1081 Channel Amplifier

Contents

Introduction 1

Installation 3

Dimensions 4

Power Requirements 5

Phantom Power 6

Output Level Control 6

Amplifier Controls 7

EMI Filter Components 8

Rear Panel Views 9

Connector Details 10

Connector Details Continued 11

Specifications 12

Service Information 13

1081 Recall Sheet - Horizontal Module 14

1081 Recall Sheet - Vertical Module 15

User Guide Issue 4.1 Page i

1081 Channel Amplifier Introduction

Introduction

The 1081 channel amplifier was first produced in 1972 to provide the mic/line-amp and EQ
sections in Neve consoles such as the 8048. A look through the credits on today’s top selling CDs
will reveal that these vintage consoles are still widely used to great effect and that the 1081 module
has become a hugely popular design classic. This is why AMS Neve have resumed production of the
1081, using the original components and construction methods.

In situations where the fader connection is not used (most Neve 45 series consoles) then there
should be no gain adjustment necessary the modules leave the factory calibrated for this
application.

In situations where a fader or a potentiometer connection is used (such as in both AMS

Neve racks AM3630 & AM3631), then the internal 5K1 resistor mounted between pin E (0v) and
pin K (fader send) of the module back connector should be disconnected and replaced by the
external potentiometer / fader.

Final gain adjustment should then be made with the modules fitted to the rack. Each 1081 module
has an adjustable pre-set potentiometer on its rear panel.

User Guide Issue 4.1 Page 1

1081 Channel Amplifier Introduction

When mounted in the AMS Neve rack, these pre-sets are accessed by removing the rack rear panel
and can be adjusted through the rear connector mounting panel.

The gain should be adjusted using the Line input with the sensitivity switch set to 0dB and the output level
controls set fully clockwise.

Apply a 0dBu 1kHz sine wave to the Line Input XLR and adjust the pre-set to give 0dBu at the XLR
output connector, normally loaded into the appropriate input impedance of the following
equipment.

Gains are now fully calibrated and the rear panel should be replaced.

User Guide Issue 4.1 Page 2

1081 Channel Amplifier Installation

Installation

The 1081 is available as a stand-alone module, or in a choice of two housings that provide power
supply, phantom power switching for each module and connectors for balanced inputs (mic and
line) and outputs:

dB
80 3·3 KHz 3·3 470 Hz 330
70 20 4·7 2·7 3·9 390 560 18 0 270 3·9
60 10

0
6·8 2·2 4·7
Hi
Q
330 680 100 150 5·6 SOLO AMS
50 10 1·8 5·6 270 820 56 82 8·2

40 +10 15 1·5 6·8

Hi
Q 220 1000 33 47 12
PH EQ +48V
PHANTOM
NEVE
MIC LINE OFF 27 18
CH1
30 10 OFF OFF 8·2 OFF 1200
OFF
20 Hz KHz 1
dB
80 3·3 KHz 3·3 470 Hz 330
70 20 4·7 2·7 3·9 390 560 18 0 270 3·9 CH2
60 10 6·8 2·2 4·7
Hi 330 680 100 150 5·6 +24V
Q SOLO 2
50 0 10 1·8 5·6 270 820 56 82 8·2 OUTPUT
Hi PH EQ
40 +10 15 220 1000 33 47 12
1·5 6·8 Q
MIC 30
20
10
LINE OFF OFF 8·2 OFF 1200 OFF 27
OFF
18 MAINS
Hz KHz

The 3U rack houses two modules mounted horizontally in a 19” rack-mounting unit. The rear panel
has XLRs for transformer balanced I/O and a 25-way ‘D’-type connector for solo and spare switch
contacts and unbalanced outputs plus an IEC connector for mains power.

dB dB dB dB dB dB dB dB

60
70
80
20
10 60
70
80
20
10 60
70
80
20
10 60
70
80
20
10 60
70
80
20
10 60
70
80
20
10 60
70
80
20
10 60
70
80
20
10
AMS
50 0 50 0 50 0 50 0 50 0 50 0 50 0 50 0 NEVE
40 +10 40 +10 40 +10 40 +10 40 +10 40 +10 40 +10 40 +10
MIC LINE MIC LINE MIC LINE MIC LINE MIC LINE MIC LINE MIC LINE MIC LINE
30 10 30 10 30 10 30 10 30 10 30 10 30 10 30 10
20 20 20 20 20 20 20 20

OFF OFF OFF OFF OFF OFF OFF OFF

15 15 15 15 15 15 15 15 PHANTOM OUTPUT
10 10 10 10 10 10 10 10

6·8 6·8 6·8 6·8 6·8 6·8 6·8 6·8

KHz KHz KHz KHz KHz KHz KHz KHz
3·3
4·7
3·3
4·7
3·3
4·7
3·3
4·7
3·3
4·7
3·3
4·7
3·3
4·7
3·3
4·7 CH1
8·2 OFF 8·2 OFF 8·2 OFF 8·2 OFF 8·2 OFF 8·2 OFF 8·2 OFF 8·2 OFF
6·8 1·5 6·8 1·5 6·8 1·5 6·8 1·5 6·8 1·5 6·8 1·5 6·8 1·5 6·8 1·5
1

5·6 1·8 5·6 1·8 5·6 1·8 5·6 1·8 5·6 1·8 5·6 1·8 5·6 1·8 5·6 1·8
CH2
4·7 2·2 4·7 2·2 4·7 2·2 4·7 2·2 4·7 2·2 4·7 2·2 4·7 2·2 4·7 2·2 2
KHz KHz KHz KHz KHz KHz KHz KHz
3·9 2·7 3·9 2·7 3·9 2·7 3·9 2·7 3·9 2·7 3·9 2·7 3·9 2·7 3·9 2·7
3·3 3·3 3·3 3·3 3·3 3·3 3·3 3·3
CH3
HiQ HiQ HiQ HiQ HiQ HiQ HiQ HiQ HiQ HiQ HiQ HiQ HiQ HiQ HiQ HiQ 3
12 0 0 OFF 12 0 0 OFF 12 0 0 OFF 12 0 0 OFF 12 0 0 OFF 12 0 0 OFF 12 0 0 OFF 12 0 0 OFF
10 0 0 2 2 0 10 0 0 2 2 0 10 0 0 2 2 0 10 0 0 2 2 0 10 0 0 2 2 0 10 0 0 2 2 0 10 0 0 2 2 0 10 0 0 2 20 CH4
82 0 2 7 0 82 0 2 7 0 82 0 2 7 0 82 0 2 7 0 82 0 2 7 0 82 0 2 7 0 82 0 2 7 0 82 0 2 70
4

680 330 680 330 680 330 680 330 680 330 680 330 680 330 680 330
Hz Hz Hz Hz Hz Hz Hz Hz
CH5
560 3 90 560 3 90 560 3 90 560 3 90 560 3 90 560 3 90 560 3 90 560 3 90
4 70 4 70 4 70 4 70 4 70 4 70 4 70 4 70 5

OFF OFF OFF OFF OFF OFF OFF OFF

CH6
33 33 33 33 33 33 33 33 6
+48V
56 56 56 56 56 56 56 56 CH7
10 0 10 0 10 0 10 0 10 0 10 0 10 0 10 0 7
Hz Hz Hz Hz Hz Hz Hz Hz
18 0 18 0 18 0 18 0 18 0 18 0 18 0 18 0
330 330 330 330 330 330 330 330
270 3·9 270 3·9 270 3·9 270 3·9 270 3·9 270 3·9 270 3·9 270 3·9 CH8
150 5·6 150 5·6 150 5·6 150 5·6 150 5·6 150 5·6 150 5·6 150 5·6
+24V 8
82 8·2 82 8·2 82 8·2 82 8·2 82 8·2 82 8·2 82 8·2 82 8·2

47 12 47 12 47 12 47 12 47 12 47 12 47 12 47 12
Hz KHz Hz KHz Hz KHz Hz KHz Hz KHz Hz KHz Hz KHz Hz KHz
27 18 27 18 27 18 27 18 27 18 27 18 27 18 27 18
OFF OFF OFF OFF OFF OFF OFF OFF

PH PH PH PH PH PH PH PH

EQ SOLO EQ SOLO EQ SOLO EQ SOLO EQ SOLO EQ SOLO EQ SOLO EQ SOLO

MAINS

The 7U rack houses 8 modules vertically in a 19” rack-mounting unit. The rear panel has XLRs for
transformer balanced I/O and a 25-way ‘D’-type connector for solo and spare switch contacts and
unbalanced outputs plus an IEC connector for mains power.

User Guide Issue 4.1 Page 3

1081 Channel Amplifier Dimensions

Dimensions

Stand-alone Module

Dimensions: Front panel 45mm x 305 mm (1.8 inches x 12 inches).

Approx 300mm (12 inches) deep behind the front panel.

Approx. Weight: 3kg (6.6 lbs)

Rack Data

19" Rack Mounting U Depth Height Approx. Weight

mm (inches) mm (inches) kg (lbs)
2 Module Version 3 400 134 (5¼) 17 (37) *
8 Module Version 7 400 311 (12¼) 46 (101) *

* Fully populated rack

The 7U unit is heavy (over 20kg) and should be handled by two persons.

User Guide Issue 4.1 Page 4

1081 Channel Amplifier Power Requirements

Power Requirements

3U 7U
Rated Voltage 100-230V AC 100-230V AC
Rated Frequency 50-60 Hz 50-60Hz
Rated Current 0.5A Max 0.8A Max
Surge Current (In Rush) Cold 31.0A 31.0A
Surge Current (In Rush) Hot 33.0A 33.0A
Earth Leakage Current Approx 1.2mA Approx 1.3mA
Warning for High Earth Leakage NO NO
Current Required
Primary Protection Fuse:
Operating Voltage 100-230V AC 100-230V AC
Fuse Rating and Type T1.6A H 250V T1.6A H 250V
20mm x 5mm CERAMIC 20mm x 5mm CERAMIC
Location IEC Mains connector IEC Mains connector
Secondary Protection Fuse:
Output Voltage 24V DC 24V DC
Fuse Rating and Type T 1.0A L 250V T 2.0A L 250V
20mm x 5mm GLASS 20mm x 5mm GLASS
Location F1 on SZN825-058 F1 on SZN825A058
Output Voltage 48V DC 48V DC
Fuse Rating and Type T 500mA L 250V T 500mA L 250V
20mm x 5mm GLASS 20mm x 5mm GLASS
Location F2 on SZN825-058 F2 on SZN825A058

Stand-alone 1081 Module

Power 192mA at 24V DC. Negative Earth

Mains Supply (rack units)

The power supply unit is a universal input type therefore no mains operating voltage setting is
required.

The mains switch on the front panel of the 3U and 7U rack units is non-illuminating.

The CH (chassis) and 0V Link should be connected or instability may result.

User Guide Issue 4.1 Page 5

1081 Channel Amplifier Phantom Power

Mains Fuse (rack units)

The mains fuse is located in the IEC mains input connector on the rear of the 3U and 7U rack units.

Secondary Protection Fuses (rack units)

Secondary protection fuses for the 24V and 48V supplies are located behind the front panel on the
power supply filter PCB SZN825-058 in both 3U and 7U rack units.

DC Power Supply Indicators (rack units)

The red LED on the front panel of both 3U and 7U rack units indicates +24V power healthy when
illuminated.
The green LED on the front panel of both 3U and 7U rack units indicates +48V power healthy when
illuminated.

Phantom Power

Phantom power can be supplied to each module by pressing the phantom power switch on the front
panel of the 3U or 7U rack. The LED in the switch will illuminate confirming that phantom power is
supplied.

Output Level Control

Each channel has an independent Output Level Control. The control is post-input, post-EQ and
pre-output. This control allows the input and EQ to operate at a higher level and then for the signal
to be returned to a normal operating level at the output.

When the Output Control is fully clockwise the output gain is unity. The output is 10dB down with
the control in the mid-position.

User Guide Issue 4.1 Page 6

 1081 Channel Amplifier Amplifier Controls

Amplifier Controls

70
dB
80
20
H.F. Controls: 5 switched frequencies, shelving or peaking curve, continuously
60 10
variable 18dB cut or boost.
50 0

40 +10
MIC LINE
30
20
10
H.F. Presence: 10 switched frequencies with continuously variable 18dB cut or
OFF

15
boost, high or low Q selection.
10

3·3
4·7
KHz
6·8
L.F. Presence: 10 switched frequencies with continuously variable 18dB cut or
8·2 OFF
6·8 1·5
boost, high or low Q selection.
5·6 1·8

4·7 2·2
KHz
3·9
3·3
2·7
L.F. Controls: 5 switched frequencies, shelving or peaking curve, continuously
HiQ HiQ

10 0 0
12 0 0 OFF
2 20
variable 18dB cut or boost.
820 2 70

680
Hz
560
4 70
390
330
H.P. Filter: 5 switched frequencies with slope of 18dB per octave.
OFF
33 L.P. Filter: 5 switched frequencies with slope of 18dB per octave.
56

10 0
Hz
270 330
18 0
3·9 PH Button: Gives 180° phase change at the balanced output.
150 5·6

82 8·2

Hz
47

27
OFF
18
12
KHz EQ Button: Selects equalisation in or out of circuit.
PH

EQ SOLO
SOLO Button: Selects channel unbalanced output and closing switch contact.

Spare Button: Switches external device as required.

dB
80 3·3 KHz 3·3 470 Hz 330
70 20 4·7 2·7 3·9 390 560 18 0 270 3·9
60 10 6·8 2·2 4·7
Hi 330 680 100 150 5·6
Q SOLO
50 0 10 1·8 5·6 270 820 56 82 8·2
Hi PH EQ
40 +10 15 220 1000 33 47 12
1·5 6·8 Q
MIC 30 LINE OFF OFF OFF 1200 OFF 27 18
10 8·2 OFF
20 Hz KHz

User Guide Issue 4.1 Page 7

1081 Channel Amplifier EMI Filter Components

EMI Filter Components

Jumpers may be fitted on the SUN870-081 I/O boards to allow the EMI filtering (three terminal
capacitors and common mode inductors) to be ‘removed’ from the signal path. This may be
desirable for those seeking sonic purity. However it must be noted that the immunity of the product
to external RF fields could suffer, and if this is the case then the jumper links should be removed.

The individual 1081 modules are offered for inclusion in the customers own housings. As such no
claim is being made regarding the immunity of these units. This will be principally governed by the
type of cabling, connectors and enclosure used. The use of screened cables and connectors is
recommended for all connections. Tests have shown that no problems with emissions as defined in
EMC standards should be present with these units.

Modules In Transit

Please note that the designs of the AMS Neve classic modules and racks are to the original Neve
specifications and are not designed to withstand transit. Should you wish to move the rack from one
location to another (for example shipping to another studio location or returning the rack to a repair
center for servicing), please remove all installed modules from the rack and package the rack and
each module separately in packaging suitable to withstand the intended transit. If modules are
installed in a rack while in transit, damage to the internal edge connectors may occur

User Guide Issue 4.1 Page 8

1081 Channel Amplifier Rear Panel Views

Rear Panel Views

AC MAINS I/P
MIC 1 LINE 1 O/P 1

CH 0V AUXILARY
MIC 2 LINE 2 O/P 2

MIC 8 MIC 7 MIC 6 MIC 5 MIC 4 MIC 3 MIC 2 MIC 1

LINE 8 LINE 7 LINE 6 LINE 5 LINE 4 LINE 3 LINE 2 LINE 1

O/P 8 O/P 7 O/P 6 O/P 5 O/P 4 O/P 3 O/P 2 O/P 1

AC MAINS I/P

CH 0V AUXILARY 7-8 AUXILARY 5-6 AUXILARY 3-4 AUXILARY 1-2

User Guide Issue 4.1 Page 9

1081 Channel Amplifier Connector Details

Connector Details

1081 Stand-alone
Wiring to 18 way Free Plug

A Hi
Mic I/P 0dBu
B Lo

C
Spare Spare Switch Contact
D

E 0V

F Hi
Line I/P 0dBu
H Lo

K
Link
L

M
Solo Switch Contact Technical
Solo Earth Link
N 0V

P Unbalanced O/P -10dBu

R Hi
BAL O/P 0dBu
Lo
S
0V
T
Solo O/P (unbalanced) -10dBu
U +24V at 192mA

User Guide Issue 4.1 Page 10

1081 Channel Amplifier Connector Details Continued

Connector Details Continued

Rear of 1081 2 Module (3U) and 8 Module (7U) Racks

25 way D Auxiliary and XLR Wiring

25 way D-Type
Wiring View

1
NC
14
NC
2
Chassis Earth
15
Unbalanced O/P -10dBu CH 1
3
Unbalanced 0V
16
Chassis Earth
4
Solo O/P (unbalanced) -10dBu CH 1
17
5
Solo 1 18 Solo Switch Contacts CH1
6
Spare 1 19 Spare Switch Contacts CH1
7
Chassis Earth
20
Spare 2 8 Spare Switch Contacts CH 2
21
Solo 2 9 Solo Switch Contacts CH 2
22
10
Solo O/P (unbalanced) -10dBu CH 2
23
Chassis Earth
11
Unbalanced 0V
24
Unbalanced O/P -10dBu CH 2
12
Chassis Earth
25
NC
13 For the 8 Module Rack :
NC
CH1 is CH1, CH 3, CH 5 or CH 7
CH2 is CH 2, CH 4, CH 6 or CH 8

XLR
Wiring View
Mic/Line I/P (Balanced) O/P (Balanced)
Plug Socket
2 1 1 2
Hi Hi

3 3
Lo Lo

User Guide Issue 4.1 Page 11

1081 Channel Amplifier Specifications

Specifications

Microphone Input: Zin 300 or 1200 ohms switched,

gain +80 to +10 dB in 5dB steps.

Line Input: Zin 10k ohms bridging, gain +20 to -15dB in 5dB steps.
Both inputs are balanced and earth-free.

Outputs: Max +26dB into 600 ohms. Zout 75 ohms ±5% @ 1kHz,
balanced and earth-free. An unbalanced output 8dB below
the level of the balanced output is also provided.

Distortion: Not more than 0.07% for +20dBm output from 50Hz to 15kHz.

Frequency Response: ±0.5dB from 20Hz to 20kHz. -3dB at 7Hz and 35kHz.

Noise: Output noise better than -42dBm from Zin 1200 ohms and
-80dB input, giving an equivalent noise of -125dBm referred to
600 ohms input impedance fed from 100 ohms. Output noise
better than - 80dBm at all line input levels.

User Guide Issue 4.1 Page 12

1081 Channel Amplifier Service Information

Service Information

Parts List index

PL31081- Channel Amplifier Horizontal and Vertical module versions:

PL31081-C Channel Amplifier

PL10306-C Dual Voltage Follower

PL10312-C Channel Amplifier Motherboard

PL10338-C High Gain Amplifier

PL10340-C Output Amplifier

PL20046 Sensitivity Switch

PL20047 Treble Switch Assembly

PL20048/4 Upper Presence Switch Assembly

PL20048/5 Lower Presence Switch Assembly

PL20049 LP/HP Filter Switch Assembly

PL20050 Bass Switch Assembly

AM3631 - 3U Rack:

AM3631 2 CH 1081 Mainframe Assembly Detail

SZN825-058 PSU Filter PCB

SSN818-036 0V Stud Filter PCB

SUN870-081 2CH I/P O/P Backplane

SYN824-128 2 Switch Phantom Power PCB

NN3726 Chassis Cable Assy

AM3630 - 7U Rack:

AM3630 8 CH 1081 Mainframe Assembly Detail

SZN825A058 PSU Filter PCB

Same as the 3U Rack

User Guide Issue 4.1 Page 13

1081 Channel Amplifier 1081 Recall Sheet - Horizontal Module

1081 Recall Sheet - Horizontal Module

User Guide Issue 4.1 Page 14

1081 Channel Amplifier 1081 Recall Sheet - Vertical Module

1081 Recall Sheet - Vertical Module

User Guide Issue 4.1 Page 15