. 4. By making use of the graticule on the suppressed region. If this is the case, then inter -
oscilloscope, a quantitative value can be placed modulation distortion is present in the ampli-
' MIL BOOHz`320OHz
on the distortion level. Alternatively, if one fier. This test is particularly useful to show the

LOW
FIG. 2 SMPTE METHOD OF MEASURING INTERMODULATION DISTORTION
D 20 L0 60 80 100 120 140 160 180
BEAT RATE IN Hz

OSCILLATOR
'P'

Hence, under conditions where the low REJECTS

REJECTS P
frequency distortion level may be high, the 13KHzI METER
SMPTE method can give useful design
information.
Scott, working at the General Radio Corn-
pany, described another method of measuring
OR IDGE
AMPLIFIER
LOUDSPEAKER
UNDER TEST
OR HIGH
PASS
FILTER
DETECTOR
LOW
PASS
FILTER
B

o
roughness using two frequencies. This article i 1
SIGNAL HERE SIGNAL HERE CONTAINS SIGNAL HERE
appeared in Electronics in January 1945 and OSCILLATOR
CONTAINS +OI,IP -GI.
O,IP CONTAINS ONLY
the method was later adopted by the Inter- P.O (P +20),(P -201 ETC. INTERMODULATION

national Telephonic Consultative Committee PRODUCTS

(CCIF) and is now named after that organisa- (60Hz1

SIGNAL AT B IS MEASURED AS A PERCENTAGE OF A,
tion. Two signals of equal amplitude (P and TO GIVE INTERMODULATION DISTORTION.
Q), but with a small frequency difference
(usually 50 Hz), are combined and fed into the
amplifier under test. The resultant signal then
passes through a low pass filter to reject the
P and Q signals (fig. 3). The even -order inter - F!G. 3 CCIF METHOD OF MEASURING INTERMODULATION DISTORTION
modulation products (P -Q), 2(P -Q), etc, are
passed by the filter and measured on a milli -
voltmeter. This method does not measure the OSCILLATOR
'P'
odd order harmonics 2P -Q, etc, for which a
wave analyser would be required. The method REJECTS P,0
IP- 2O1,1P +201 ETC
represents a good measure of subjective rough- ME:ER
ness since the two frequencies are of equal AMPLIFIER A LOW PASS
BRIDGE
amplitude and both frequencies close together. UNDER TEST FILTER

Typically the frequencies used are 3 kHz and

3.05 kHz.
As a guide, the ear would detect roughness TSIGNAL ERE SIGNAL HERE SIGNAL HERE
as being apparent using the SMPTE method OSCILLATOR tt
CONTAINS CONTAINS P,O, CONTAINS
'a'
when the lower frequency has a distortion P.O (P- 01.(F +O) IP- 01,2(P -01
IP- 201.1P +20) ETC ETC.
content of about 5 per cent. However, the ear
can detect roughness using the CCIF method SIGNAL AT B IS MEASURED AS A PERCENTAGE OF A,
when the frequencies have distortion levels of TO GIVE INTERMODULATION DISTORTION

about 0.2 per cent. The latter test has probably

distortion content of the high frequency end

FIG. 4 USE OF OSCILLOSCOPE TO ESTIMATE DISTORTION BY THE SMPTE METHOD of the amplifier. For example, if noise is
F = 60Hz t = 3KHz
applied above (say) 15 kHz and the amplifier
output measurement is tuned to the 1 to 4 kHz
region (the most sensitive part of aural spec-
trum) then the level of output gives a good
indication of the intermodulation that has
occurred above 15 kHz.
MAX
The final method to be described for measur-
ing distortion of amplifiers is very simple in
concept. A signal (single or complex) is applied
to the input of an amplifier and the amplifier
output is attenuated and compared with the
input signal. The object is to balance, as far as
RESULTANT SIGNALS AFTER PASSING THROUGH HI -PASS FILTER possible, the input with the output signals
thereby (in an ideal case) resulting in zero out-
7. DISTORTION _ MAX. - MIN. x 100
put after the balancing network. Since phase
MAX.+ MIN.

52
STUDIO SOUND, APRIL 1973 51
- DISTORTION FIG. 5 GAIN DEVIATION METHOD FOR ASSESSING DISTORTION

PHASE
I00Hz
shifting occurs in the amplifier, some form of SHIFT

compensating network is required (fig. 6). By

making a phase shift network that compensates SUM
INPUT

for the amplifier signal throughout the audio RRIOGE

range, the dynamic distortion present in an)

musical item after amplification can be tested. AMPLIFIER HIGH PASS
Y INPUT
ONHz
UNDER TEST FILTER

Transient distortion
Another form of distortion which arises in a TYPES OF OSCILLOSCOPE TRACE
rather different manner but results in the same
acoustic roughness is transient distortion. IiI lI II0 I111111 1 I II l II II lIl
Transient distortion is present in amplifiers to
a small extent but is a much more important
consideration in loudspeaker design. The
problem here is that a large quantity of enerp 1111111111111111111I111111111
is required to make the loudspeaker cone mo (a) (b) k)
Thus there is a delay in making the cone mote. NO HARMONIC DISTORTION Und HARMONIC DISTORTION 3rd HARMONIC OISTORTIOH
due to its inertia, when a pulse is applied.

FIG. 6 DYNAMIC METHOD OF TESTING AMPLIFIERS

OSCILLATOR
PROGRAMME
SOURCE
OR

N 4P.' AMPLIFIER
UNDER TEST

OUTPUT
FINE
PHASE ANALYSER
AMPLIFIER NRIOGE
ADJUST (METER OR
ADJUST
AMP +SPEAKER)

Similarly, when that pulse stops the cone Speech (especially male) is a good test of the is to be used for tape distortion measurements.
continues vibrating. This can give rise to many low /middle frequency range, an area where Here the response can be 3 dB down for a
forms of 'hangover' resulting in roughness. distortion (or coloration) is usually most bandwidth deviation of 6 Hz (which is indepen-
One method of testing loudspeakers has been objectionable. An instrument such as a dent of frequency) and therefore measurements
to apply bursts of tone to the loudspeaker and harpsichord provides a very good test for the become extremely difficult at frequencies above
observe the results on an oscilloscope. The transient response of a loudspeaker as the about 5 kHz. One method of overcoming this
loudspeaker with low transient distortion will attack and decay times can be extremely fast. problem is to use a tuned amplifier but tuned
commence vibration very quickly and likewise A full choir provides a very useful test for the over a fairly wide frequency spectrum such as
will cease very quickly when the tone burst power handling capabilities of the loudspeaker, one-third octave. In this way frequency varia-
ceases. This is a very useful method of testing as well as a very good test for the 'cleanness' tions of the fundamental can be catered for
at the development stage of a loudspeaker but of soprano voices. Finally, certain pieces of and such a facility is fitted to the B & K
does not of course give any quantitative infor- organ music provide a very good test on the spectrum analysers. Intermodulation distortion
mation about the loudspeaker performance. quality of deep bass and this test will usually measurements are possible on tape systems but
Considerable research has been undertaken reveal objectionable intermodulation distortion. are infrequently made and even less frequently
over the last two decades (much of it by the In a few more years it should be possible to quoted. Any such tests are usually restricted
BBC) to produce loudspeakers with reliably analyse the quality of a loudspeaker as it relates to the amplifiers only. More rigorous distortion
low distortion at all power levels. It is a tribute to the human brain. tests on tape machines would quickly differen-
to the BBC Research Department that the Distortion measurements on tape recorders tiate between machines which apparently have
results of their development work are incor- can be complicated by the effects of wow and the same frequency response and noise level.
porated into so many loudspeakers used for flutter on the figures. Wow and flutter The most widely quoted measurement is the
monitoring purposes. In nearly every publica- are. of course, a source of distortion giving an maximum single frequency signal that can be
tion on loudspeakers, the final evaluation of effect on a single frequency similar to Doppler put on tape for a 2 per cent distortion level.
the quality of a speaker is dependent upon distortion in loudspeakers. The simplest single What happens below this level is rarely dis-
aural tests. The reason for this is that the frequency method of measuring distortion on closed. The signal can be distorted by the tape
single frequency test will yield some informa- tape systems is to use a distortion factor meter. mechanics, the bias oscillator, the tape medium
tion on the distortion level of a speaker, a two - It is difficult to make accurate measurements itself, and the electronics.
frequency test will yield rather more informa- to much below 0.5 per cent because the It is hoped that this rather brief survey of
tion, but speech and music contain very much frequency is being modulated (fm) by the wow. the methods of measuring distortion will help
more complex waveforms than the first two Hence accurate tuning of the 'notch' becomes to put into perspective the advantages, dis-
tests can possibly evaluate. Hence the final impossible. The problem is usually not too advantages and limitations of the various
assessment of the quality of a loudspeaker is bad because the notch is sufficiently wide to techniques, as well as to indicate the necessary
usually made by listening critically to different allow for small variations in the fundamental. interpretation if meaningful figures are to be
types of program material. The problem is much worse if a wave analyser obtained.
52
 'TELEF/.
N

OFF

What is TEL
'.me real Hi if existing
"r
conjunction with Hi -Fi and Audio systems for providing high quality
625 line television. television sound reproduction. No direct connection to the T.V. is
T.V. Studios transmit superb quality but skimping in the sound required. the coupling being effected by an inductive pick -up.
section of the receiver means low -f sound. Telefi is complete in a handsome natural teak veneered case 7; x "'

Celestion Telefi changes all this - simply coupled to most T.V 5q "x 2ä "approx
receivers the first T.V. music you hear through Teleti will convince "The Telefi is a very worth while device and will give greater overall
you the dramatic improvement is what you have been waiting for. enjoyment than the T V. manufacturers normally provide -John Gilbert
Telefi a remarkable innovation e, . tit Celestion for use in 'The Gramophone

Also send for details of the complete range of Celestion Loudspeakers

Celestion ROLA CELESTION LTD.

DITTON WORKS, FOXHALL ROAD, IPSWICH, SUFFOLK IP3 8JP

Series 7
Modular Sound Systems

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FEETHAM MIDDLESEX
TELEPHONE 01 -894 9141
GRAMS REAMP FEETHAM

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Prime mover for jingles, NAB 2V to indicate OdB: Exclusive automatic LED over-
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and Q8 cartridges, machines
instant start solenoid MEG 120 Constant Current Recording Amplifier.
MEG 130 Master Bias Oscillator and Buffer Amplifier.
operated. MEG 140 Slave Bias Amplifier for multi -channel recorders.
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Modular electronics for multi -channel recorders and Studio
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Oldershaw Mews, Maidenhead 8 HALE LANE, LONDON NW7 3NX England
OVND
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STUDIO SOUND, APRIL 1973 53

 IN AN EXCELLENT article in the December a few ohms, plus the dc resistance of a trans-
STUDIO SOUND, John Bowsher and H. A. O. former's secondary where applicable.
Wilms gave a most interesting history of the With most equipment using 1:1 ratio line
use of the dBm and made some suggestions for output transformers, the output impedance of
clarification in the use of the various dB refer- a few tens of ohms is in my experience almost
ence standards. While in general agreeing with entirely due to the dc resistance of the trans-
the various points raised, I feel that further former windings. The input impedance of
clarification might be of interest. I would also almost all industrial equipment is now 10k
like to propose some new standards myself. ohms or over, although frequently the manu-
Though agreeing that the 0 dBm reference facturers specify that the equipment should be
point was originally designed to represent a driven from a. source of 600 ohms or less in
power level of 1 mW dissipated in a 600 ohm order to avoid input transformer reactance
resistance or impedance, and that dB relative compöiients having a detrimental effect on
to this originally referred to variations in power performance. It therefore seems quite pointless
level, I have always regarded the unit as a to consider power gain of amplifiers used in
convenient voltage reference of 0.775V. I modem recording studios and it would there-
would suggest that 99 per cent of engineers fore be reasonable to consider the adoption of
involved directly in the sound recording not only a new unit but a new voltage reference.
industry nowadays also regard the unit in the I therefore propose the adoption of the dB(V)
same way, although line communication as such a reference, 0 dB(V) representing a 1V
engineers and some film audio engineers may voltage level anywhere in the system. Most
well continue to use the unit as a power refer- studios work to a nominal peak line level
ence. Provided that the output source referred to as +8 dBm which, in old termin-
impedance of equipment was always 600 ohms ology, should perfiaps more correctly be
and the input load impedance was also 600 referred to as 1.97V. If this same level were
ohms, the unit could perfectly easily be used referred to as 2V, i.e. +6 dB(V), the error
for voltage references without any misunder- would only be 0.2 dB which is of no real
standing. I use the word `was' because almost significance.
all studio audio equipment is now normally After considerable research I have ascer-
supplied with a low output impedance and a tained that some studios peak approximately
high bridging input impedance, although 600 6 dB above 320 nWb /m on their tapes even
ohm impedances can usually be supplied for when Dolby noise reduction systems are used.
the diehards. Many manufacturers, however, For interchange purposes, therefore, it would
still completely misunderstand the 600 ohm line be extremely convenient if 0 dB(V) could be
theory. While supplying input termination standardised as a level equivalent to a recorded
resistors to make up the input impedance to flux of 320 nWb /m. This would in particular
600 ohms, they then frequently terminate the tie in precisely with current BBC practice where
output with a parallel 600 ohm resistor, rather a peak of six on their ppms corresponds not
than building out the output source impedance only to an output voltage of 1.97V but also a
to 600 ohms by adding a series resistor allowing recording level on BASF LR56 tape (used
a 600 ohm source. frequently by them for stereo recording) of
My own experience of confusion in relation 640 nWb /m (6 dB above DIN reference level).
to dB as power gain or voltage gain was in 1958 A standard line -up level of four on a ppm
when I purchased two STC microphone ampli- would therefore correspond to -2 dB(V). In
fiers which were normally supplied with 600 such a system a ppm reading of 4.5 would
ohm input and output impedances floating correspond to a tape flux level of 320 nWb /m
balanced. The amplifiers had switched gains and 3.25 would then correspond to Ampex
with positions labelled 40, 50, 60 and 70 dB operating level, also referred to as `Dolby level'.
gain. Since at the time all my mics were of 30 Once again it is convenient that 3.25 on a ppm
or 50 ohms impedance, the units were ordered happens to coincide with BBC stereo line -up
from STC to work with such mics and to feed tone.
equipment with 600 ohm input termination The eventual adoption of these proposed

The dBm resistors. I remember being baffled for a while

because I had measured the voltage gain of the
equipment on each switched position some
levels would necessitate changes of gain in
many units but, under almost all circumstances,
preset gain controls will be found to have more
8 dB higher than stated by STC. Since 8 dB than enough gain in hand.
change of voltage corresponds to an impedance There are obviously a number of snags in

dB(V)? change of approximately six times, the input

impedance of the STC amplifier would there-
fore have been approximately 100 ohms, which
such a change, the main one being the necessity
of replacing scales on test equipment having
references to 0 dBm equalling 0.775V. Much
would have tied in with the specification. The test equipment, however, including that made
ANGUS McKENZIE necessity of loading the output with 600 ohms by B & K, is scaled in dB(V). In any case,
in order to achieve correct working levels, instruments such as the Level microvoltmeter
The decibel is arguably the most however, brought considerable complications. series are, by the die-hards' standards, incor-
frequently misused and the The most serious of these was the necessity of rectly scaled in dBm, since their input imped-
least understood 'unit' in using either trap valve amplifiers to feed ances are usually at least 1M ohm. Also, they
electronic engineering, various pieces of equipment, or hybrid trans- measure voltage rather than power. A change
despite hard competition formers which split the output power to of scale to dB(V) would put right this error for
from the Watt. different loads. It was not always economic all, and bring the instruments up to the same,
Responding to H. A. O. Wilms' and to allow valve equipment to give both a high scaling standard as B & K.
voltage clipping level and a low source Alternatively, as John Bowsher points out
J. M. Bowsher's theoretical impedance since this amounted to an ability to the scale should be referred to in dB(V.7), a
article published in our give considerable power. With modem unit which I strongly object to as nobody would
December issue, the author transistor equipment, however, it is easily remember to add the `.7'. New scales would
suggests practical definitions possible to design all equipment to give levels not be expensive to produce and would be very
of the dBm. of above 7V from source impedances as low as much easier to correlate. Amplifier input
54
 sensitivities are often given in mV which can failings and giving a truer indication of peak
be quickly referred to in dB(V), whereas rapid line levels? FET Condenser microphones with phantom
mental calculations translating mV into dBm It is fair to add the VU meters used across feeding (9v /12v /48v)
or vice versa can easily result in 2.2 dB being FET Condenser microphones with parallel
lines driven from low source impedances (i.e.
absentmindedly added or subtracted in the feeding (9v /12v)
100 ohms or less) do not add significant
wrong direction. Capsules with single directional pattern
distortion. The advantages of effectively lower- Capsules with several switchable direc-
I discussed all the above suggestions with ing the absolute peak voltages in systems also tional patterns.
John Bowsher and he agrees in principle with include the possibility of using considerably
them. The matter was a1s§o raised at a recent Changeover of the directional pattern
lower ht rail voltages in equipment, with the is effected by altering the
AES meeting held at the lEE where most subsequent saving in cost of components. mechanic -acoustic elements of the
people who contributed to the discussion also Lower power levels would be involved and capsule. By this means the
agreed in principle. One rtiêmher, `of the emergency battery supplies such as two PP9 switchable capsules need only one
audience, however, insisted that ail dBm in series (18V) would be ample for many diaphragm, thus avoiding
should always be used for power level references falsifying phase effects even at
purposes. the highestfrequencies, (German
and further stated that he preferred to see all I realise that all the above suggestions are and foreign patents).
amplifier gains as power gains. I replied that rather controversial but feel that such standards Further special features include:
this seemed unnecessary since very few engin- would be very convenient for many users. I Great modulation range
eers now were concerned with matching realise that referring a tape flux level to a line Very low harmonic distortion
amplifier impedances. I quoted the absurdity voltage may be impracticable, partly because over the entire frequency
of specifying the power gain of an fet capacitor of the VU meter, but I think that at least the range
mie amplifier having an input impedance of use of the dB(V) rather than the dBm can be Optimal focusing with the
several hundred megohms and an output pressure gradient
most seriously considered, leaving the dBm microphones
impedance of 200 ohms or so, and having a where it originally belonged -to the line Degree of focusing largely
voltage gain of unity. To avoid loading effects communications engineers. independent of frequency
I also pointed out that it would be most The VU meter design is now well over 30 For stereo recording
convenient to agree upon an international years old and, while in its early days it was by X/Y or M/S
standard that all output source impedances of remarkably sensitive (having approximately intensity principles,
studio equipment shall be less than 100 ohms, the stereo micro-
1.8V ac fsd with an impedance of 7.5k ohms), phones CMTS 301
and all input impedances greater than 10 k it could be greatly improved with current (p) and CMTS 501
ohms with the sole exception of microphone technology. It might be fairly simple to design are ideal, and
preamplifier inputs. For the latter it would be practical.
a meter of the same input impedance, but
reasonable to specify internationally lk ohms, using more efficient diodes, and a better
and for microphones to be designed to work magnetic system which could allow a sensitivity
into this impedance. In practice, normally all of 580 mV for 0 VU (which is also incidentally
professional microphones are designed for the voltage level proportionate to most B
optimum performance into 1k ohms. All system Dolby levels, as well as Dolby level on
equipment could also have performances my new suggested standard of 1 V =320 nWb /m.
specified with lk ohms input and output If the new standard reference impedance of lk
terminations. Under these circumstances, we In the heads of these
ohm could be used, this might be referred to microphones are two
would therefore have a situation where 0 dB(V) internationally as 0 dB(kf/), in which case the capsules, which can be
would equal 0 dBm as originally used, a power already suggested IEC standard of dB(mA) switched independently to
dissipation of 1 mW, but into lk ohms. This representing a reference of 1 mA would tally card ioi d- bi -omn i- directional,
nominal impedance is of course geometrically most conveniently. If most of these recom- one of which can be rotated
half way between 100 and 10k ohms in terms through 360° These capsules
mendations could be adopted, they would are switched mechanically
of loading. Input and output transformers finally realise Dick Swettenham's slogan `600 and possess only one
could be designed to work at all appropriate ohms is dead'. diaphragm.
impedances below or above 1k ohms respec-
tively, with no undue problems. Many manu-
facturers find it necessary to load a balanced
output transformer in order to obviate high
frequency ringing or peaking. The addition of
a reasonable number of 10k ohms input
impedance amplifiers would not materially
affect output levels since the output impedance
would be less than one -tenth of lk ohm. This
would end the 600 ohm legend. It is incidentally
worth noting that, whereas 600 ohms is not a
standard value of resistance, 100 ohms, lk ohm
and 10k ohms are.
The VU meter unfortunately presents a
Late news item r
A.V. Distributors
(London) Ltd.
problem. Not only is a 0 VU reference an SHORTLY BEFORE going to press, we were
awkward one but it has been normally regarded informed by Mr Ira Gale (Gale Electronics & 26Park Road, Baker Street,
as indicating Ampex operating level or Dolby
London, NWI 4SH
Design Ltd, 39 Upper Brook Street, London Telephone: 01 -935 8161
level. Most industrial machines have VU meter WlY 1PE) that he is organising an exhibition
amplifiers of variable sensitivity. It would of industrial audio equipment to run con- Please send mefurther details on Schoeps
probably be best to consider increasing their currently with Sonex '73 at the end of March. Condenser Microphones
gain by approximately 7 dB so that 0 VU could A bus will take visitors from the Excelsior Name
correspond to a voltage level of 4.8 dB(V), Hotel to Proson '73 at the Sheraton Hotel,
having established 0 VU as 320 nWb /m. With Heathrow, and back again. Admission will be Address
older equipment in which VU meters are free but by ticket only (available from Gale).
switched across 600 ohm source impedance It is understood that AKG, Amcron, Ampex
lines, most VU meters will be found to intro- and Audio Applications equipment will be on
duce distortion on to the line because of the show in addition to a Gale loudspeaker.
diodes used in the meter rectification. In such Contrary to rumour, STUDIO SOUND is in no
circumstances, would it perhaps be better to way involved with this event though we will SS4
consider a metering system not having such be represented at Sonex. L - - J
STUDIO SOUND, APRIL 1973 55
 COUNTY Cutter head suspension : automatic lower and lift
County Recording Service, London Road, stylus heater current switching depth of cut electric-
Hinfield, Bracknell, Berkshire. ally controlled and adjustable.
Tel : 0344 4935. Turntable speed: 16i, 45, 331, 78 rpm.
Turntable diameter: 40 cm.
Disc -cutting equipment and all ancillary units and Turntable weight: 18 kg.
services. A complete system could be supplied cost- Turntable vacuum: vacuum indexing for 18 cm /s
ing from £500 upwards, depending on requirements. 25 cm /s and 30 cm /s recording blanks.
Individual items are priced as follows: Leadscrew: servo controlled with varigroove.
Disc recording heads rebuilt, repaired and serviced All functions are actuated by push buttons which
-from £15 upwards. Stylus heater units -£25. are illuminated to indicate the function in operation.
Swarf extraction systems -about £100. Disc cutting Switching operations are carried out by solid state
equalisers with or without a monitor section-from circuitry mounted on plug -in printed circuit boards,
£100 upwards. thus avoiding the need for unreliable relay switching.
County make and supply styli for all types of cutter All pushbuttons and controls required for the opera-
head from £3 each. Heater windings are fitted to the tion of the lathe are grouped together on a control
styli for an extra 25p each. Disc cutting styli are panel. Separate instruments on this panel indicate
relapped at from £1.75 each. County Recording groove pitch, stylus current, depth of cut and peak
Services say they have neatly finished experiments programme groove modulation.
on a new stereo disc recording head. It is a moving The 406 mm diameter turntable is driven direct from
coil device which they hope to sell for about £750, a dc motor, servo controlled using a crystal
with the electronics, power amplifier, equaliser and controlled clock achieving a high degree of speed
so on costing a further £750. They hope to be able stability over a long period. The system is inde-
to convert suitable disc recorders to cut stereo for pendent of mains frequency.
under £2000, which will include mechanical over- The leadscrew is driven from a servo -controlled
haul, delivery and setting up in the client's cutting motor which may be adjusted manually to give a
room. In the near future they also hope to offer 18 wide range of grooves per centimetre. Varigroove
cm recording blanks for 40p each. is also incorporated in the same circuitry and its
signal is derived from an advance head on the tape
replay machine. The vari- groove signal is analysed
for programme level and frequency spectrum before
overriding the groove pitch set manually for the
MSR leadscrew motor. The vacuum line serves two pur-
MSR Electronics Ltd, Meeting House poses, namely collect swarf from a point directly
Lane, Balsa!! Common, Near Coventry, behind the cutting stylus and as a turntable vacuum
Warwickshire. for retaining the recording blank.
The cutter head mounting and suspension is inten-
Tel : 0676 32468. ded for the Ortofon stereo cutterhead type DSS661.
MSR series 1000 and 2000 disc cutting lathe The mounting also contains the stylus heating coil,
The MSR series 2000 and MSR series 1000 disc which is cut off when the cutter head is lifted, and
cutting lathes are designed to cut stereo and mono electronically controlled depth of cut.
records respectively. The system is intended to Groove pitch: continuously variable from 40 gpc
accommodate all standard record sizes and a range to 160 gpc for each turntable speed.
of four turntable speeds. Stylus heating: variable dc current up to 1A.
A control system which has the following functions Microscope: Nikon microscope 150 times magni-
is used to achieve semi -automatic cutting: lowering fication with calibrated graticule.
and lifting the cutter head; scrolling in and out at Metering: independent meters are used to monitor
predetermined diameters; adjustable timed marker groove pitch, depth of stylus cut and stylus current.
Programme Input: balanced floating 10k ohms.
Survey: groove; start stop of the tape replay machine and
so on.
The cutting system incorporates the Ortofon stereo
Presettable in onedB steps from -6 dBm to +6 dBm.
Monitor output: 100W rms per channel into 8 ohms

Disc cutting amplifier type G0701 /GE 701 and the complete
unit is housed in a floor standing console accommo-
impedance.
Programme metering: one ppm per channel
switchable to read programme input and other

cuttin
dating recording amplifiers and control logic
circuitry. functions.
Recorded velocity: peak cutting velocity 30 cm /s

equipmen Technical specifications

Cutter head mounting: intended for the Ortofon
stereo cutter head type DSS661.
Frequency response: measured on disc. t3 dB
10 Hz to 36 kHZ. ±1 dB 20 Hz to
Harmonic distortion on disc:
1
18 kHz.

kHz recorded at 25 cm /s peak. 2nd harmonic 0.4 ï;,

3rd harmonic 0.2 °,,
30 Hz recorded at 1 cm /s peak. 2nd harmonic 0.6 %,
3rd harmonic 0.2 ",,.
Intermodulation : different tones
6.6 kHz and 7 kHz 8 cm /s peak. 40 Hz = 0.07%.
12 2 kHz and 12.6 kHz 2.8 cm /s peak. 400 Hz 0.1%.

NEUMANN
Georg Neumann & Co, 71 Heilbronn
Neckar Fleinerstr. 29, Postfach 2120,
West Germany.
Tel : 8 22 75.
Agents: FWO Bauch Ltd, 49 Theobald
Street, Boreham Wood, Hertfordshire.
Tel : 01 -953 0091.
Disc recording lathe system V MS70
Components: Computer programmed automatic
groove spacing (pitch) and depth control, as a

Left: Neumann cutting system.

56
function of program material provides optimum and two stereo playback heads which provide both hght)): VMS 500 VA 1400 x 620 x 1370 mm.
utilisation of the record surface. the control signals for automatic pitch /depth control VG 400 VA 540 x 630 x 1950 mm.
Relay -less control system. and the modulation outputs for the cutterhead. SP172 100 VA 540 x 630 x 1950 mm.
Plug -in programmer; one for each record rotational Complement: SP272 100 VA 1400 x 620 x 1080 mm.
speed and diameter, all other functions such as Speckal AEG Telefunken M -15 magnetophon with MT 160 VA 810 x 670 x 890 mm.
lead -in and end groove diameters, basic -pitch, switchable 19/38 cm /s tape speeds. Weight: VMS 350 kg; VG 130 kg: SP172 125 kg;
automatic pitch control, lead -in, spiralling and lead - Four playback amplifiers. SP272 150 kg; MT 150 kg.
out pitch, concentric end groove, cutter lift delay Four switchable NAB /IEC (CCIR) playback equal- Disc cutting lathe system VMS70-mono/
and so on are programmed automatically. Re -cali- isers. stereo.
bration is not required. Preview head continuously variable preview distance With disc cutting lathe AM66, microscope Leitz
Amplifier rack to suit all tape and disc speeds. ZA36a, cutter head suspension SA66, depth of cut
This rack houses all of the electronics required for Optical sensor sends pulses on seeing leader be- control unit TE66, pick -up arm TA70 with magnetic
operation of the SX68 stereo cutterhead. tween selections and at the end of the tape to pro- stereo -pick -up, lead screw drive -unit VA66with echo
Components: vide fully automatic spiralling and lead -out grooves. device for elimination of echoes, drive control AS66,
RIAA recording characteristic equaliser (switch - Four VU meters with range switch. power supply NG70 and three program plugs
able). Stereo disc cutterhead SX68 (30 cm/33A rpm; 25 cm/33. rpm; 18 cm /45 rpm),
Cutterhead drive power amplifiers. In combination with the amplifier rack the dynamic vacuum chuck turntable ZA3, turntable drive motor
Circuit breaker: to protect the cutterhead against feedback cutterhead SX68 cuts stereo and mono SM8 /3 -A, lathe console ZT70 with wiring and suc-
thermic overload. records. tion installation, vacuum pump VP1 and control
Feedback amplifiers. amplifier SV66.
RIAA playback amplifiers (pick -up /feed- back). Technical specification Price: £11,530.
Monitor power amplifiers. Turntable rotation :Ise, 22;, 33f 45 rpm switchable.
, Amplifier system VG66S- mono /stereo
Cutterhead alignment module. Pressing diameters: 178, 254, 305 mm switchable. The VG66S contains one 48 cm rack SG66, one ampli-
Automatic high frequency limiters. Lacquer blank diameters: 178, 254, 305, 337, 356, fier component assembly VB66S, two monitor pre-
Mounting space and all connections provided for 406 mm switchable. amplifiers WV661C,two recording equalisers SE661C,
the tracing simulator TS 66 for reduction of tracing Tape speeds: 19 and 38 cm /s, others available. two cutter adjustment modules CE66, two feedback
distortion. Recorded velocity capability: 33 cm /s lateral. amplifiers GV66, four drive amplifiers LV66, two cir-
Programme controller SP 172 (48 cm version) Playing time at 33 rpm: programme dependent cuit breakers S166, one monitor control ÁR66, two
Programme controller SP 272 (console desk but 33 minutes not uncommon. monitor amplifiers AV66, two power supply assemb-
version) Frequency response: lies NS66 and one dummy cutterhead EW68A.
The programme controller is the heart of the tape - disc section: 40 Hz -16 kHz :. dB.
1 Price: £3,575.
to -disc transfer system. It is here that the program tape section: 40 Hz -16 kHz 1.5 dB.
, Control console SP272- mono /stereo
coming from the tape playback machine is processed, Channel separation : at least 35 dB. The control console SP272 contains one peak meter
metered and monitored. All important program Weighted signal-to- rumble ratio: at least 70 dB unit with one double light beam instrument M±W,
parameters such as disc level, equalisation pitch/ (measured according to DIN 45539). two peak level indicator amplifiers PTMV and one
depth control and automatic banding may be repro- Weighted peak flutter: 0.03
± "
max (measured power supply NS66; one VU meter unit with two VU
according to IEC, DIN 45507 and ANSI S 4 3 1971) meters (Weston), one correlation coefficient meter
ducibly influenced here. Tapes of greatly varying
Programme dependent automatic low -pass (30 U79t with instrument and two amplifiers VU70; one
level and quality parameters can be brought into
line to produce optimum results. The VMS 70 lathe kHz to 7 kHz): HK66 automatic high frequency cassette field with two active level controls RV72,
may be remote controlled from the program limiters (two off). four equaliser amplifiers PEVb, two two -channel
controller. Compatible cutting through reduction of vertical high -low -pass filters HT66 and one stereo monitor
Complement: signal: switchable 150/300 Hz, 6 dB /oct: EE70 com- oscilloscope; one automatic spiralling device KS70
Metering and indicating unit comprising dual light patilising cards (two off). (the light barrier LS70 is to be mounted on the
beam peak indicator, two VU meters and stereo Reduction in second harmonic (tracing distor- 'Magnetophon' M15 in MT72), one stereo flat -track
correlation meter and phase monitor scope. tion): TS66tracing simulator at least 18 dB at groove fader; one switchfield with one test oscillator PG70;
Relative disc level attenuator for selection of the excursion limit. one amplifier unit with six amplifiers PV26b, two
recorded disc velocity without influence on meter Automatic pitch /depth control information: every elliptical equalisers EE70; one power supply unit
indication (automatic range switching). # turntable revolution. NESP with three power supplies NS66, orte power
Preview offset control :for changing control channels Nominal line level: 0 VU corresponding to 4 supply 2TN15-01A and one impulse switch 1G.
separately from modulation channels to influence dbm. Price: £8,600.
record fill- factor. Both above are 0.5 dB /step ampli- Switchable for under modulated tapes: to -10 One stereo cutterhead SX68.
fier /attenuators. VU corresponding to -6 dBm in 0.5 dB steps. Price: £2,440.
Four active equalisers: for low /high /mid range Switchable for high output tapes: to *10 VU cor- One set interconnecting cables.
boost and droop control. responding to 14 dBm in 0.5 dB steps.
! Price: £56.
Tape playback equalisation: NAB /CCIR switch - Ten *Cutting sapphires 74 kMH at £10.60.
Four high /low cut -off filters for limiting of frequency
band width. able. Price: £106.
Two elliptical equalisers for reduction of low fre- Nominal disc level (peak recorded velocity): set- Two treble limiters HK 66 at £272.
quency vertical component to provide compatibility table in 1 dB steps between -4 dB and t8 dB: pro- Price: £544. 58
improvement. ducing 5 cm /s per channel corresponding to 7 cm /s
Linear board -fade attenuator. lateral at 1 kHz.
Output for tape recorder for simultaneous tape copy. Preview offset: -6 dB switchable in 0.5 dB and
1 dB steps.
Five-frequency precision test oscillator with push-
button injection into programme circuits. Programme equalisation, high /low equalisation:
Complete jack field (tip /ring /sleeve) provides access 60 or 100 Hz and 10 kHz: L 15 dB reproducible in 11
to all essential circuits for rapid fault diagnosis, steps.
insertion of external components etc. Presence /absence: 0.7, 1, 1.4, 2, 2.8, 4, 5.6 kHz
P8 dB reproducible in nine steps.
Monitor selector buttons give access to all vital
points for both metering and listening. High /low cut off filters: 60, 125, 250, 500 Hz, 8, 10,
Flashing push buttons as reminders of certain vital 12,14 kHz; about 12 dB /oct
non -standard functions. Prevent false starts and Other equalisers available on request.
lacquer spoilage. Automatic banding unit: max eight spirals; relay
Automatic banding unit provides spirals, selection less.
counting and lead -out from optical sensor on tape Timing of spirals: 0.25, 0.5, 0.7, 1, 1.2, 1.5, 2 s (time
recorder. Relay -less. function).
Mounting space and signal and power connections
Metering section : two light beam peak indicators
( -70 to ±5 dB);
provided for two Dolby Model 360/361 and EMT-156
PDM compressor. Two ANSI standard VU meters; one stereo cor-
relation meter; one stereo monitor oscilloscope.
Push button controls provided for: phase reverse,
channel reverse, Dolby insertion, equaliser insertion,
Expansion of metering section : 14 dB for standard
mono /stereo, 150/300 Hz compatibility turn -over alignment records.
frequency, cutter on /off, 14 dB test record gain Power consumption (dimensions (wth x dpth x

increase, monitor mono control and A /Bcomparison.

Preview /playback tape console MT72
Tapes are played on the tape deck of the special
MT72 console, which is equipped with special idlers Right: Neumann turntable and microscope
STUDIO SOUND, APRIL 1973 57
 DISC CUTTING EQUIPMENT normally prevented by the rising impedance of the 30 Hz (0.65A,1 cm /s peak), 2nd harmonic 0.6 %;

cutter head. However, in this amplifier a four pole 3rd harmonic 0.5 %; higher harmonic 0.1 %.
impedance matching network is inserted between Difference tones:
One helium reduction valve. the output stage and the cutting head. This network 6.6 kHz +7 kHz (0.4A, 8 cm /s peak), 400 Hz = 0.07%
Price: £20. converts the complex impedance at the output into 12.2 kHz +12.6 kHz (0.32A, 2.8 cm /s peak) 400 Hz
One helium cooling system BA4. a real load, essentially resistive, throughout the 0.1 %.
Price: £60. entire audible frequency range. Dimensions: plug in unit for 480 mm frame inser-
One Buchmann -Meyer light ZA21. Since the feedback is a motional feedback sampled tion (four height units).
Price: £98. in the moving parts of the cutter, it reduces non - Frontplate: 438 x 177 mm, cabinet depth: 337 mm.
One Strobotron ZÁ42. linearity in the cutting action at lower frequencies, Weight: 8 kg.
Price: £58. while throughout the operating range, it reduces Delivery: ready for rack mounting, frame included.
One microscope for stylus adjustment ZA12/68. system distortion and damps the cutter. In the GP701 By special order mounted in steel casing: 505 x 195
Price: £114. amplifier the entire frequency range is covered by x 400 mm.
Total price: £27,201 the feedback loop. In the low region at 40 Hz, for Price: G0701 two channel cutting amplifier, com-
Tape replay machine example, a feedback ratio of 12 dB is typical. plete with GE701 dual power supply: £3,880.
Either Telefunken M15 special complete in console. When the temperature of the cutter coil exceeds a Four channel cutter
Price: £4,000. preset value, the programme is electronically The Ortofon cutter head DSS661 and the drive
or Studer A80/VU- pre -listening. switched off and the head is disconnected. Average amplifier have been on the market for some years.
Price: £2,140. temperature is displayed on a front plate meter The cutter head has now been modified to cut four
cutting rubies are available as alternatives to sap- additional to the conventional cutter current meter. channel records, the carrier wave system, at half
phires at £12.00 each. The equalisation in the monitor section is adjusted speed. A head for regular speed recording is in
according to IEC /98 playback response. preparation.
The pickup playback preamplifier allows the use of LPS 691 four channel equaliser
either dynamic or magnetic pickups. Ortofon also produce a four channel equaliser,
All switching in the amplifier is made electronically LPS 691, equipped with logic circuitry for manoeuv-
with analogue switches. The only relay in the ampli- ring of the master tape machine and the monitoring
ORTOFON fier is the cutter connecting relay which is of the circuitry. The normal version is designed for two
Ortofon, 5 Trommesalen, DK 1614, Copen- mercury wetted contact type. programme channels plus two preview channels. A
hagen V, Denmark. The amplifier is provided with push buttons for special version for regular programme channels Is
Tel : (01) 31 08 83. manual switching cutter on /off and monitor feed- however also available.
back /pickup. Price: £1,095.
Agents: Feldon Audio Ltd, 126 Great Port- The power supply GE701 contains two identical New filter
land Street, London W1N SPH. supply systems. They supply each amplifier with A regulated low pass filter of a new design will be
Tel : 01 -580 4314. two symmetrical voltages referred to zero. available from the spring of 1973. The filter is design-
DSS 661 cutter head. ed for protection against the cutting of non- track-
Principle Technical specification able treble signals as well as against overheating of
Each moving coil system is connected to a separate Power supply GE701 the cutter head. Its operation is based on pulse
recording amplifier, the moving coil system being Mains supply: ac 50 to 60 Hz, 220V or 110V, +10 %. width modulated mos -fet's in an active filter
part of the negative feedback loop. So the two Output voltage per system (idle run): +40V, configuration.
channels are electrically isolated from each other. 0-40V.
The two moving coil systems in the cutter head are Maximum continuous supply current per system:
mechanically coupled to a common stylus holder In approx. 6A.
such a way that one moving coil system will move Dimensions: plug -in unit for 480 mm frame inser-
the stylus tip in a direction of 45° to the vertical and tion (three height units). WESTREX
the other moves the stylus tip in a direction per- Frontplate: 438 x 132.5 mm, cabinet depth: 337 mm. Westrex Company Ltd, 152 Coles Green
pendicular thereto ( -45 °). Weight: 20 kg. Road, London NW2 7HE.
This coupling arrangement, for which Ortofon Delivery: ready for rack -mounting frame included. Tel : 01 -452 5401.
has taken out a patent, allows the two moving coil By special order mounted in steel casing: 505 x 155
systems to drive the cutting stylus in the respective x 400mm.
3D11 Stereodisc recorder
directions without mutually affecting each other. Cutting amplifier G0701 Dynamic, negative feedback stabilised stereophonic
Negative feedback reduces distortion and damps Programme input arrangement and impedance: recorder compatible with all Westrex stereo disc
the cutter, resulting in low crosstalk, flat frequency balanced, floating 5k ohms. Feedback input arrange- systems. Makers say 'it retains the original advan-
response and wide frequency range. ment and impedance (at 1 kHz): unbalanced, approx- tages of a quick- change positive self -aligning stylus
Features imately 10k ohms. holder with large diameter stylus, low spurious
resonances and high sensitivity, and special high
The DSS 661 has a new shape which allows a work- Pickup input arrangement: 1 to 3 ohms dyn.
ing position with a tilt of 30° maximum to the vertical. temperature coil wire and insulation with quick
pickups balanced or unbalanced.
Due to the so called 'spring -back' effect it is neces- 1 to 3 k ohms magn. pickups, unbalanced.
change stylus heater wire clips ...
[It has] greater
sary to tiltthe cutterhead about 25° in order to obtain mid and high frequency sensitivity, higher recording
Drive coil output arrangement, assumed coil
an effective 'vertical' angle of 15° in the groove. In level capability and a new stylus mounting holder.
impedance: symmetrical to zero, 9 ohms.
accordance with another Ortofon patent the DSS 661 Monitor output arrangement, recommended load: 'Cooling is not required to consistently record very
has been prepared for gas cooling to reduce the balanced,floating: 1 to 10 k ohms. high levels without fear of distortion or recorder
temperature rise of the driving coils at heavy loads. Programme input sensitivity: (presettable) -6 damage. Long term stability is assured with the use
This Is particularly important when cutting frequency dBm, 0 dBm, +6 dBm. of 29 dB of negative feedback. Negative feedback is
adjusted for an ample margin of safety from the
test records and so on where a high driving current Feedback input sensitivity: approx 6 mV /cm /s.
must be applied for a considerable time Interval. Pickup input sensitivity: (1 kHz): Dyn. approx tendency to self- resonate. Negative feedback moni-
The gas- cooling protects the driving coils from 20p.V /cm /s. Magn. approx 0.6 mV /cm /s.
toring over the entire frequency range provides a
damage due to overheating. It is not necessary to Monitor output level (adjustable): programme metered and audible confirmation of performance'.
employ gas-cooling when cutting normal music input level.
records, but if the facility is at hand, it may as well be Maximum monitor output level (into approx Technical specification
used in all cases; it will never hurt and It may save 1k ohms) approx: +20 dBm. Type: 45 ° -45° stereodisc.
the cutter head from damage due to errors or Power available at all frequencies direct from Damping : stabilised negative feedback (29 dB at
accidents. The cooling gas must be either hydrogen power unit into external ohmic resistor (using +40V resonance).
or helium. as supply voltage): 500W, Coils: two drive, two feedback, one each per coil
Price: Stereo cutter head: £1,600. Cutting sapphire, Output connected to cutting head (DSS661): form.
'superior quality': £11.70. Cutting sapphire, 'first Available power raising with frequency to 500W at Drive coil impedance: 10 ohms nominal.
quality': £8.75. 20 kHz. Recording frequency range: 30 Hz to 20 kHz.
G0701/GE701 stereo cutting amplifier set Peak output current: 16 kHz, approximately 8A. Feedback voltage: 27 dBm (.035V) at resonance
The Ortofon cutting amplifier, G0701, has been Peak output voltage: 16 kHz, approximately 150V. (approximately 1 kHz) at 3.5 cm /s recording velocity.
designed with careful consideration for high power Corresponding to cutting velocity peak: 30 cm /s. Crosstalk: approximately 35 dB, 50 Hz to 10 kHz.
output and minimum intermodulation distortion and Typical data with DSS661. Measured on moni- Stylus: P98438 red sapphire, self -aligning.
harmonic distortion. The amplifier is constructed tor output terminal: Stylus heater wire: quick-change, spring -loaded,
for a sine wave output of 500W (peak power of 1 kW) Frequency response: +1 dB 20 Hz to 18 kHz. wire clip terminals.
which makes It possible to cut peak velocities of Harmonic distortion: Vertical stabilisation : advance ball.
more than 30 cm /s even at 20 kHz. The transfer of 1 kHz (0.4A, 25 cm /s peak), 2nd harmonic 0.4 %; Weight: 2.5 kg.
such high power, particularly In the treble region Is 3rd harmonic 0.2%; higher harmonic 0.05 %. Dimensions: 8.3 x 10.8 x 24 cm.
58
 The Series 2000 disc- cutting lathe is
designed to cut stereo records with
outstanding quality. (An identical Series 1000
lathe is also available for cutting records
in Mono)

MSR2000. All MSR Series 2000 lathes are fitted with

a 16 inch turntable, with a direct driven
DC motor, independent of mains frequency
and servo controlled for maximum speed

disc.cuttïng stability
'Varigroove' is provided on all MSR
Series 2000 lathes. This is controlled from

he an advanced head on the tape replay

machine
The MSR Series 2000 lathe is equipped with
stylus heating and swarf collection systems
and is built into a high quality
floor standing console

seeing is MSR Electronics Limited

believing.
MEETING HOUSE LANE . BALSALL COMMON
WARWICKSHIRE . ENGLAND
Telephone (0676) 32468

"D.S\\
Des'gn Engineers to the Recording Industry

IraserPeacoek
Associates ltd
are the tape and
BIAS ELECTRONICS cassette
B,E.1000 PROFESSIONAL RECORDER
*Wow and Flutter RMS Total 38 Cm /Sec 0.06;
*Frequency Response Overall
±2 dB.
*Noise Overall
-60dB
unweighted below
38 Cm /Sec 40 Hz to

32 mM
18 kHz

/mm Full Track copying people

*Separate Sensitivity EQ and Bias Adjustment for each speed
*Plug in Electronics *Plug in Head Block. We specialize in small and large
*Precision Cast Tape Deck *Electronic Tape Tension.
Illustrated: STEREO TRANSPORTABLE £534.00 runs,write today for a rate card
BIAS ELECTRONICS LTD
Unit Coombe Trading Est.,
8, Distributor to Studios Fraser. Peacock Associates Limited
Coombe Lane,
112-120 of KEITH MONKS AUDIO 94 High Street Wimbledon Village London SW19
London SW20 01 -947 3121 Microphone Stands, Etc. fpa 01.947 2233 sole UK distributors of Infonics

STUDIO SOUND, APRIL 1973 59

 AEG TELEFUNKEN preparation of master tapes: 152/76 cm /s.
AEG Telefunken, AEG House, Chichester Frequency response -playback:
Rents, Chancery Lane, London WC2. In preparing master tapes, 30 Hz to 15 kHz t3 dE.
Tel : 01 -242 9944. In duplicating musicassette tapes: 30 Hz to
10 kHz 3 dB.
M1528 tape duplicator In duplicating stereo eight tapes: 30 Hz to 15 kHz
1. A master console including:
3 aB.
Two professional -type M15 tape reproducers Frequency response- recording:
modified for tape speeds of 304/152 cm /s. One In preparing master tapes: 30 Hz to 15 kHz ±3 dB.
program panel subdivided into a crossbar distri-
In duplicating musicassette tapes: 30 Hz to 10 kHz
butor, eight attenuators of L12 dB, eight push-
button controls for automatic operations and one
i3 dB.
In duplicating stereo eight tapes: 30 Hz to 15 kHz
switch for the choice of either the musicassette or 3dB.
sterec -eight cartridge system. Four or eight VU All frequency response figures have been measured
meters for measuring program levels on each with DIN reference tape 45513.
channel can be furnished on request. Eight V797
plug -in replay amplifiers with their respective
Signal to noise ratio: with reference to a one to
one duplicating speed, signal to noise ratio loss is
interchangeable plug -in adjustment boards (eight
no greater than 1 to 1.5 dB.
boards for the musicassette system, eight for the
stereo -8 system and four for the preparing of master
Distortion: with reference to a one to one dupli-
cating speed, the distortion factor does not increase
tapes). Eight V696 recording amplifiers with their
(the percentage of distortion depends on the type of
respective E696 basic equaliser. One logical modu-
tape and on the level of signal used).
lar device for the automatic control of the duplicator.
Crosstalk at kHz: between the two tracks of the
1
One power pack.
master tape reproducer: greater than or equal to
2. Slave consoles, each of which contains:
50 dB. Between tracks one and two of musicassette
Three professional M28 tape recorders adapted to
tapes: greater than or equal to 28 dB. Between
76/38 cm /s speeds and to 3.81 mm tape. Inter-
tracks two and three of musicassette tapes: greater
changeable plug -in AE 696 adjustment boards
than or equal to 50 dB. Between adjacent tracks of
(three boards for the musicassette system, six for
tapes or stereo eight cartridges: greater than or
the stereo eight system, one for preparing master
equal to 50 dB.
tapes.) The first slave console contains the central
Mains voltage: 220V, 50 Hz (60 Hz on request).
oscillator, the separator amplifiers, and the power
amplifiers for the premagnetisation of the relative Current consumption:
slave recorders, while the other slaves contain only Master console: 2.8A
the power amplifier. A master console can drive up
for each slave recorder: 1.4A.
to four slave consoles for a total of 12 slave recorders
Production: (the number of musicassettes or
stereo eight cartridges depends, of course, on the

Survey: Technical specification

Master tape reproducer M15
Speed of master reproducer: 304 /152 cm /s.
length of the programs). For example, musicassette
with two programs lasting 20 minutes each: about
50 pieces an hour for each slave recorder.
The V797 playback amplifier:
Wow and flutter: approx 0.6'',.
Starting time: approx. 0.8s. Frequency range (depending on the multiplication

duplicátiñe Slave tape recorders M28

Speed of slave recorders: 76/38 cm /s.
Wow and flutter: approx 0.8
factor of the speed): 120 Hz to 260 kHz.
Input: balanced, floating.
Input impedance: suitable for connexion to replay

systemg
3 Starting time: 1s.
Speed of first slave recorder if set up for the
heads for high speed.
Output: unbalanced.
Output level: 1.55V ( +6 dBm) across 200 ohms.
Maximum output level: 5.5V ( +17 dBm).
Output impedance: 40 ohms.
Sensitivity : with a signal on 320 nWb /m tape
Ampex AD -15 running at 19 cm /s, the output level can be increased
up to 3V (12 ,-dBm).
Possible playback equalisations (by substituting
plug -in adjustment boards): 38 DIN or NAB x 8,
38 DIN or NAB x 4, 19 DIN S or H x 16, 19 DIN S or
H s 8, 9.5 DIN or NAB s 16.
Signal to noise ratio with adjustment in position
for an output level of +6 dBm and with DIN 19H
equalisation: unweighted at least 42 dB, weighted
(1) at least 56 dB.
It should be pointed out here that when the dupli-
cated tape is played back at its nominal speed
(4.75 cm /s for musicassettes and 9.5 cm /s for
stereo eight) the effective noise voltage is practically
reduced to the square root of the ratio one gets
between the duplicating speed and the nominal
playback speed mentioned above.
Distortion: Load resistance 300 ohms output level
+6 dBm: THD 0.07 per cent max. Output level +12
dBm: THD 0.05 per cent max.
Supply voltage: 20V dc.
Current consumption : 30 mA.
Attenuation of 50 Hz frequency: at least 80 dB.
Dimensions: double plug -in printed circuit 100 x
160 mm. Total depth with plug: 160 mm.
(1) The weighted noise is measured through a
filter with the same curve as the filter indicated in
the DIN 45405 standard (psophometric filter), the
single frequencies of which, however, are multiplied
16 times (e.g. 1 kHz x 16 =16 kHz).
The E696 Basic amplifier- equaliser
Frequency range (depending on the multiplication
factor of the speed): 120 Hz to 260 kHz.
Inputs: two unbalanced, electronically switchable
inputs.
Input impedance: at least 2 k ohms. Supply voltage: 20V dc. formats. Each slave can be equipped with a tailoring
Output: one, unbalanced. Current consumption : 1.8A. device to deliver a completed product. All transports
Output impedance: at most 20 ohms. Dimensions: 160 x 100 x 167 mm (including plugs). accept reels as small as 13 cm and reels or pancakes
Output load: at least 2 k ohms. Weight: Master console: approx. 290 kg. Each as large as 38 cm. Each master drives up to three
Output level: 0.5V at 16 kHz. slave console: approx 195 kg. slaves, with three slaves, a system produces 168
Maximum output level: 2V at 16 kHz. Dimensions: master console: 1.78m wide, 0.925m 365m copies in one eight hour shift. An internal
Equalisation: Input one (corresponding to 16 times high, 0.610m deep. Each slave console: 1.78 x reference oscillator protects tape speed from line
speed): low frequencies: fixed (according to stan- 0.925 x 0.61m (whd). power shifts.
dard characteristic corresponding to 1590 us at Prices: available on application. Features:
nominal speed). High frequencies: may be regu- The through the reel timing accuracy for any dupli-
lated from 5 dB to 20 dB at 240 kHz corresponding cator is x:0.08 per cent. Copies all major 3.8 mm and
to 15 kHz at nominal speed. Input two (correspond- 6.25 mm formats. Automatic system stop /master
ing to eight times nominal speed): low frequencies: rewind. Accepts reels or pancakes from 13 to 38
fixed (according to standard characteristic corres- cm diameter. Cassette /cartridge tailoring available.
ponding to 3180 us at nominal speed). High frequen- Servo -controlled tape tension. Internal reference
cies: may be regulated from +4 to +30 dB at 120
AMPEX oscillator for accurate tape speed. One master
kHz corresponding to 15 kHz at nominal speed.
Ampex (GB) Ltd, Acre Road, Reading drives up to three slaves. Attractive console design;
RG1 6HZ. convenient control bridge.
Equalisation at low frequencies can be fitted by
means of bridges on the connecting plugs. Tel: 0734 84411.
Amplification: max 6 dB to 16 kHz and respec- CD200 automatic cassette copier Technical specification
tively to 8 kHz. A high speed automatic tabletop copier. Vacuum Crosstalk rejection : 50 dB or better except between
Distortion: load resistance 2 k ohms output level columns completely isolate tape from the cassette stereo pairs.
(nominal): THD 0.07 per cent max. Maximum output mechanism. Professional duplicator heads are Bias oscillator: nominal bias frequency: 500 kHz.
level: THD 0.4 per cent max. used. The CD200 can turn out 375 C30 cassette Wow and flutter: 76 cm /s: 0.05 38 cm /s: 0.07`,'0,
Signal to noise ratio with 16 x set -up: unweighted copies per hour; a loader option makes it fully 19 cm /s: 0.1 ",,.
at least 60 dB weighted at least 76 dB (1). automatic. CD200 also rewinds cassettes to the Signal -to -noise ratio : will not introduce more than
With 8 x set -up: unweighted at least 62 dB, weighted start before copying, and senses and ejects defec- 3 dB noise on duplicate.
at least 76 dB (1). tive cassettes. Two -track mono and four -track Direct record input: 50 ohms unbalanced, accepts
Supply voltage: 20V dc. stereo /two -track mono versions available. Features: line level from 0.3V rms for recommended operating
Current consumption: 16 mA. Copies 375 C30, 225 C60 or 120 C120 cassettes per level.
Dimensions: 160 x 100 x 167 mm (including plugs). hour. Automatic loader option holds 100 cassettes; Fast speed: fast speed for rewind or search func-
The V696 recording amplifier can be loaded in 7s. Duplicates all tracks at one pass. tions manually adjustable. Approximately three
Frequency range: 90 Hz to 540 kHz. Automatically rewinds to start before copying; minutes for 1,520m, 36 cm reel.
Input: one, unbalanced. senses defective cassettes and ejects them sepa- Start time: 3s to normal flutter specifications.
Input impedance: at least 4k ohms. rately. One master controls up to five slaves. Stop time : 38 cm /s at 38 cm reel tape moves 76 mm.
Input level: 0.5V. Tape speed accuracy: within +,0.08 _+ from "
Input sensitivity : 02V. Technical specification beginning to end of reel. With internal bridge
(1) the weighted noise is measured through a filter Tape speed: 190 ('_0.2%) cm /s throughout length oscillator, tape speed unaffected by line voltage or
with the same curve as the filter indicated in the DIN of C60 cassette. frequency fluctuations.
45405 standard (psophometric filter), the single Rewind speed: internally adjustable from 254 to Power requirements: 105 to 125V ac, 50 to 60 Hz.
frequencies of which, however, are multiplied 16 i60 cm /s (factory set at 380 cm/s). Controls: system control selects number of slaves
times (e g 1,000 Hz x 16= 16,000 Hz). Start time: with 76 cm of unrecorded tape: 0.4s at to be controlled. By main 'start' and 'stop' buttons.
Output: one, unbalanced. 190 cm/s from true end of tape to beginning of Local control overrides system control and does not
Output impedance: 12 ohms maximum. program. 16s at 4.75 cm /s from true end of tape affect other transports.
Output load: at least 200 ohms. (start time-time to reach 90 ",, of spec speed). Tape formats:
Nominal output level corresponding to maximum Overall cycletime : at C30 cassettes, approximately Full and two track mono, full and two track stereo,
recording level: 4V. 40s plus load time (75 per hour per slave) C60 quarter track stereo, four track stereo cartridge,
Maximum output level: 10V. cassettes, approximately 75s plus load time (45 per eight track stereo cartridge: 6.25 mm tape 25
Distortion: with 200 ohms load resistance, with 4V hour per slave). or 38 um.
output level: THD 0.09 per cent max., with 10V Tape tension: constant at 93.3 (±15)g. Four track stereo cassette, two track mono
output level: THD 0.9 per cent max. Frequency response: (referenced to 4.75 cm /s cassette, 3,800 um tape. 12.7 um base. Tensilised
Signal to noise ratio: unweighted: at least 72 dB, playback speed). polyester.
weighted: at least 94 dB. System: 30 Hz to 12 kHz, =2 dB. Number of slaves: one to three slaves can be
Adjustment: level. Typical copy: 50 Hz to 8 kHz, 1-2 dB, using Ampex attached to a master reproducer.
Supply voltage: 40V dc. 361 cassette, biased for maximum long wavelength Reel size: 13 cm to 38 cm reel diameter. NAB or
Current consumption : 45 mA. sensitivity. EIA Std.
Dimensions: 160 x 100 x 167 mm (including plugs). Flutter: less than 0.05" rms NAB weighted. Tape speeds: 19, 38 and 76 cm /s.
(1) The weighted noise is measured through a filter Overall signal -to -noise ratio: 3 dB maximum Frequency response (1 :1 duplication):
with the same curve as the filter indicated in the degradation in 30 Hz to 10 kHz band. Master tape 19 cm /s NAB, Copies 19 cm /s NAB.
DIN 45405 standard (psophometric filter), the Crosstalk rejection: 20 dB (min) at kHz playback
1 Master speed 76 cm /s, Slave speed 76 cm /s:
between adjacent tracks of stereo pair. 50 dB (min) +2 to 4 dB, 50 Hz to 15 kHz.
single frequencies of which, however, are multiplied
16 times (e.g. 1,000 Hz x 16 16,000 Hz). between programs. Master tape 9.5 cm /s NAB, Copies 9.5 cm /s NAB,
The OS 696 Bias Oscillator Power: 105 to 125V ac 58 to 62 Hz 6A (48 to 52 Hz Master speed: 38 cm /s, Slave speed: 38 cm /s:
Nominal frequency : 560 kHz. operation optional). +2 to 4 dB 50 Hz to 12 kHz.
Output: balanced, floating. Operating temperatures: 10 °C to 35`C (-40 C to Master tape: 9.5 cm /s NAB, Copies 9.5 cm /s NAB,
Output level : 6V. 65 C storage). Master speed 76 cm /s, Slave speed 76 cm/s:
Distortion : 0.06 per cent max. Humidity: 5"ó to 95°;; non -condensing. 2 to 4 dB 50 Hz to 7.5 kHz.
Supply voltage: 20V dc. Weight: 16 kg. Master Tape cassette, Copies cassette, Master
Current consumption: 125 mA. Dimensions: 560 x 533 x 273 mm (wdh). speed 19 cm /s, Slave speed 19 cm /s: -2 to 4 dB
Dimensions: 160 x 100 x 167 mm (including plugs). Format tailoring : 76 cm of unrecorded tape 50 Hz to 10 kHz.
The HF 696 bias separator amplifier (including leader). Program 76 cm of unrecorded Master Tape cassette, Copies cassette, Master
Input: balanced, floating. tape at end (including leader). speed 38 cm /s, Slave speed 38 cm /s: -2 to 4 dB
Track formats: four -track stereo two -track mono. 50 Hz to 5 kHz.
Amplification: 3 dB.
Distortion: 0.08 per cent max. End of tape sensing : true end of tape sensed (2:1 duplication)
Outputs: two balanced, floating. independent of leaders, splices, sensing tape, or Master tape 19 cm /s NAB, Copies 9.5 cm /s NAB.
Supply voltage: 20V dc. tones. Master speed 76 cm /s, Slave speed 38 cm /s:
Current consumption: 1.1 A. Automatic slave loading: 100 cassettes (may be +2 to 4 dB 50 Hz to 12 kHz.
replenished manually while CD200 is operating). (4:1 duplication)
Dimensions: 160 x 100 x 167 mm (including plugs).
The LHF 696 bias power amplifier Load time: approximately 72. Master tape 19 cm /s NAB, Copies cassette,
Input: balanced, floating. Price: Available on application. Master speed 76 cm /s, Slave speed 19 cm /s:
Amplification: approx. 6 dB. +2 to 4 dB 50 Hz to 10 kHz.
Outputs: two balanced outputs, floating. AD15 duplicator system Direct recording from auxiliary source (up to
Output level: 15V. The AD15 offers a wide range of formats. Additional three copies per run) Recording speed: 19 cm /s
heads and guides permit changes from reel -to -reel NAB equalisation 6.25 mm tape: +2 to 4 dB
Distortion: 0.2 per cent max.
Admissible load: at least 40 ohms. formats to eight track cartridge formats to cassette 50 Hzto15kHz. 62,
STUDIO SOUND, APRIL 1973 61
 TAPE DUPLICATORS 19 cm/s open reel: 50 Hz to 15 kHz, ±2 dB. original recording. Provisions in the master assem-
System noise: bly allow increasing the number of slaves to twenty
. ystem set up for to cm's master at 3u4 cm /s dU by adding bias amplifiers.
3.8mmtape: +2 to4dB50Hzto 10 kHz. below blank, biased Ampex 404 series tape ASA The transport is equipped with its own loading/
Price: available on application. 'A' weighted at least 10 dB. unloading motor assembly to transfer tape directly
2.1 kHz bandwidth, 16 kHz (1 kHz at real speed) at from a reel to the storage bin. A photocell assembly
RR200 duplicator system least 5 dB. mounted in the tape path automatically counts the
The system consists of an RR200 master repro- 2.1 Hz bandwidth, 64 kHz (4 kHz at real speed) at number of master passes and injects a 120 Hz or
ducer and up to ten 3400 slaves. The RR2008 plays least 12 dB. 320 Hz tone on the opies for cutting points.
back eight- track, 25 mm masters to produce high - 2.1 Hz bandwidth, 160 kHz (10 kHz et .eal speed) at A new head produces a higher output at mid-
quality track cartridge tapes. One version of the least 8 dB. frequencies and greater efficiency at high frequen-
RR2004 uses 12.5 mm masters to duplicate four Total harmonic distortion: cies. Preamplifiers are mounted on the head
track stereo or four channel stereo formats; a System exclusive of tape, 0.2% at operating level. assembly. This arrangement avoids rf interference.
change of plug -in head assemblies and turn -around Overload margin: reproducing amplifier: up to and redi.ces signal -to-noise ratio by reducing
tape guides, and it becomes a 6.25 mm machine in level control 20 dB above operating level, after level capacitive shunting of the head cables.
either two or four channel format, depending upon control 17 dB operating level.
the head assembly used. The RR200 can be con- Recording amplifier: 20 dB above operating level.
certed from 152/304 cm /s to 76/152 cm /s by a change Bias supply: 1 MHz, adjustable to 60V rms at
3400 series slave assembly
of capstan idlers (provided) and removal of acapstan 0.5A rms.
The 3400 series slave assemblies are newly adapted
sleeve. Five different plug -In head assemblies are Power requirements: 117V (±10% ac, single versions of the Ampex Model 3200 slave assemblies.
available for the 3400 slave, each with its own bias phase, 50 of 60 Hz; 4A approx.
The 3400 series slave transports have turn -around
and record level adjustments: tape tensioning Dimensions: RR2004 660 x 762 x 1550 mm, RR2008 guides with 3.8 and 6.25 mm guides for tape width
adjusts automatically with each head change. Uses 660 x 762 x 1550 mm (wdh) Metal cabinet with all
conversion. Automatic tape tension programming
6.25 mm and 3.8 mm. electronics mounted in overhead bridge. is also provided to reduce the possibility of tape
Price: available on application. stretch or breakage.
Technical specification Plug -in head assemblies for both four track cassette
Tape speeds: 152/304 cm /s selectable (changeable BLM200 duplicator system
and eight track cartridge systems are ferrite core
to 76/152 cm /s selectable). Automatic high speed duplication of multichannel
type and are equipped with their own individual bias
Master tape formats: cassette and cartridge tapes is now offered by the
and record level controls for each track. The con-
RR2008: eight tracks on 25 mm wide tape. Ampex BLM200 duplicator system. Rewinding. trols are on top of each head assembly, Insuring
RR2004: four tracks (staggered) on 12.5 mm wide stopping, and rethreading of the tape is eliminated
interchangeability without resetting controls. No
tape, four track (in line) on 12.5 mm wide tape. by use of an endless loop tape in the master trans-
wiring changes are required when changing from
RR2004: full track two track (in line) four track port. All solid -state electronics are used through-
four track cassette to eight track cartridge head
(staggered) or four track (in line) on 6.25 mm wide out, The system consists of the BLM200 Bin Loop
assemblies.
tape. Master and up to 20 slave units of the 3400 series.
The 3400 series slave head assemblies for all
Maximum reel size: Constructed on a building block principle to provide
standard open -reel formats are also available.
356 mm outside diameter: 6.25 mm and 12.5 mm for future expansion, the basic BLM200 mister will
tape. drive up to ten slaves and an optional configuration
266 mm outside diameter 25 mm tape. is offered to drive twenty slaves.
Wow and flutter: less than 1 % peak to peak from BLM masters are available In two models, the Technical specification
0.5 Hz to 10 kHz (unweighted). Will not introduce 8LM2008 and the 8LM2004. The BLM2008 is an eight - BLM200 Master assembly
more than 0.15% rms (ASA 'A' weighted) In copy. channel version for cartridge duplication. However, Tape speeds: 152/304 cm /s or 304/608 cm /s.
Electronics Bandwidth : exclusive of equalisers, the eight -channel BLM2008 system will also duplicate Master tape format: eight tracks on 25 mm wide
+1 dB 300 Hz to 300 kHz. four channel cassette tapes by rotating the slave tape 38 µm polyester. Recorded at 19 cm /s NAB
Equalisation switching : independent switching is tape guides and replacing the plug in slave head equalised.
provided for both master and copy equalisation. assembl ies. Maximum tape capacity: 380m (about 45 minutes
Frequency response of reproducer: The BLM2004 is a four channel version for cassette of playing time per program track at 19 cm /s).
19 cm /s NAB master, 304 cm /s, 800 Hz to 160 kHz, duplication. If a four channel cassette master unit is Wow and flutter: less than 1 % peak-to -peak from
±2 dB, (50 Hz to 10 kHz at 19 cm /s). purchased first, it can be field converted to an 0.5 Hz to 10 kHz (unweighted). Will not introduce
19 cm /s NAB master, 152 cm /s, 400 Hz to 120 kHz, eight-channel cartridge version by adding a bias more than 0.1 % rms (NAB weighted) in final copy.
±2 dB, (50 Hz to 15 kHz at 19 cm /s). amplifier, a power supply, and four more channels of Frequency response:
38 cm /s NAB master, 304 cm /s 400 Hz to 160 kHz, electronics. Conversion of the slave units is possible Reproduce chain from 19 cm /s NAB equalised
±2 dB, (50 Hz to 20 kHz at 38 cm /s). in the field because all 3400 series slave units are master: +1 dB 500 Hz to 160 kHz at 304 cm /s.
Typical frequency response of copies (tape already equipped with dual-width guides and use +1 dB 1 kHz to 320 kHz at 608 cm /s (30 Hz to 10 kHz
limited) plug -in head assemblies. Installing the eight -track at final copy speed).
4.75 cm/s cassette 50 Hz to 8 kHz +2 dB. head assemblies automatically programs the Duplicated copies: ±2 dB, 50 Hz to 10 kHz, 9.5
9.5 cm /s cartridge or open reel: 50 Hz to 10 kHz correct tape tension. cm /s eight track cartridge. +2 dB, 50 Hz to 8 kHz
+2 dB. Working master tapes for both formats are recorded at 4.75, cassette.
on wide tape with 38µm polyester backing, recorded Tailoring tone: switchable 120 Hz or 320 Hz,
at NAB equalisation. Recordings are made in four- actuated by photocell, applied at saturation level to
to- eight-track formats on eight -track recorders such input of record amplifiers.
as Ampex Model MM10008 or Model ÁG4408. A Crosstalk rejection : between the tracks or between
working master tape for the eight track duplicator the adjacent even or odd track pairs; greater than
system follows the same track configuration as that 50 dB from 30 Hz to 10 kHz (at final copy speed).
of the eight track cartridge format: tracks one and System noise: better than 10 dB below a blank,
five, tracks two and six etc as stereo pairs, all in biased, Ampex 404 series low noise tape; 30 Hz to
forward direction. For the four track duplicator 5 kHz at final copy speed. Better than 6 dB up to
system, tracks three and seven make up the stereo 10 kHz.
pair in the forward direction, and tracks six and two Total harmonic distortion: system, exclusive of
in the reverse direction. (When making the master tape; 0.3% at Ampex operating level.
tape, recording is done on tracks, three and seven Overload margin: up to reproduce level control
in both directions.) and record electronics: 20 dB above Ampex operat-
ing level. Reproduce electronics after the level
BLM200 Master reproducer control: 17 dB.
The BLM200 master reproducer is a s =1f- contained Environmental conditions: temperature: 16 to
bin -loop system. It consists of a bin -loop tape trans- 41 °C.
port, a reproduce head and preamplifier assembly, Relative humidity: 50 to 90 %.
reproduce amplifiers, record amplifiers and a bias Power requirements: 115V (+10 %) ac single
oscillator /amplifier. The BLM200 drives up to ten phase, 50 or 60 Hz: 7A (BLM2004) and 9A (BLM2008)
slaves assemblies at up to 32 times the speed of the at 115V.
Dimensions: 155 x 107 x 69 cm
Weight: 225 kg.
Price: available on application.

Left: Ampex BLM 200 duplicator 64

62
 highest attainable technical
performance

quick
and easy
No major repair facilities available?
This professional tape recording equipment needs none
and can be used with confidence anywhere in the world.
In the past a fault in sophisticated equipment could mean
expensive down time, but in the E200 any fault can be
quickly isolated and the part or circuit replaced.
All major mechanical components and sub -assemblies are
quickly and easily changed. Many circuits simply plug -in.

Contact Nick Nichols at our

London office, telephone
01 -874 9054

LEEVERS-RICH NEUMANN SX68

EQUIPMENT LIMITED F.W.O. Bauch Limited
A Member of the MCP Group 49 Theobald Street
Boreham Wood Herts.
LEEVERS -RICH EQUIPMENT LIMITED
319 TRINITY ROAD, WANDSWORTH,
Tel: 01-953 0091
LONDON SW18 ENGLAND

STUDIO SOUND, APRIL 1973 63

 TAPE DUPLICATORS Auxiliary cassette to cassette unit cassettes can be loaded and unloaded while others
If both 6.25 mm tape and cassettes are to be used as are still rewinding. Cassettes can wind forward or
masters, then a separate high speed cassette replay backward simply by reversing the cassette position.
3400series slave assembly unit may be plugged into the standard master The speedwinder has individual cassette shutoff at
Tape speed: 76/152 cm /s or 152/304 cm /s. Cassette rewind unit. the end of each tape so that cassettes of any length
Slave tape format: eight tracks on 6.25 mm tape Cassette to cassette copier can be wound simultaneously.
38 m or 25:1m polyester or acetate (Ampex 681 tape Up to four cassettes may be loaded independently Dimensions: 356 x 212 x 121 mm.
or equivalent). Four tracks on 3.8 mm wide tape, into the fast wind unit. Half- hour-per -side (C60) Weight: 5 kg.
12.5 ;a.m polyester (Ampex 9219 tape or equivalent). cassettes are rewound in approximately 20s and are Capacity : six cassettes.
Other formats available. ejected automatically at the end of the process. Power: model SWE 220V ac, 0.75A.
Maximum reel size: 36 cm in diameter. A hub Operation Warranty: one year.
diameter smallerthan 11.5 cm (NAB size) not recom- The machines demand little or no skill to operate Price: £100.
mended for 3.8mm wide tape. and with electro- mechanical interlocks, monitor
Wow and flutter: less than 1". peak-to -peak from speaker and indicator lamps their operation is
0.5 Hz to 10 kHz (unweighted).Will introduce less than simple and foolproof and unskilled personnel can Infonics reel to reel duplicator model RR4
0.1 rms (NAB weighted) in copy. be trained in a few minutes. (stereo)
Power requirements: 115V Head and track configurations Duplication of tapes recorded at any speed from
(zr_10 %) ac single
phase, 50 or 60 Hz 2A per slave ässembly. The standard master unit contains two record and 4.75 to 38 cm /s is performed at 63.5 cm /s, with all
Dimensions: 79 x 66 x 66 cm. two replay channels, and standard heads are tracks being duplicated simultaneously. The reel to
Weight: 68 kg with metal cabinet. supplied to transfer any two tracks simultaneously reel duplicator produces three 365m reels of mag-
Price: available on application. within the normal 6.25 mm tape and 'Philips' cassette netic tape from a master reel in ten minutes. Plug-in
standards. Extra channels and non -standard track slaves extend the duplicator's capacity by an addi-
configurations can be supplied to order. tional four duplicate tapes so that a system consist-
Durability ing of a duplicator and two slaves produces 11
B &A All tape heads in B & A systems equipment are tapes every ten minutes.
Branch and Appleby Ltd, 42 High Street, manufactured by Branch and Appleby Limited, and Duplicating time (30 minute tapes): four minutes.
Harrow -on- the -Hill, Middlesex. are fully guaranteed subject only to fair wear and Master duplicating speed: 63.5 cm /s.
tear, for six months. Frequency response remains Copy duplicating speed: 63.5 cm /s.
Tel: 01 -864 1577. constant throughout head life, which is not less Master recording speed: 4.75 to 38 cm /s.
The B & A Systems Division of Branch and Appleby than 1,000 hours for the reel -to -reel deck and not Frequency response: 20 Hz to 15 kHz, ±3 dB.
manufacture head electronics and high speed less than 2,000 hours for the cassette desks. Signal to noise ratio: 50 dB.
copying equipment for tape and cassettes. The In the event of mechanical or electronic failure: Wow and flutter: 0.2 % rms.
equipment is variably custom built to satisfy specific 1. the cassette decks (which are factory set for Timing accuracy: 0.2 %.
requirements and is designed around modular units. immediate use) unplug on the removal of the cover Dimensions: 406 x 406 x 420 mm.
Vaiiety of in cassette' dubbing machines has and one screw, Weight: 22.2 kg.
evolved during the past three years which can 2. the electronic circuit boards slide into edge Price: £1575.
satisfy most small to medium production require- connectors -no technical knowledge is required to
ments in the educational and entertainment fields. replace them.
A typical technical specification follows. Comple- 3. the above and all other parts are available by return Infonics reel to cassette duplicators (Super
mentary high speed rewind units and demagnetisers of post from B &A Systems on an exchange replace- RC-2 or Super RC-4, mono or stereo available).
are also offered. ment basis. The Super RC line of reel to cassette duplicators
Master reel to cassette copier Master Copier Technical specification features a 152/76 cm /s master tape transport with a
This unit uses a reel -to -reel playback deck to trans- Standard machine frequency response: 40 Hz to dual speed hysteresis- synchronous capstan motor
fer master recordings made at9.5 cm /s at a speed of 11 kHz rh2 dB. and two torque motors.
3.8 cm /s on to eight cassettes running at 19 cm /s for Cassette to cassette frequency response: Duplicating time (30 minute tapes): 2.3 minutes.
eventual playback at the standard speed of 4.75 50 Hz to 8 kHz f3 dB. Master duplicating speed: 152 or 76 cm /s.
cm /s. The master reel -to-reel deck and the cassette Signal to noise ratio : within 2 dB of master tape. Copy duplicating speed: 38 cm /s.
decks are all electronically interlocked during the Crosstalk rejection, standard model: better than Master recording speed: 19 or 9.5 cm /s.
dubbing process but the system allows the stopping 46 dB. Frequency response: 20 Hz to 10 kHz +3 dB.
or removal of any cassette during dubbing without Distortion: no degradation of master tape. Signal to noise ratio: 45 dB.
disturbing the remaining cassettes. The system Wow and flutter: less than 0.25% rms. Wow and flutter: 0.3% rms.
run -up time is less than 2s. Equalisation, standard model: to DIN 45513. Timing accuracy: 0.2 %.
Master cassette to cassette copier Level indicators: true peak reading meters. Dimensions: 572 x 610 x 380 mm.
This is similar to the master dubber, but with a high Bias supply: crystal controlled master oscillator, Weight: 4.1 kg.
speed cassette playback deck substituted for the push -pull power stages. Price:
reel -to-reel deck. Monitor speaker: switchable to either channel Super RC -2 £1743.
Slave copier volume adjustable. Super RC -4 £2415.
The eight cassette slave unit is connected to the Master deck rewind speed : 20 minutes tape in 35s.
master unit by a single multicore cable and is Auxiliary input: three pole GPO jack low impe-
remotely controlled via the mastercontrol panel. Any dance 1.5 k ohms for additional master deck. Infonics reel to reel duplicator model RR2
Duplicating rate without slave units: up to 60 type (mono)
number of slave units may be added to increase
C60 cassettes per hour. Duplication of tapes recorded at any speed from
output; for example with ten slave units over 5,000
Transfer speed: four times normal playing speed. 4.75 cm /s to 38 cm /s is performed at 63.5 cm /s with
dubbed cassettes can be produced in an eight hour
Power requirements: 210 to 250V 50 Hz 2A. all tracks being duplicated simultaneously. The reel
day.
Console dimensions: to reel duplicator produces three 365m reels of
floor standing 1,200 x 540 x (HWD).
570 mm magnetic tape from a master reel in ten minutes.
desk type: 580 x 540 x 570 mm (HWD). Plug-in slaves extend the duplicator's capacity by an
Weight: additional four duplicate tapes so that a system
floor standing: 37 kg. consisting of a duplicator and two slaves produces
11 tapes every ten minutes.
desk type: 33 kg.
Duplicating time (30 minute tapes): four minutes.
Master duplicating speed: 63.5 cm /s.
Copy duplicating speed: 63.5 cm /s.
Master recording speed : 4.75 to 38 cm /s.
INFONICS Frequency response: 20 Hz to 15 kHz, ±3 dB.
Agents: Fraser -Peacock Associates Ltd, 94 Signal to noise ratio: 50 dB.
High Street, Wimbledon Village, London Wow and flutter: 0.2% rms.
SW19. Timing accuracy: 0.2 %.
Tel : 01 -947 2233/1734. Dimensions: 406 x 406 x 420 mm.
Weight: 22.2 kg.
Infonics fast speedwinder Price: £1102.
The Infonics speedwinder will rewind or advance up
to six cassettes at high speed. Any combination of
Infonics cassette copier 102
The model 102 makes two cassette copies from an
original cassette at 63.5 cm /s or approximately 14
64
times the normal cassette playing speed. Two C30 Tape speed: 38 and 19 cm /s standard; 19 and 19 cm /s recommended. Loop bin system 304 cm /s.
cassette copies are produced every minute. Both 9.5 cm/s to order; 76 and 38 cm /s to order. Slave speed: 152 or 76 cm /s.
tracks are duplicated in one run. Cassettes of any Tape speed stability: better than +0.2%from end Capstan Drive: Flywheel and belt drive to hyster-
length can be run in the copier up to C90s. to end of reel with reference to absolute. esis synchronous motors. Slave capstans ceramic
Duplicating speed: 76 cm /s. Rewind speed: 730m in 90s continuously variable. coated for less wear and tape slippage problems.
Duplicating time: (C30s): minute. 1 Start time: 0.9s to rated wow and flutter condition. Wow and flutter: will not add more than 0.15".,
Rewind time (C30s): 30s. Spool capacity : 29 cm European, 26.7 cm NAB, duplicates measuring components to 400 Hz.
Frequency response: 40 Hz to 10 kHz +3 dB. 21 cm cine. Frequency response: 9.5 cm /s duplicates +2 dB,
Bias oscillator: 500 kHz. Wow and flutter: (measured over bandwidth of -3 dB 40 to 10 kHz 4.75 cm /s duplicates 4 2, -3 dB,
Dimensions: 445 x 305 x 260 mm. 200 Hz) 0.06° rms total at 76 cm /s, 0.06% rms total 40 to 10 kHz.
Weight: 15.9 kg. at 38 cm /s, 0.08% rms total at 19 cm /s, 0.1 rms Crosstalk rejection: greater than 50 dB except,
Price: £900 total at 9.5 cm /s. between cassette stereo pairs.
Frequency response: (overall response within +2 Master tape and reel sizes: 25 mm or 12.5 mm for
Infonics reel to cassette slave duplicators dB between) 40 Hz and 25 kHz at 76 cm /s, 40 Hz and eight channel. 12.5 or 6.25 min for four and two
(CS -2 and CS-4 mono or stereo available). 18 kHz at 38 cm/s, 40 Hz and 14 kHz at 19 cm /s, channel. Up 25 mm reel on master.
To expand the duplicating capacity of all Infonics 40 Hz and 10 kHz at 9.5 cm /s. Noise level: measured Slave tape and reel sizes: 6.25 mm and 3.8 mm
duplicators up to three cassette slaves (CS) may be unweighted at 38 cm /s. Full track 62 dB below peak cassette up to 36 cm reels on slaves.
electrically connected to the duplicator. Each slave level. Stereo 60 dB below peak level. Twin track Electronics: amplifiers and equalisers on plug -in
makes an additional eight cassettes in complete 58 dB below peak level. cards. All solid state.
synchronism with the master tape. Cross talk: Twintrack 45 dB minimum at 1 kHz. Heads: Ferrite for maximum head life and minimum
With a system consisting of one duplicator and one Distortion: total amplifier distortion at peak level maintenance on slaves. Heads on plugs for easy
slave, therefore a total of 12 C-30 cassettes can be 0.2% between 40 Hz and 15 kHz. change of duplication formats and maintenance
duplicated every 23 minutes. This provides a Input: -14 dB for peak recording level with preset Mumetal on master.
duplicating capacity of 1,400 cassettes every eight sensitivity adjustment. 10 k ohms bridging. Bias frequency : 1 MHz crystal controlled.
hours. Output: maximum output before clipping +22 dBm Tape guides: except in head assemblies are roller
Price: CS -2 £1575. CS -4 £2100. into 600 ohms. Source impedance approximately type for minimum tape stress.
50 ohms. Tape wipers: on all units built -in wipers to reduce
Metering : VU meter standard ppm to order. Swit- head clogging and wear.
ched to read 'line in' and 'line out' and'reccrd'. Production capabilities: Capacity based on pro-
Monitor: Switched to read 'line in' and 'line out'. gram content is about 32 minutes total all sides,
BRENELL Terminations: Cannon XLR3. production should be approximately 640 to 840 eight
Brenell Engineering Co Ltd, 231 235 Duplicating system price: from £1945. track cartridges per one slave during an eight hour
Liverpool Road, London N1. shift. About 320 to 420 cassettes per slave during an
Tel 607 8271.
:
eight hour shift. (This of course, depends on oper-
ator skill and down time of duplicator.)
Tape duplicating equipment made to customer's Programmed operation: manual slave start and
specifications. LIBERTY/UA stop at master cabinet or automatic start from
Agents: Avcom Systems Ltd, Newton master tape leader through photocell logic. Manual
Works, Stanlake Mews, London W12 7HA. stop at master or predetermined stop after desired
Tel: 01 749 2201. number of runs through predetermined counter in
master cabinet.
KLARK TEKNIK Liberty tape duplicator Power requirements:
Klark Teknik Ltd, MOS Industrial site, The Liberty tape duplicator is designed primarily to
Master 720W; per slave: 180W
Summerfield, Kidderminster, Worcester- mass reproduce cartridge and cassette tapes on a
120V. 60 Hz, (220V 50 Hz operation available).
shire. reel to reel basis, to be broken down after dupli-
Shipping weight: about 726 kg.
Tel 0562 64027. cation. This method of duplication provides a more
:
Prices: from £7920 (with 6.25 mm loop bin master
consistent and higher quality finished product than
Teknik 2000 tape transport transport, quarter track electronics for stereo
can be achieved within cartridge duplication.
A range of tape recorders and reproducers from cassettes and one 'slave' position). Note: This
The duplicator consists of one cabinet rack contain-
38 mm to 50 mm tape widths. equipment can be ordered for cassette or eight
ing the head preamps, slave driver electronics, bias
Type 2000S track cartridge use, with a number of slaves, and
supply, master tape deck and tape bin. The master
Slow speed, multi -track for cassette and cartridge with 25, 12.5 or 6.25 mm loop bin master options, and
unit will drive one to ten slaves.
quality control. a Mumetal or ferrite head option.
A special 6.25 mm tape loop bin system is available
Features: wow and flutter 0.6% at 9.5 cm /s; dc for cassette duplication where it is not desirable to
servo-controlled capstan; digital electronic tape go to 25 mm or 12.5 mm masters with accompanying
measurement; complete logic control; all solid added mastering expenses and equipment.
state relays; low s/n ratio 60 dB (weighted); can Necessary associated equipment would be a break-
operate with pancake spools to 43 cm diameter; down winder such as the Liberty Winder CW15
constant tension in all modes for storage of dupli- with 20 Hz sensing amplifier. PENTAGON
cated tape. Liberty Tape Duplicator LT1600 series Agents: Afcom Systems Ltd, Newton
Type 2000N -25 mm Duplicating ratio: 16:1. Works, Stanlake Mews, London W12 7HA.
Variable speed 19 cm /s-38 cm /s for preparing Master speed and system: real time of master is Tel: 01 749 2201.
masters. Available as reproducer only or as a
complete recorder. Pentagon make a number of units which can be
Features:less than 0.05ió wow and flutter; extremely combined in a variety of ways. Systems can be reel
high audio and mechanical performance. to reel, reel to cassette, cassette to cassette or
Available April-Cartridge /cassette winding cassette to reel; two track or four track; eight or 12
machines-comprehensive range of automatic times copying speed ratio; various speed and
high -speed logic controlled winders /splicers. Klark widths of tape. A few typical designs are described
Teknik specialise in complete installations including below.
interface mixers, and so on. RM1200 /RM1400 reel to reel, two or four track
master
Master tape deck:
Designed for high speed duplicating. Direct drive
capstan from dual speed synchronous motor. Two
LEE VERS -RICH direct drive inducation spooling motors. Failsafe
Leevers -Rich Equipment Ltd, 319 Trinity differential mechanical brake system. Interlock
Road, Wandsworth, London SW19. motion control circuitry employing relay and solid
Tel: 874 9054. state switching logic. Automatic tape lifter in fast
winding modes, defeatable for cueing purposes.
Systems built to customers specific requirements Master operating speeds: 76 cm /s and 152 cm /s
based on the E200 open reel tape duplicating master.
machine. Rewind time: approximately 45s for 18 cm reel.
Power: 115V, 60 Hz single phase.
E200
Tracks: full, twin and stereo dimensions to BS
66
1568 -1970.
STUDIO SOUND, APRIL 1973 65
 I TAPE DUPLICATORS and two direct drive spooling motors. Uses relay
operated push- buttons with defeatable automatic
tape lifter (for cueing purposes). Will accept NAB
capstan drive motors for greater speed accuracies.
Has precision capstan and slider assemblies and
channel selector switches for greater flexibility and
operated push- buttons with defeatable tape lifter hubs. Bias readout, individual channel selector reliability. These slave modules are designed for
(for cueing purposes). Cassette transports have switches. 'Accutrack Metering' and pull -out circuit use with the cassette copier series of duplicators
synchronous drive capstan motors. Both reel and cards. (C120- C140). A total of three additional slaves
cassette transports are designed for continuous modules (six slave positions) can be added to the
operation. Bias readout, individual channel selector C120 duplicator without additional electronics. A
CM -1400 Cassette Master (For 4.75 cm /s cassette total of two additional slave modules (four slaves)
switches. 'Accutrack metering' and pull out circuit masters)
boards. Will accept NAB hubs. can be added to a C140 duplicator unit without
Plug in module adaptable to Pentagon master additional electronics. The slaves are housed in
systems that do not already possess cassette solid walnut cabinets to complement the C120/C140
C1323 Tri -Master 'Editor' duplicator master capabilities. duplicator line. Additional electronics may be
Reel to cassette, cassette to cassette, cassette to purchased to increase system size.
reel (for 9.5 and 19 cm /s reel masters 4.75 cm /s
cassette masters). RS2410 Reel to reel slave (6.25 mm tape)
This system permits the duplication of either reel to Two speed 27 cm reel to reel slave transport for
reel or cassette masters on to three cassette slave reproduction of 6.25 mm reel copies of programmed CS -440 Four station cassette slave
positions. In addition, this system can convert the materials. The transport has two direct drive Four position slave module utilising synchronous
reel play transport into a record deck. Through use spooling motors. The capstan motor is a direct capstan drive motors for greater efficiency and
of the cassette master position, it is then possible drive dual speed heavy duty synchronous motor. accuracy. System design enables hook -up of
to transfer cassette program information on to the Transport is designed for continuous operation and unlimited number of slave modules to master
reel to reel transport for editing purposes. The reel is housed in walnut veneer cabinet. System will console due to slaves unique design. Cassette
to reel transport is a two speed 27 cm deck with accept 27 cm pancake reels with conventional transports are ruggedly designed for continuous use
relay operated push- buttons. The tape lifter can be NAB hubs. This reel slave can provide 38, 19 and application and have precision capstan and slider
released for cueing purposes. The tape deck uses 9.5 cm /s reel copies from 38, 19 and 9.5 cm /s reel assemblies. Also pullout circuit boards for service-
direct drive dual speed synchronous capstan motor masters. ability.
and two direct drive spooling motors. The cassette
transports have synchronous drive capstan motors. RS -1410 Reel to reel slave (38 µm tape)
Both reel and cassette transports are designed for 27 cm reel to reel slave transport with direct drive S-1400 Eight station cassette slave
continuous operation. Bias readout, channel spooling motors. Capstan motor is a direct drive Same as above CS 420 /CS 440 slave system specifi-
selectors test switch. 'Accutrack Metering' and pull heavy duty synchronous motor. cations except for number of slave positions. This
Transport is
out circuit boards. Will accept NAB hubs. ruggedly designed for continuous duty operation system contains eight slave positions in one module.
and is mounted in a functional walnut veneer Note: available in two or four track formats and in
C5400 Reel to cassette (for 12.5 mm, 9.5 and 19 cabinet. System will accept 27 cm pancake reel eight or 12 times copying speed.
cm /s reel masters) with standard NAB hubs. Slave provides 4.75 cm /s Price: master and twc slaves; either eight or 12
A stereo duplicator system that provides four cassette programs for loading into cassette shells. times copying speed ratio; for reel to reel, reel to
cassette copies from 12.5 mm reel tape masters. cassette, or reel to reel with a 6.25 cm master and
The tape transport will accept 27 cm reels and 38 um cassette tape open reel slaves, for subsequent
utilises a direct drive dual speed synchronous S -140 Two station cassette slave reel breakdown and cassette loading, sells for
capstan drive motor and two direct drive spooling Two position slave module utilising synchronous £2,100.
motors. The push buttons are relay operated and
the tape lifter is defeatable (for cueing purposes).
The cassette transports have synchronous drive
capstan motors. Both reel and cassette transports
are designed for heavy duty operation. All cassette PHILIPS
positions have individual audio /bias level controls reels. After rewinding it stops at the beginning,
Pye TVT Ltd, PO Box41, Coldhams Lane, ready for the next duplication run.
to permit precise and accurate level adjustments on Cambridge CBI 3JU.
all cassette record channels. Premium stereo (four
Head assembly
track) cassette heads are included in this system. Tel : 0223 45115. A plug -in head assembly is mounted on the tape
Bias read -out, individual channel selector switches, deck. The assembly is provided with two Ferroxcube
Philips STD playback heads for full -track mono and twin-track
'Accutrack Metering', mono /stereo switch and pull Philips STD tape duplicators consist of one master
out circuit boards are all standard on this duplicator. stereo use. In this way the system is suitable for
reproducer and any number of slave recorders, up both mono and stereo application. The changing
to twenty. The machines are solid -state and self - from one to the other is effected by simply turning a
C -340 Cassette to cassette (for 4.75 cm /s cassette contained which implies that a simple installation switch on the reproducer, re- plugging the connec-
masters) consisting of one master and two slaves can be tion cables underneath the slave tape decks, and
Duplicating system consisting of one cassette extended just by adding a number of slaves. The adding a few electronic units. If required, a head
master with three cassette slave positions. Unit equipment complies with the most severe demands assembly equipped with two half-track playback
includes features such as 'Accutrack Metering' bias of studio transcription services. heads can also be supplied. Exchanging of the head
read -out, individual channel selector switches, test Master Reproducer assemblies is easily effected because of the plug -in
position switch and pull out circuit boards. Trans- The master reproducer comprises a steel console, type fixation.
ports are driven by synchronous capstan drive containing a tape deck and three 480 mm panel units. Because of the high electrical resistance of the
motors. Each cassette position has precision cap- These units are: a container for the plug -in ampli- cores, Ferroxcube heads give only low electric
stan and slider assemblies. fiers, a filter unit, and a 24V dc power supply. losses. As a result the intrinsic head noise is very
Note: Models are available in both eight and 12 Tape deck low, which favourably influences the signal -to -noise
times normal play speeds and in two and four track The master reproducer is equipped with a heavy - ratio. In fact the cverall signal -to -noise ratio of the
formats. duty tape deck being specially adapted for tape copy tape is better than 60 dB, with the appropriate
duplicating. A hysteresis synchronous motor for setting of frequency response and bias. Moreover,
1500 and 3000 rpm gives tape speeds of 76 and 152
C -140 Cassette copier the low losses at high frequencies means that low
cm /s. The tape deck is provided with an automatic bias currents are required for recording. This is
This model offers a cassette master and cassette
tape lifter which comes into operation on rewinding. especially important for high -speed tape duplication
slave position. One push- button starts and com-
Tape tension is controlled electronically and kept where bias frequencies of 700 kHz are employed.
pletes each duplicating run. Uses integrated cir-
at 80g. Ferroxcube heads are highly wear resistant, as a
cuits has built in rewind capabilities for both master
and slave positions as well as channel selector
Controls result of which the electrical performance during
The tape deck of the master reproducer is provided total operation life is practically constant. Conse-
switches. Duplicating speed is 38 cm/s and has
with push- buttons for start, stop and fast rewind. quently electronic adjustments to compensate for
add -on capability of recording from reel masters.
These buttons also control the operation modes of the head wear effect are only necessary after long
the slave recorders. In addition, there is a con- intervals. The life of the heads is 5000 operation
RME -2410 Reel Master (For use with most Pentagon tinuous control to adjust the fast -winding speed.
slave models). Uses 9.5 and 19 cm /s reel masters.
hours on an average.
An end -stop switch employing a light- dependent
Two speed 27 cm reel to reel master transport resistor (LDR) unit automatically stops the master Overall specification
complete with control electronics. VU meters and reproducer if the tape should break, or when the end Frequency response (with optimum bias adjust-
level controls. This reel master works directly into of the tape is reached, after playback or rewinding. ment) for 38 cm /s duplicates from 38 cm /s master
most of Pentagon's slave models. The transport has The use of transparent leaders of sufficient length tape: ±1.5 dB from 40 Hz 16 kHz ')19 cm /s duplicates
direct drive dual speed synchronous capstan motor at both tape ends prevents it from running off the 70
66
 The newest product from ORTOFON
The ORTOFON cutting amplifier GO 701,
has been designed with careful
consideration for high power output
and minimum IM and harmonic
distortion. The amplifier is constructed
-
ORTOFON
CUTTING EQUIPMENT FOR
for a sine wave output of 500 watts
(peak power of kW) which makesI

it possible to cut peak velocities of more

than 30 cm /s even at 20 kHz.
THE ULTIMATE IN TRANSFER
The transfer of such high power,
particularly in the treble region is normally
prevented by the rising impedance of
FROM TAPE TO DISC
the cutter head. However, in this
amplifier a special four pole impedance
matching network is inserted between
the output stage and the Cutting Head.
This network converts the complex
vax
impedance at the output into a real load,
essentially resistive, throughout the
entire audible frequency range. Li
Cutting amplifier GO 701 works in ('l i i
conjunction with
Correction Amplifier CPS 691
Monitoring Power Amplifier GKS 681
Logarithmic Converter SSj 701
Cutting Head DSS 661
Cutting Amplifier LV 701

Exclusive UK distribution

FELDON AUDIO LTD

126 GREAT PORTLAND STREET,
LONDON WI 01 -580 4314

* Dolby A36I Revox High and for hire. Speed A77

* Revox Industrial High Recorders from Speed £210.

* All leading makes supplied including Ferrograph,

Quad, Tannoy, Spendor, Uher 4000/4200/4400,
Teac,
Report IC Recorders.

BAILEYS
131 The Parade, High Street, Watford WDI INA
Tel. Watford 34644

-IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII'L-

HIGH SPEED COMPACT CASSETTE

COPYING SERVICES
* Central London
* Cassette copies in minutes
* Io to IO,000
* Write today for rate card 4 to 20 cassettes 3toll duplicates
every 4.5 minutes every 9 minutes
- MAGNEGRAPH-EUROTEL
I Hanway Place, London WI (Jnct Oxford St/ FraserPeacock Associates Limited
94 High Street Wimbledon Village London SW19
Tott Ct Rd) Tel o1 -637 1225 or of -58o 2156 fpa 01.947 2233 sols UK distributors of !Monies

IIIIIIIIIIIIIIIIIIIIIIIIIIIIdIiIIJIIIIiIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIr
STUDIO SOUND, APRIL 1973 67
3M announce a double.side.c
in the quality of
professional recording
New Scotch 206.

1. A new oxide coating that gives

a 3 db increase in signal -to -noise
ratio,

,.<..
C°a 1CM DJ
CalWTII-11 i
EXCL.USII E ILI"
BqCK TQEÁTME nil T
MUCaAa aM !M{b9 ia[
mprovement 3M have been at the forefront of recording
tape development for many years. Now they
offer a new dimension in recording perfection
with their new Scotch 206 professional tape.
This remarkable product is the result of
technological breakthroughs in the coatings
¡ape. on the recording and backing surfaces.
1. A new oxide recording surface
After several years of laboratory research
JI have developed a proprietary oxide which
makes possible a 3 db increase in signal -to -noise
ratio. This means you have the latitude to
capture the extremes of frequency and output
without sacrificing any pure sound quality.

+10- No206
{

Premium Low Noise Tape

2.:\ new matt back coating Premium Low Noise

No.206

which ensures better handling Tape 1 -'f-r

and reduces head wear. No 206 and

Premium Low Noise
Tape

_ -
Bias ed Noise Out put
by ya Octaves

1 1 1 1 I 1 1 I I
1 1 1

100 300 500 1K 3K 5K 10K15K

FREOUENCY,Hr
DYNAMIC RANGE; Recording at 15 ps. í

Scotch 206 tape also considerably reduces

accumulated noise on multitrack recordings -
a major problem up to now.
It is also very tough, resists scratching and
prevents drop outs caused by tape debris.
2. A new matt back coating
The new back coating improves the tape's
handling characteristics, prevents slipping and
ensures more uniform winding.
It also helps to guide the tape more
accurately across the recording heads, reducing
expensive head wear.
'The backing is tougher, more scratch -
resistant than its rivals. And since it is
electrically conductive, dust and dirt are not
attracted and held to it.
Scotch 206 tape is compatible with any
professional recording system and is available
in ", I" 1" and 2" widths.
1 ,

For further details fill in the coupon below.

To: Mr. R. Haworth, Magnetic Products, SS/4/73

:;NI United Iíingdom limited,
3M House, Wigmore Street, London, w1A lET.
Please send me further details about Scotch 206
professional recording tape.
Name
Position
Thm unique back coating gives Address
Scotch 206 tape a more even wind.
Compare it yourself with the
ordinary tape on the right, abovt_. Tel. No
3M 2040 Scotch is a tradomark of 3M Company
 TAPE DUPLICATORS mode prevents tape creeping during loading. high, accepts TDC. Two transports mounted at
Special tape guides and supply spindle torque 67° angle for operating convenience.
assure accurate tape tracking and minimise tape Finish: Stainless steel front panel. Console -black
(from 38 cm /s master tape): d 1.5 dB from 40 Hz skew. An over -sized capstan and self -aligning anodized aluminium, vented top and side panels,
14 kHz') 19 cm /s for 9.5 cm /s duplicates (from 19 pressure roller provide positive, smooth tape drive. removable back.
cm /s or 38 cm /s master tape): f2 dB from 60 Hz A three -cassette slave module panel is standard Note: The Telex 300 series replaces an earlier
to 12 kHz'). 480 mm rack -mount size. The module is fitted with series, the 235. The 300 series is identical to its
Signal to noise ratio: for 38 cm /s duplicates, premium duplicator record heads of the desired predecessor but with 76 cm /s master transport
60 dB (full track); for 19 cm /s duplicates, 57 dB track and channel configurations. The hinged speed.
(full track); for 9.5 cm /s duplicates, 50 dB (half track). rear -panel match box contains the same adjustments Price:
Permissible ambient temperature: (for specified as the open -reel slave. Track two channel system
performance): up to 40 °C. Head configurations are available in half -track 86476 -10 three slaves £1,660.
Power supply: 220V, 50 Hz or 110V, 60 Hz. single -channel and two -channel, and in quarter-track 86476 -11 six slaves £2,015.
Notes two -channel and four -channel. In addition, full - 86476 -12 nine slaves £2,235.
(1) measured with wow and flutter meter type t, ack head configurations are available for open -reel Quarter track four channel system
Gaumont Kalee 740. duplicators. Any configuration is always duplicated 86835 -06 three slaves £2,155.
(2) measured with wow and flutter meter type in a single pass. 86835 -07 six slaves £2,660.
EMT 420. Open -reel slaves with 6.25 mm four -channel configu- 86835 -08 nine slaves £3,110.
(3) measured with BASF tape LGR for tape speed rations can be used to reproduce four -channel Portable rewind for three cassettes £76.
of 38 cm /s and 19 cm /s and with BASF tape LGS 35 monoaural tapes. However, due to the narrow width
for tape speed of 9.5 cm /s. of cassette tape, four -channel monoaural program-
(4) output voltage with respect to a tape flux of ming on cassettes is not recommended. Series 300 CS -1 reel to cassette duplicating
2u.Wb. Consoles system
Telex duplicators come in consoles for table or Frequency response: 30 Hz to 10 kHz ±3 dB at
bench height placement. Console panels are slan- 4.75 cm /s.
ted. Louvred top panels provide air circulation for Auxiliary input sensitivity: 500 mV, 50k ohms
the equipment. Side panels contain ports with impedance.
TELEX Monitor output: 1V to 25k ohms minimum load.
Agents: Avcom Systems Ltd, Newton removable covers for connecting cables. Each
console accepts two transports and one amplifier Crosstalk rejection : half track, two channel,
Works, Stanlake Mews, London W12 7HA. 50 dB at kHz; quarter track two channel, 30 dB
chassis. Thus, a basic system of one master and 1

Tel : 01 749 2201. one slave transport and all associated electronics stereo channel separation at 1 kHz *; quarter track,
Telex tape duplicating systems consist of the open - are contained within a single, table tep console. four channel 30 dB stereo channel separation at
When slaves are added to a system, consoles may 1 kHz, 45 dB adjacent stereo program crosstalk
reel series 300 -1 and the reel -to- cassette series
300 CS -1. be purchased as required. rejection at
kHz *.
1

A variety of track and channel configurations are *not recommended for individual monophonic
available which may be intermixed within a system. Series 300 1 open reel duplicating system recordings.
Openreel and cassette slaves may be interfaced Signal to noise ratio: within 3 dB of master tapes.
within a system. To expand a basic system, open Illuminated meters: One for bias adjustment.
Technical specification ASA standard VU meters for each program channel.
reel or cassette slaves can be added for a total Frequency response: meet or exceed ±3 dB 80 Hz
complement of ten slaves without additional elec- Equalisation : front panel switching. Standard
to40 kHz at 38 cm /s; f3 dB 40 Hz to 20 kHz at 19 NAB and EIA.
tronics or modifications. cm /s; 9.5 cm /s copies 40 Hz 10 kHz ±3 dB; 4.75
The systems are solenoid controlled and are oper- Distortion : less than one per cent at 1 kHz at 0 VU
cm /s copies 40 Hz to 50 kHz ±3 dB. at 19 cm /s.
ated by push- buttons from the master console. Auxiliary input sensitivity:
Hysteresis synchronous capstan drive motors are
500 mV, 50 k ohms Bias frequency : 300 kHz.
impedance. Tape speed : 19, 38 and 76 cm /s (master transport),
operative when the ac power is switched on so that Monitor output: 1V into 25k ohms minimum load.
tapes are always duplicated at true speed from 19 and 9.5 cm /s (cassette).
Crosstalk rejection : Better than 50 dB at all Long term speed regulation: 0.5% (master),
beginning to end. All tracks of a master tape can be frequencies.
simultaneously copied in one pass. Automatic 0.8 % (cassette).
Signal to noise ratio: less than 3 dB degradation Capstan and drive bearing: oil impregnated
features stop the system at the end of a duplication from master tapes; 55 dB peak S/N ratio at 19 or bronze, no lubrication required.
run or if the master tape should break. However, 38 cm /s.
should a tape on a slave unit break, only this slave Capstan drive motor: two speed hysteresis
Illuminated meters: one for bias adjustment ASA synchronous.
becomes inoperative, allowing the duplication standard VU meters for each program channel.
process to continue uninterrupted on all other Wow and flutter: 0.25% rms.
Equalisation : front panel switching. Standard Control circuits: 24V dc.
slaves. A photo electric sensor allows for program- NAB and EIA.
ming and captive tape operation on the master Master fast forward/rewind: 365m reel, 60s.
Distortion : less than 1 % THD at 1 kHz at 0 VU at Counter: three digit decimal reset -table. On
transport. By adding transparent windows and 19 or 38 cm /s.
leaders to the master tape, this tape may be pro- master transport only.
Heads: Laminated, hyperbolic ground, no pressure Power requirements: 265W maximum for basic
grammed for duplicating and it becomes necessary pads required.
to reload the master for a repeat run. system at 105 to 130V ac 50/60 Hz. Each additional
Bias frequency: 300 kHz. slave 75W maximum. Also available for 210 tc 240V
Telex duplicating systems can be virtually custom - Long term speed regulation : 0.5%.
used with standard components. It is possible, for ac 50/60 Hz.
Capstan Drive: flutter -filter multiple belt drive. Console dimensions: 813 x 533 x 240 mm (hwd).
example, to make quarter track copies from a half Capstan Flywheel: dynamically balanced.
track master tape. Or, tape speeds can be changed; Equipment mounted at 67° angle for operating
Capstan and reel bearing: oil impregnated bronze, convenience.
a 4.75 cm /s master can yield 38, 19 or 9.5 cm /s open -
reel copies or4.75 cm /s cassette copies. Or a system
may incorporate both cassette and open -reel slaves.
no lubrication required.
Capstan drive motor: two speeds hysteresis
Finish: Stainless steel front panel. Console
black anodized aluminium, vented top and side
-
synchronous. panels, removable back.
All tape motions are controlled by push- buttons. Spooling motors: standard shaded four pole
The playback heads, without pressure pads, are Note: The Telex 300 series replaces an earlier
torque motors. series, the 235. The 300 series is identical to its
protected by tape lifters during fast forward or Wow and flutter: 0.17% rms at 38 cm /s 0.2% rms
rewind modes. The transport panel is standard predecessor but with 76 cm /s master transport
at 19 cm /s. speed.
480 mm rack -mount size. Master transports are Brake: differential balanced braking, self energising
fitted with playback heads of the desired track and Price:
in the event of power failure. Half track two channel system
channel configuration. Control circuits: 24V dc. 86781 -21 one slave £1,680.
The open -reel slave transport is identical to the Transport controls: push- button relay. Rewind, 86781 -23 three slaves £2,178.
master transport except no digital counter is pro- stop, play, fast forward. 86781 -25 five slaves £2,840.
vided and the unit is fitted with special duplicating Reel size: 18 cm maximum. 86781 -27 seven slaves £3,522.
record heads of the desired track and channel Fast forward rewind: 365m reel, 60s. 86781 -29 nine slaves £4,200.
configuration. A hinged rear -panel match box Counter: three digit decimal, reset-table. On
contains individual channel audio record level Quarter track four channel system
master transport only. 86783 -21 one slave £2,150.
adjustments, bias current adjustments and bias trap Power requirements: 340W maximum for basic 86783 -23 three slave £2,725.
adjustments. system at 105 to 130V ac 50/60 Hz. Each additional 86783 -25 five slave £3,460.
The cassette slave module contains three cassette slave 150W maximum. Also available for 210 to 86783 -27 seven slave £4,180.
transports with a common, two -speed hysteresis 240V ac 50 /60 Hz. 86783 -29 nine slave £4,910.
synchronous motor. Cassette transports operate Console dimensions: 813 mm high, 533 wide, Special head track configurations available;
at 19 and 9.5 cm /s. Positive braking in the stop 457 mm deep at base. Front panel base 240 mm prices on rapt est.
70
The Telex copier duplicating just track one or track two or both). Red colleges. In all cases these systems have been
This is a desk top unit designed to be operated by motion light for each transport to indicate stoppage designed and built from standard modules and
non -technical personnel in business, industry, of tape travel. parts used in the normal production of TRD's
education, libraries and the office. It is so simple to Equalisation: RIAA and DIN standard. professional tape machines.
operate it can be used by anyone without special Weight: less than 13.5 kg. Current enquiries are being quoted using compo-
instructions. Small size and compact styling suit the Dimension : 40 cm x 45.5 cm x 19 cm (wdh). nents from the Series 700 tape machine. A recent
copier to the constantly growing applications where Warranty: one yea.. quote to a UK University is typical and is summarised
cassettes are used fot communication or information below.
storage. One master tape machine with half track mono
The copier is available in two configurations. The record /replay facility allowing the customer to use
cassette copier one (master) provides all controls TRD it as a separate machine or in the copying bank.
and makes one cassette copy from the original. It Tape Recorder Developments, Hall Lane, Two slave machines with half track mono record
has add -on capabilities for two cassette copier two Walsall Wood, Staffordshire, WS9 9AU. facility only.
(slave) modules. Each cassette copier two makes A remote control unit allowing simultaneous
two copies but relies on the cassette copier one for Tel : 054 33 5351 -3 operation of all machines. A ppm and record level
all power and control. The cassette copier two is TRD have for sometime been supplying equipment control to the slaves being included.
equipped with a single emergency stop button. for use in tape copying, especially to universities and Price: Ex works for the complete unit £950.
Both units are identical in size and styling.
The cassette copier one features two button opera-
tion. Illuminated rewind and copy buttons and a
track selector provide complete control. The unit
is automatically switched on when the original
(master) cassette is inserted. The operator sets the
track selector to copy channel one or two or both
and then activates the rewind button to assure that Late entry
cassettes are copied from the beginning of the
tape. Indicator lights now tell the operator to push
BIAS 0.05% at 152, 76 and 38 cm /s, better than 0.1 % at
Bias Electronics, Unit Coombe Trading
8, 19 cm/s.
the copy button. Old material on the selected
Estate, 1121120 Coombe Lane, London Spool capacity: 29 cm Will accept, NAB, Euro-
channels is automatically erased as the cassettes pean and Cine centres.
SW20.
are copied, but existing material on other tracks is Tape tension : Electronic servo tape tension system
preserved. This eliminated the need for a bulk Tel: 01 947 3121.
controlling the feed spool. Tension held within
eraser. When copying is completed, cassettes are ±10g throughout the length of a NAB spool. Ten-
automatically erased as the cassettes are copied, Description
Bias Electronics, the manufacturers of the 13E1000 sion normally adjusted to 80g for 38 cm /s operation.
but existing material on other tracks is preserved. Can be adjusted from 0 to 120g as required.
This eliminated the need for a bulk eraser. When tape recorder, also market the 8E1000 tape deck as
a separate unit with high speed versions for use in Rewind time: 100s for 730m of tape maximum.
copying is completed, cassettes are automatically Start time: to rated speed better than 0.1s to 0.1%
rewound to start. The unit returns to stand -by or tape duplicating systems available to order.
wow and flutter better than 1s (both measured at
automatically shuts -off when the original cassette is 38 cm /s).
removed. A manual emergency stop, which stops all Technical specification Mounting : standard 480 mm racks mounting or can
tape motion, is activated by pushing both the copy tape transport be supplied in console if required.
BE1000 6.25 mm
and rewind buttons simultaneously. Formats: 6.25 mm as above but 12.5 and 25 mm
Power requirements: 110, 120, 200, 220, 240V, 50 Hz
The cassette copier features all solid state circuitry versions are also available.
(60 Hz to order).
and all electronics are on modular plug -in boards Prices: from £376 for a 19/38 cm /s deck.
Speeds: 19/38, 38/76, 76/152 cm /s.
for easy serviceability. Removing the case bottom Available: ex works London, or from local agents
Speed stability: better than +0.2%.
screws provides complete accessibility to all
Wow and Flutter (peak weighted): better than abroad.
electronics and any board can be replaced in the
field in minutes. The Telex copier is colour coordi-
nated in ivory, blue and charcoal.

Technical specifications
Duplicating speed: 76 cm /s.
Rewind speed: 152 cm /s.
Frequency response: 30 -10 kHz.
Automatic erase: track selectable.
S/N ratio: 45 dB below record level (3 per cent thd).
Crosstalk rejection : 50 dB minimum at kHz. 1 Value -added tax
Head configuration: half track two channel. Readers, particularly those not registered under
Controls:lighted amber rewind button, lighted blue VAT, are reminded that all prices in the foregoing
copy button. Three position track selector (for surveys are exclusive of value -added tax.

CHILTON 10/2 MARK 2

BASIC FACILITIES:
Prefade listen and auxiliary send on all 10 input channels. Break jacks on all
inputs and output groups. HF and LF equalisers, talkback and switchable
(line or monitor) ppms. Line -up oscillator: 40 Hz, 100 Hz. 1 kHz, 10 kHz
and 15 kHz ±0.5 dB. Illuminated red /green cue pushbuttons.
External stabilised 24V supply with auto overload cutout.
Low noise: -122 dBm ref 600 ohm source over 20 kHz bandwidth.
Low distortion : 0.05;á at +10 dBm out, 1 kHz.
Low crosstalk : -55 dB, 1 kHz.
Bandwidth : 30 Hz to 18 kHz +1 dB.
Dimensions: 570 x 466 x 233 mm.
Weight: 9 kg.
PRICE: From £275.

MANUFACTURER: MAGNETIC TAPES LTD., CHILTON WORKS,

GARDEN ROAD, RICHMOND, SURREY, ENGLAND. (Tel: 01 -876 7957)

STUDIO SOUND, APRIL 1973 71

 REVIEWS

INFONICS 102 necessarily fully rewound. This happens

because the copier decides to stop the trans-
CASSETTE COPIER ports a short time after the right hand hub of
the master cassette stops at the end of tape.
Because the capstan drive is not used in the
BEFORE PROCEEDING with the details of rewind function, the rewind speed depends
the Infonics cassette copier, it should be men- upon internal friction in the cassettes with the
tioned that the quoted specification is taken result that the copies may take potentially
from the instruction and service manual for longer to rewind than the master and therefore
the copier, and is not a sales specification. The not be fully rewound when the master stops.
Insertion and withdrawal of the cassettes
agents for the copier were at pains to point out
was positive and simple and the location of
that the unit is sold for the purpose of copying
cassettes containing speech recordings and that the cassettes in the copier was satisfactory.
it has been sold to many religious organisations
There was, however, no lockout facility for
and similar bodies for this purpose. sensing the presence of the record interlock
No doubt, many engineers will regard a tabs in cassettes. It was therefore possible to
cassette-to- cassette copier as an instrument of record inadvertently on already recorded
doubtful virtue but it does provide a quick and cassettes. While the copier is not fitted with
simple means of copying recorded cassettes for erase heads, it would still ruin a recording.
such needs as sales promotion, language The overall mechanical construction of the
laboratories, personnel training and similar copier was to a high standard, and it should
applications where only speech quality is of be mentioned that the unit employs one mas-
importance. While I would have preferred to sive motor to drive each cassette transport.
MANUFACTURER'S SPECIFICATION. All the electronics are mounted on good
have reviewed a reel -to- cassette machine, Cassette playing speed: 4.75 cm /s.
Fraser -Peacock felt that there was little point Duplicating speed: 76 cm /s.
quality printed boards and are readily acces-
in reviewing their current machine because it Duplicating time (C30): minute.
1
sible once the cabinet has been removed,
is about to be replaced by a new model. I look Rewind time: 30s. which is a simple operation once a large
forward to the opportunity of reviewing the Frequency range: 40 Hz to 10 kHz. number of screws have been undone. Access
new version when a sample is available. Wow and flutter: 0.21 ;' rms per station (within to the transports and heads for cleaning is
NAB specification). really excellent as the complete top cover of
The Infonics 102 is a half -track copier which Equalisation: DIN 4.75 cm /s.
produces two copies per run of the 4.75 cm/s the copier just pulls off.
Bias frequency : 500 kHz. Rather surprisingly, the quality of the tape
master tape at a nominal tape speed of 76 Power consumption: 150W (600W surge) at 110
cm /s. As will be seen, the operation of the wind was found to be good with a variety of
to 125V ac, 50 or 60 Hz. 230V ac input available on
copier is extremely simple so that anyone who special order.
tape makes and types, ranging from C30 to
is capable of operating an office duplicator Fusing: 5A (electronics); 5A (motors); both on C90. While it is possible to copy CI20, this is
will have no trouble at all in producing copies 230V ac. really asking rather much.
of cassettes. Dimensions: 446 x 305 x 261 mm. Although the duplicating speed was not
There are only four operational controls, Weight: 15.9 kg. measured with precision, it was certainly very
Price: £900 (recommended retail). close to the specified 76 cm /s, and the rewind
all of which are in the form of pushbutton Manufacturers: Infonics Inc, 1723 Cloverfield
switches mounted on the top of the unit. The speed was about double this, depending upon
Boulevard, Santa Monica, California 90404, USA.
first control is the mains on /off switch, the Agents: Fraser -Peacock Associates, 94 High
the internal friction of the cassette being
correct operation of which is shown by a sen- Street, Wimbledon Village, London SW19. rewound. Of much more importance is the dif-
sibly bright indicator light. The remaining ference in duplicating speed between the slaves,
three operational controls effect the tape move- and this was measured by copying a cassette
ment and are the simple functions of 'stop', which was pre- recorded with an accurately
'duplicate' and 'rewind'. While there is no buttons are pressed and operation commences. known frequency. The first slave was found to
mechanical interlock between these controls, The copier then continues operations until run between 0.2 and 0.3 per cent fast, and the
the operator has to be really stupid to do the master tape has stopped, from which point second slave between 0.15 and 0.3 per cent
things wrong and no disaster could result from all cassettes automatically rewind. All this slow, representing a timing error of less than
going out of the fast rewind function into stop. works well and only one possible snag was 6s across 30 minutes in the worst case.
On the UK model of the copier there is one found. This was that, while the copier always Wow and flutter was determined by copying
further external control in the form of a toggle rewinds the master fully, the copies were not prerecorded cassettes containing 3.15 or 3 kHz
switch located at the bottom rear of the copier. tone of known low wow and flutter, and then
This switch selects the mains power for either replaying the copies on a replay machine
220 or 240V. The type of switch and its location having a well defined and low wow and flutter
are most unsatisfactory because it would be Wow and flutter across 65 performance. The measured wow and flutter
all too easy to operate the switch by accident of the copies was virtually identical for both
when, for instance, cleaning around the copier. slaves, and in both cases was better at the
In practical operation, the mastef cassette beginning of the copy than at the end of the
is loaded into the (clearly labelled) left hand copy.
transport. Rewound and bulk erased cassettes The DIN (peak weighted) wow and flutter
are loaded into the remaining two transports was measured as 0.45 per cent at the start of
and the rewind button is pressed, which copies, increasing to 0.55 per cent at the end of
rewinds all three cassettes until the master copies. As can be seen from the photograph of
transport stops. Finally 'stop' and 'duplicate' 74 0
72
THE TAPE DUPLICATING CO.
(G.B.) LTD.

the largest

INDEPENDENT
CUSTOM
DUPLICATOR
in Europe
DUPLICATORS FOR THE MAJORITY
OF BRITAIN'S MAJOR RECORD
COMPANIES AND INDEPENDENT
PRODUCERS IN EUROPE
WHY NOT FOR YOU ?
The Tape Duplicating Co., Audio Works,
Cartersfield Road, Waltham Abbey, Essex EN9 1JF
ENGLAND
(A Division of Metrosound Audio Products Ltd.)
Telephone:- Waltham Cross 31933 telex:- 25166

STUDIO SOUND, APRIL 1973 73

 INFONICS 102 REVIEW

the weighted wow and flutter waveform, by FIG. I INFONICS 102 REPRODUCTION UNIFORMITY (SEE TEXT)
far the largest component is at about 4 Hz. By BEGINNING MIDDLE ENO

stretching the imagination a little, the rms wow MASTER

and flutter could just be within the specified
0.21 per cent but none of these figures is very
good. Remembering that in practice the wow
r
and flutter from the master is added to these
figures it is quite clear that any attempts to
copy music will be hopeless and that copies of COPY 1

speech will be of marginal quality.

Uniformity of reproduction was investigated 5dB
by recording a full C90 cassette with 1 kHz
tone in the half track monophonic format, and
then copying this entire cassette. All three COPY 2

cassettes were then replayed on a quarter track

stereo recorder, the output of which was
monitored with a Bruel & Kjaer level recorder
with the pen speed set to 1 m /s. The resulting
plot (fig. 1) shows very considerable deterior-
ation of uniformity at the beginning of both
copies, reasonable performance at the middle
30s
of the copies, but a further deterioration at the
ends.

FIG. 2 INFONICS 102 FREQUENCY RESPONSE ( -25dB REF. 25pWb /mm)

COPY 1

TRACK 1

MASTER

COPY 1

TRACK 2

20 50 100 200 500 1000 2K 50 10K 20k

FREQUENCY IN Hz

The frequency response performance shown process and this result was considered to be suggested, and is likely, that back coated tapes
in fig. 2 at a recorded level of -25 dB with excellent. may alleviate this problem but, so far as I am
reference to 250 pWb /mm with a pen speeds aware at the time of writing, only one or two
of 100 mm /s and paper speed of 3 mm /s also makes of cassette tape are available with a
reveals a cyclic lack of uniformity, but the Copied tape noise back coating and they suffer from other tape
actual frequency response is quite good, with Copied tape noise was also found to be satis- problems.
3 dB points at 60 Hz and 9.5 kHz, compared factory at a level of -53 dB(A) with respect to A further point also observed during the
with the master which had 3 dB points at 40 a 250 pWb /mm with half track (mono) replay measurement of noise performance was that
Hz and 13 kHz. The comparison between the (50 dB unweighted). However, a very serious the copier was to a limited extent microphonic.
master and copies in fact improves as the snag was discovered during the exercise of While this problem is to no extent serious, and
recorded level is raised, showing the biasing measuring noise performance. It was found not in the same category as the static discharge,
of the copies and the overload margins of the that the copies contained very serious static it is necessary to ensure that the copier is not
copier's amplifiers are satisfactory. discharge clicks (similar to car ignition noise) subject to excessive vibration and is not
Reference to fig. 3 shows the third harmonic when the copier was operated in low humidity handled during copying.
distortion introduced by the copier at various conditions. This fault appeared when the rela- Finally, the matter of electrical safety was
record levels of 315 Hz tone and demonstrates tive humidity was between 40 and 50 per cent considered in terms of British Standard 3861:
the effectiveness of the internal auto gain control and was found to be present with C60 and Part 1:1965 which is concerned with the elec-
in the copier. It is in fact quite remarkable how C90 tape of BASF, EMI and 3M manufacture trical safety of office machines. While the stan-
little distortion is introduced by the copying when they were used as masters. It has been 76
74
 EAROPENER Power Handling: 100 Watts
Dimensions: 222 x 124 x 104 inches, 1.7 cubic feet
57 x 32 x 26 centimetres, 47.4 litres
Guarantee: unconditional,for 7 years
Origin: designed and made in Great Britain
Launch: Sonex 73, rooms 4029 -4031
Enquiries about the Gale GS401 Loudspeaker:
ID Gale, Gale Electronics & Design Limited
39 Upper Brook Street London W1Y 1PE
 INFONICS 102 REVIEW are concerned, the performance was perfectly
acceptable.
My feelings towards Infonics 102 cassette
copier were to treat it in much the same terms Postscript
dard's requirements were not investigated in
any detail, one or two matters were found to as a regularly used office duplicator and the During the course of this review, I contacted
require attention on the part of the manufac- comments made in this review are related to Messrs Fraser-Peacock Associates to enquire
turers. Probably the most serious matter is this type of performance requirement. The if the problem of static 'ignition noise' had been
that the colour coding of the mains lead is construction of the copier is good but I doubt experienced with the Infonics duplicator.
green, white and black, which is non -standard if the mechanics are sufficiently sound to stand It turned out that this was a known problem
for Europe and also contrary to the UK 'Elec- up to full time use, five days a week, as a and, some time after writing my review, I was
trical Appliances (Colour Code) Regulations copying machine. That is without considerable contacted by Messrs Fraser-Peacock Associates
1969'. degradation in performance. requesting me to examine a modified version of
It was also noted that the previously men- Against all this one must balance the cost. the Infonics cassette duplicator which had an
tioned toggle switch for changing mains voltage At a recommended retail price of £900, this is electrically conductive strip inserted across the
was mounted such that its metal dolly was not no cheap toy. But, if one balances this against original plastic moulded dummy erase head
earthed to the chassis of the copier, and also some 30 off £30 cassette recorders which would on the `master' transport.
that various metal ventilation panels were match the Infonics in copying speed and be This modification did effect a considerable
not earthed. probably not so good in performance, it improvement in the original static problem,
Subjective testing of the unit confirmed that becomes more realistic, particularly in view of such that the problem may not be noticed in
its performance on music was far from good the labour costs involved in loading and loud speech recordings. However, the defect
from the aspects of wow and flutter and lack unloading cassettes. If your application is still exists and will without doubt remain a
of uniformity of output, also the signal -to- appropriate the Infonics 102 may be a best cause for complaint at its modified level of
noise ratio left quite a bit to be desired. How- buy but it is definitely not recommended for severity.
ever, testing with speech provided perfectly copying any form of music recordings.
adequate results and, so far as copies of speech Hugh Ford

FIG. 3 INFONICS 102 THIRD HARMONIC DISTORTION

PJ`
4.1.,.--° INPUT/OUTPUT

LEVEL
"P"'"-V-1 250pWb/mm

COPY

MASTER

20 50 100 200 500 1000 2K 5K 10K 20K

FREQUENCY IN Hz

SYNTHESISER? PATCHING?
Build your own using Dewtron Professional Modules: Voltage -control system, Discount offers on
quantity. NEW "MODUMATRIX" INSTANT MODULAR ROUTING System to replace patching !

VOLTAGE -CONTROLLED OSCILLATOR. New VCO -2 gives SINE, SQUARE and TRIANGULAR
symmetrical outputs simultaneously. Supplied singly or MATCHED and TRACKED! 1v /Octave.
All modules obtainable separately, including ring modulator, VC filters, VC amps, Keyboards, contacts,
envelope shapers, sample /hold /envelope circuit, VC phaser, white noise, reverb. etc. Modules guaranteed
2 years. OTHER MANUFACTURERS USE Dewtron Professional Modules in their equipment ... that's
sound reasoning! ALSO COMPLETE SYNTHESISERS CUSTOM BUILT TO YOUR REQUIREMENTS.
Standard models "Gipsy" and "Apollo"
Full catalogue I5p from:
D.E.W. LTD. 254RINGWOOD ROAD,
FERNDOWN, DORSET

76
 Classified Advertisements 4 -TRACK STUDIO
Advertisements for this section must be pre -paid. The rate is 7p per word, minimum 70p. Box Nos. 20p
extra. Semi -display rates on application. Copy and remittance for advertisements in MAY 1973 issue
£4.50 HOUR
must reach these offices by 16th MARCH 1973 addressed to: The Advertisement Manager, Studio Free use of Hammond Organ, Fender
Sound, Link House, Dingwall Avenue, Croydon CR9 2TA. Amps, Hayman Drums
NOTE: Advertisement copy must be clearly printed in block capitals or typewritten.
Replies to Box Nos. should be addressed to the Advertisement Manager, Studio Sound, Link House, Dingwall Fender, RMI, Wurlitzer Electric Pianos
Avenue, Croydon CR9 2TA, and the Box No. quoted on the outside of the envelope. The district after Box Fender, Gibson, Martin Guitars, Syn-
No. indicates its locality. thesiser also available.

SITUATIONS VACANT
*Technician for Electronics Section concerned
with medical educational television and audio T. W. STUDIOS
tape recording. Starting salary up to £1300 400 Lillie Road, Fulham, London, S.W.6
depending on qualifications and experience. Tel. 01 -385 4630/0393
SOUND RECORDIST
Required by the Overseas Press and Radio Division of Day release towards ONC can be arranged.
the CENTRAL OFFICE OF INFORMATION to join a Duties include operation and maintenance of *J & B Recordings. Tape to disc -latest high
small and busy group of sound engineers servicing
equipment and tape duplicating. Further evel disc cutting, all speeds. Mastering press-
both programme and news output. The Division
produces programmes and news items for trans- details write or phone J. Cooper, Audio Visual 'rigs, studio, mobile. 14 Willows Avenue,
mission by Radio stations overseas and in the United Communication Dept., British Medical Asso- Morden, Surrey. MITcham 9952.
Kingdom. The successful candidate should be versatile
ciation, Tavistock Square, London WC1 H 9JP.
and capable of operating all types of studio and
recording and
location recording equipment. He /she will also be
required to edit tapes and to operate circuit trans-
Tel. 01- 387 4499. mjb transcription service
mission equipment to overseas radio stations. The
ability to work quickly and accurately under pressure Vinyl pressings and acetate demodiscs. Limiting,
is essential. Some late night and weekend working is
involved. Salary according to experience and qualifi-
STUDIO FACILITIES compression and equalisation facilities; high undis-
torted cutting levels with feedback cutter heads.
Booklet available.
cations on a range £1674 to £2139 per annum. Please
send postcard for application form to:
*County Recording Service. Stereo and Mono ST. MICHAEL'S, SHINFIELD ROAD,
CENTRAL OFFICE OF INFORMATION
masters, 12" vinyl pressings. SHINFIELD GREEN, READING, BERKS.
Room 53, Floor 'I', Atlantic House, Holborn Reading (0734) 84487 Member A.P.R.S.
Viaduct, London ECI
*County Recording Service. Top quality,
Roger squire
quoting reference number PE1290131 VY. Closing
date for completed forms 30 March 1973. reasonable price, quick delivery. Tel. Bracknell
4935. London Road, Binfie!d, Bracknell, Berks
*Chateau d'Herouville, 95- Herouville, France RGI2 5BS.
el. 466 48 26 or 28, are seeking for their studios
English sound engineer-must be well qualified.
Telephone or call immediately.
*Small but rapidly expanding company requires
Audio Electronics Desigrer to work on
Di Studios
The best facilities in town for
*Mobile recording van. Live sessions. Stereo.
Anywhere. Mobitrack,

HI-FI "RUMBLECURE"
01 -892 9599.

development of professional recording equip- making Audition Tapes, Jingles, (Patent 28949169)
ment for Motion Picture and TV industry in a Programmes and Sound Com-
These Patents expose the inability of the trade, and
young and enthusiastic team. Salary by mercials. For further information
its advisor's, to solve the complicated phenomena of
negotiation plus monthly profit sharing. telephone
vibration. WE DEAL DIRECT ONLY.
Knowledge of studio and film industry tech- Tel. 061-330-2836 (anytime)
niques an advantage. Box 650.
01-7228111 Black Knight, Ashton -u -Lyne, Lancs. OL6 6TA

SOUND ENGINEER
Rapidly expanding studio requires an editing dubbing
*County Recording Service. 7" vinyl discs FOR SALE-TRADE
engineer. Must be experienced and able to work to pressed on our own plant.
high standards of quality in both music and voice *Fanfare Records. Tape - disc pressings, *Professional tape only 45p. 1200ft. Agfa on
recording. Knowledge of audiovisual field also an demo's, masters, any quantity. Studio/mobile. hubs, no joins (p. and p. one box 25p, each
asset. Salary negotiable. Please write to:
Neumann disc cutter. S.A.E. brochure. 1
additional box 10p). We handle 99% of all
IAN HIGHLEY Broomfield Close, Rydes Hill, Guildford. s/h professional recording equipment. Send for
list. Jackson Studios, Rickmansworth, Herts.
Fraser -Peacock Associates Ltd., 94 High Telephone 0483 61684.
Street, Wimbledon Village, London,

*Audio- Sales.
SWl9

Technical audio sales to

YOUR TAPES TO DISC
Records made to order -7" from LI.50, 12" from L4.00.
FOR SALE
professional studios. FM and TV broadcasters. 4 -day postal service. Vinyl pressings, sleeves, labels.
Tax -free for schools, etc. We cut records for many
Several full time regional openings available in
the USA and Europe. Send resume to RC
Recording Studios, etc, and use the same equipment
for you: NEUMANN Disc Cutting Lathes -Mono and
LEEVERS -RICH 1"
Desmarais, Burwen Laboratories, 209 Middle-
sex Turnpike, Berlington, Mass. 01803.
Stereo systems. Professional tape machines with
Ferrite playback heads, Dolby A and B systems, 200W
Amplifiers, Lockwood monitors, Teletronix /Ortofon
8 TRACK MACHINE
*Enthusiastic young man (18 -21) w;th A levels Limiters. Send SAE for photo leaflet.
or ONC in electronics to woi k in recording DEROY STUDIOS (1948) PRICE £3,000 O.N.O.
studio. Interest in and know :edge of recording
essential. Phone Jerry on 01 -499 7173 for
appointment.
Hawk Street, CARNFORTH, Lancs. Tel. 2273

*County Recording Service. Stereo and Mono

Contact -
discs from your tape.
TONY LEATHER
INDIVIDUAL *Graham Clark Records. Tape to disc press- 01 -499 7173
To take an active part in expanding my small London 'rigs. 124A Station Road, Addlestone, Wey-
based outfit. This is an excellent opportunity for a bridge, Surrey. Tel. Weybridge 43367. *Sennheiser MD112 Microphone, new /boxed.
person who has a thorough technical background in Normal price £44. Special offer £32. AKG K50
audio. Must be willing to contribute in accordance COMPACT CASSETTES Phones 75 ohms £5.90. Perfectone EPGA
with the demands of an exciting and challenging
business manufacturing professional quality high power
PROFESSIONAL HIGH -SPEED DUPLICATION
Dolby B- compression and equalisation available
competitive prices on small runs -full productions
- (Pulse) £95. Special Microphone Offers: AKG
D109 £11.00. AKG D202E1 £32.00. AKG
sound systems. Substantial remuneration offered to the undertaken-music and language specialists. D190C £15.00. Sennheiser MD211 £32.00.
right person. Contact Chris Sands Sennheiser MD413 £25.00, p.p. 50p. Sennheiser
AUDIO EDUCATION COMPANY HD414 Dynamic Headphones £8.25, p.p. 30p.
Write giving full background to Box No. 651.
J. J. Francis (Wood Green) Ltd.,123 Alexandra
01 -723 6635
Road, Hornsey, London, N.8. Tel. 01-888 1662.
STUDIO SOUND, APRIL 1973 77
 *All must go. Offers invited please. Good
RA NK -KALEE homes required Leevers -Rich fin.-4 track,
RAC MIXERS E.M.I. Mono Plate, Elcom 8 in 2 out mixer.
Wow and Flutter Meters Other smaller items. Inspection welcome. No
WE HAVE MOVED ! Excellent condition reasonable offers refused. Domino Records,
One or two available at E85.00 each High Street, Albrighton, Nr. Wolverhampton.
Demand for our products has meant larger Burgess Lane & Co. Ltd., Thornton Works, Tel. Albrighton 2384.
premises! Our new address: Thornton Avenue, Chiswick, London W.4
01 -994 5752/5953 *Professional system consisting pair of I.M.F.
19 Freemantle Road, Bilton, Rugby Reference Monitors 200 watts, high speed
Tel: 0788-810877 quality Teac 7030 deck, F600 -RS stereo limiter/
Custom Built RAC Mixers for Groups, PA, *Tame those dB's ...
Plug in professional
quality FET compressor module £15.50. For
compressor by Audio & Design, two Alice
(Stancoil) crosstalk /noise suppressors with
Hospital Broadcasting, Recording, Discos,
etc the `slick operator' ...
`Voice over' module
£15.50. S.A.E. details. Cathedral Sound SS,
power supply, studio quality pre -amp with
Graphic equalisers and Peak reading output
RAC Audio Modules for building your own "Fourways," Morris Lane, Halsall, Lancs. meters, also transcriptors reference turntable,
mixers. Shure, AKG, Calrec Mikes, Stands, L39 8SX. sweep arm, stylus brush, arm fitted with Empire
etc in stock. Write, phone or visit us. 1000ZEX cartridge. Everything latest models.
Complete system cost £1,600, must sell £1,000.
SOWTER TRANSFORMERS Offers for separate items entertained. 01 -980
*Lancashire. Tandberg, Ferrograph, Tape for all purposes in 7683 (evenings).
SOUND RECORDING AND REPRODUCING EQUIPMENT
Recorders, etc. Plus over 10,000 high fidelity We are suppliers to many well -known companies,
systems. After-sales service. Holdings, Photo - studios and broadcasting authorities and were estab-
Audio Centre, 39 -41 Mincing Lane, Blackburn lished in 1941. Early deliveries. Competitive prices.
BBA 2AF. Tel. 59595/6. Large or small quantities. Let us quote.
E. A. SOWTER LTD.
WANTED
Transformer Manufacturers and Designers
7 Dedham Place, Fore Street, Ipswich IP4 IJP *Lee Electronics. The Tape Recorder and
Telephone 0473 52794 Hi -Fi Specialists wish to purchase good quality
KEY Electronics Tape and Hi -Fi equipment for cash. 400
-announce their new Edgware Road, W.2. Phone PAD 5521.
Integrated circuit Peak Programme Meters, Micro- *Replay Amplifier for E.M.I. TR52 Tape
phone Amplifiers, Mixers, Line Drive Amplifiers, etc., Machine. 061 -436 1381.
(and also Ernest Turner 642 PPM movements). FOR SALE-PRIVATE
Full details from:
Dept. ST, P.O. Box 7, Bournemouth, BH7 7BS *Vortexion C.B.L. 6H. Mint £118. Kibble,
232 Westrow Drive, Barking, Essex. Tel. 01- TAPE EXCHANGES
594 1749.
*32 -page illustrated booklet: "Hints for Tape -
*If quality matters consult first our 105 -page *Uher 4000L with leather case. Excellent
condition. List £172. Accept £110. Runcorn
talkers, International Message Making," avail-
illustrated Hi -fi catalogue with technical specifi- able to non -members: 15p. Worldwide Tape -
cations (60p). Members enjoy unbiased advis- 66180. talk, 35 The Gardens, Harrow.
ory service, preferential terms. Membership *din. recording tape. Ilford brand standard
(40p) p.a. Our associates also manufacture play. £2 per N.A.B. roll. Phone 01 -567 2746,
records from your own tapes or record the 01 -734 0072. Box No. 649.
Master at our studios (Steinway Grand). Bulk
terms for choirs, fund -raising, slim- discs. Please
*Custom-built 4 track tin. recorder, also 8 MISCELLANEOUS
channel stereo-mixer. Best offer secures.
specify requirements. Audio Supply Associa- Further details phone Carlisle 0228 29486. *Repairs. Our modern service department
tion, 18 Blenheim Road, London, W.4. Tel. equipped with the latest test equipment includ-
01 -995 1661.
*Brand new tin. s.p. professional tape. Agfa ing a wow and flutter meter and multiplex
per VO 1200ft. on Tin. spools, factory -fresh stereo signal generator is able to repair hi -fi
and boxed at £1 per reel. 6 -10 reels at 95p each, and tape recording equipment to manufac-
11 and over at 90p each (p. and p. 1 box 15p,
UNIMIXER STUDIO 4 and 6 MIXERS turer's standards. Telesconic Ltd., 92 Totten-
2 boxes 25p, each additional box 5p). Jackson ham Court Rd., London W.1. Tel. 01 -636 8177.
Each channel can be switched to accept 5 different
inputs, choice of DIN, Cannon, jack -sockets, slider Studios, Rickmansworth, Herts. ' Telephone *Tape and Cassette Recorder Repairs by
faders, tone controls, PPM. Overall noise is better Rickmansworth 72351. Specialists. The Tape Recorder Centre, 82
than -127 dBv with a 200 ohm source (using 20 kHz
band with filter). Mains or battery powered. Prices *Allen & Heath 10 channel stereo mixer. Fold High Holborn, London W.C.1.
from £87 (as with the successful 45 range, supplied back, echo send, panning on all channels. *Tape -Heads reconditioned. Guaranteed
directly to users) only from: V.U's and P.P.M's. Effects equaliser. Space satisfaction. Send worn head enclosing £2 to
SOUNDEX LTD for extra channels. £320 o.n.o. 2 AKG P20 Sara Electronics, Fawkham Avenue, Longfield,
18 Blenheim Road, London W4 IES 01 -995 1661
£30 each. 01 -437 8184 daytime. Kent.

INDEX TO ADVERTISERS
Acoustical Mfg Co. Ltd. .. .. 16 C.T.H. Electronics .. .. 47 Midas Amplification . . .. 14
Acoustico Enterprises Ltd. .. 12 D.E.W. Ltd. .. .. 76 Millbank Electronics .. . .. 79
Action Video Ltd. .. .. .. 43 Dixons Technical Ltd. 41 Miniflux Electronics Ltd. . . 53
A.K.G. Equipment Ltd. .. .. 19 Eagle International 10, 11 Minnesota Mining & Mfg. Co. Ltd. 21,68,69
Alice (Stancoil Ltd.) .. .. 33 Electronic Music Studios (London) Ltd... 8 Monks, Keith, Audio Ltd. .. 47
Allen & Heath Ltd. .. .. 39 Electrosonic Ltd. .. .. .. .. 14 MSR Electronics Ltd. .. .. 59
Apollo Electronics Ltd. .. .. 8 Feldon Audio Ltd... .. 67 Neve, Rupert, & Co. Ltd. .. 80
A.P.R.S. .. .. 39 Fraser -Peacock Associates Ltd. .. 4, 59, 67 PSP Electronics Ltd. .. 45
Audio Applications Ltd. .. .. 29 Future Film Developments Ltd. .. 8 Quad /Eight Electronics .. 23
Audio Design (Recording) .. 12 Gale Electronics & Design Ltd. .. 37, 75 Rola Celestion Ltd. .. 53
Audix, B. B., Ltd. .. .. .. 18 Grampian Reproducers Ltd. .. 53 Rumble, C. H., Ltd. .. 39
Automated Processes Inc. . 49 Grundig (GB) Ltd. .. .. 27 Sansui Electric Co. Ltd. .. 25
AVDistributors Ltd. (Schoeps microphones) 55 ICElectrics Ltd. .. .. 29 Shure Electronics Ltd. .. 17
Baileys .. 67 Industrial Tape Applications .. 5, 7 Sonex 73 .. .. .. 6
Bauch, F. W. O., Ltd. . .. 63 Lamb Electronics ..
.

Beyer Dynamic (GB) Ltd. .. 31

. . 15 Sound Audio Electronic & Video
Leevers-Rich Equipment Ltd. 63 Techniques 53
Bias Electronics Ltd. .. 59 ..

Brenell Engineering Co. Ltd. .. 6 Lennard Developments Ltd. .. 45 Spendor Audio Systems Ltd. 4
Cadac (London) Ltd. .. .. 2 Macinnes Labs Ltd. .. .. .. 9 Starman Tapes .. 8
Calrec Audio Ltd. .. .. .. .. 45 Magnegraph -Eurotel Recording Co. Ltd. 67 T.B. Technical Ltd. .. . 39
.

Cintron Group .. .. 20 . Magnetic Tapes Ltd. .. .. .. 71 Trident Audio Developments Ltd. 13

Communication Access. & Equipment Ltd. 20 Metrosound Audio Products Ltd. .. 73 Walkers, N. 43
Published by the Proprietors, Link House Publications Limited, 10 -12 South Crescent, Store Street, London WC1E 7I3G, and Printed by Arthurs Press Limited, Woodchester,
Stroud, Glos. GL5 5P13.
First we looked at the works.
Then we worked on the looks.
It's amazing the number of good -looking
amplifiers there are about these days.
But that's the easy bit.
It's what's underneath that counts.
So we decided to make sure of the works
before we did anything else.
And we came up with our 'C' series.
A new range of three monitor or
entertainmenLpower amplifiers.
With the following features.
600 ohm bridging, floating, input.
8 ohm output.
Unique fully protective circuitry.
Distortion better than 0.2 %.
Available in 19" rack or free standing form.
Peak reading meter is switchable between
output and input.
Signal and mains inputs by XLR sockets.
M EX 301C: 30 watts, M EX 501C: 50 watts,
and MEX 1001C: 100 watts.
Quite some amplifiers.
And we finished them in stylish Havana
with anodised alloy handles.
After all that, they deserve to look good.
And they do.
Milibank
It's got to be good.
Millbank Electronics Group, Uckfield, Sussex, England. Tel: UCK (0825) 4166. From Europe: 892 -96 -4166.
Manufacturers of specialist audio equipment for industrial and entertainment applications.
Sound mixers, tuners, sound systems, loudspeakers, tuner amplifiers, audio modules and amplifiers. ITE
MILLBANK
Neve
at
Covent Garden
Neve is wherever you find the world's
finest sound - in recording studios,
in radio and TV, in theatres, concert
halls and film studios.
It's the performance of the consoles
that makes the sound of Neve.
Look at the figures achieved on this 11000111 MVO
console now in the Royal Opera
House, Covent Garden.
Distortion At +20dBm
Highest recorded figure 0.058%
Median figure 0.035%
Neve specification claim 0.075%
Noise 20Hz to 20kHz
Output stage - maximum -99.0 dBm
Neve specification claim -80.0 dBm
One channel selected -
maximum -81.5 dBm
Neve specification claim -77.0 dBm
Equivalent input noise -
maximum -125.5 dBm
Neve specification claim -125.0 dBm
For the best performance
figures in the world
choose Neve.
Write now for further
information.

Rupert Neve Er Company Ltd., Rupert Neve of Canada Ltd., Rupert Neve Incorporated,
Cambridge House, 7528 Bath Road, Berkshire Industrial Park,
Melbourn, Roystòn, Malten, Bethel,
Hertfordshire SG8 6AU, Toronto, Connecticut 06801,
England. Ontario, U.S.A.
Tel: Royston (0763) 60776 Canada. Tel: (203) 744 6230 telex 969638.
telex 81381 Tel: 416 677 6611 Hollywood Office,
cables Neve Cambridge telex 0621 7652 Tel: (213) 465 4822