USOO.

5908998A
United States Patent (19) 11 Patent Number: 5,908,998
Blucher et al. (45) Date of Patent: Jun. 1, 1999

54) HIGH INDUCTANCE ELECTROMAGNETIC 4,501,185 2/1985 Blucher .................................... 84/1.15

PCKUP FOR STRINGED MUSICAL 4,809,578 3/1989 Lace, Jr. ...... ... 84/1.15
INSTRUMENTS 5,111,728 5/1992 Blucher et al ... 84/726
5,221,805 6/1993 Lace ............ ... 84/726
(75) Inventors: Steven L. Blucher, New York; Michael 5,354,949 10/1994 Zwaan ....................................... 84/727
T. Altilio. Staten Island, both of N.Y. 5,399,802 3/1995 Blucher ..................................... 84/726
s s ... 5,530,199 6/1996 Blucher ..................................... 84/728
5,668.520 9/1997 Ki
73 Assignee: DiMarzio, Inc., Staten Island, N.Y. f al
Primary Examiner Stanley J. Witkowski
21 Appl. No.: 08/807,060 ASSistant Examiner Marlon T. Fletcher
22 Filed: Feb. 27, 1997 Attorney, Agent, or Firm-Baker & Botts, L.L.P.
(51) Int. Cl. ................................................. G10H 3/08 (57 ABSTRACT
52 U.S. Cl. ................................. 84/728; 84/723; 84/725; An electromagnetic pickup for Stringed musical instruments
84/DIG. 24 has at least one bobbin mountable to the instrument beneath
58 Field of Search .............................. 84/723, 725-728, the instrument's Strings, each of the bobbins having a body
84/DIG. 24, 730–731 and a coil wrapped around the body, the body having one or
more holes therethrough positioned below the Strings. A
56) References Cited magnetic device for generating a magnetic field around the
U.S. PATENT DOCUMENTS bobbins and one or more pole pieces extended through the
holes is also included. Ferromagnetic material is positioned
2.896,491 7/1959 Lover ....................................... 84/1.15 within the body of one or more of the bobbins or between the
3,588,311 6/1971 Zoller ....................................... 84/1.15 bobbin(s) and the musical instrument to increase the
3,711,619 1/1973 Jones et al. ... 84/1.15 devices inductance
3,916,751 11/1975 Stich ........................................ 84/1.15
4,372,186 2/1983 Aaroe ....................................... 84/1.15
4,442,749 4/1984 DiMarzio et al. ....................... 84/1.15 47 Claims, 4 Drawing Sheets
U.S. Patent Jun. 1, 1999 Sheet 1 of 4 5,908,998

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U.S. Patent Jun. 1, 1999 Sheet 2 of 4 5,908,998

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U.S. Patent Jun. 1, 1999 Sheet 3 of 4 5,908,998
U.S. Patent Jun. 1, 1999 Sheet 4 of 4 5,908,998

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HIGH INDUCTANCE ELECTROMAGNETIC So also increases the inductance, resistance and capacitance,
PICKUP FOR STRINGED MUSICAL resulting in a higher impedance of the pickup. This has the
INSTRUMENTS undesirable result of reducing the pickup’s efficiency and
dulling the instruments tonality, especially at the lower
SPECIFICATION pitches.
This invention relates to transducers, or electromagnetic While it is known in the prior art that the inductance of a
pickups, for musical instruments and more particularly, to magnetic transducer (or pickup) will have a direct bearing
pickups for electrical String instruments which provide a on the tonality or Sound produced by the instrument, no
truer, more pleasing tonal quality through increasing attempt has been made to adjust the amount of inductance of
inductance, while maintaining a lower impedance. a pickup, independent of the other parameters which con
tribute to the impedance of the pickup.
BACKGROUND OF THE INVENTION
It is a primary object of the present invention to provide
As described in U.S. Pat. No. 4,501,185, granted Feb. 26, an electromagnetic pickup having a reduced Sonic harshness
1985 to one of the inventors named in this application, 15
due to an increased inductance without a corresponding
Steven Blucher, electromagnetic pickups are used with increased DC resistance or capacitance
Stringed musical instruments, Such as electric guitars, to A further object of the present invention is to provide such
convert the vibrations of “picked' strings into electrical results in a hum-cancelling pickup while maintaining the
Signals for Subsequent amplification into Sound. The pickups pickup’s hum-cancelling capability
usually comprise a magnet System, including one or more
permanent magnet elements and one or more pole pieces SUMMARY OF THE INVENTION
made of magnetic or ferromagnetic material to establish a
magnetic field within which the Strings vibrate, and coils The present invention overcomes the prior art limitations
wound on one or more bobbins disposed in the field to by providing additional ferromagnetic material in the gaps
generate electrical Signals corresponding to flux variations in between the pole pieces of a pickup bobbin and/or beneath,
the field due to the strings vibrations. These electrical 25 around and/or in close proximity to the bobbin. This
Signals are amplified into musical Sounds by circuits and arrangement has the advantage of increasing the inductance
equipment well-known to those skilled in the art. of the pickup without causing a corresponding increase in
Although the embodiments presented herein include pole the pickup’s DC resistance and impedance. Thus, a Sound
pieces, it should be understood by those skilled in the art that with better tonality and leSS harshness results.
one or more permanent magnets may be positioned within The invention provides an electromagnetic pickup device
the pickup’s bobbin body or bodies, in a manner such that for a Stringed musical instrument having at least one bobbin
the top and bottom edges of the magnet constitute different mountable to the instrument beneath the instrument's
polarities, without the necessity of pole pieces of any kind. strings, each of the bobbins having a body and a coil
Furthermore, where pole pieces are used and constitute 35
wrapped around the body, the body having one or more
actual magnet devices, it is known in the art that a separate holes therethrough positioned below the Strings. A magnetic
permanent magnet element is not necessary to create the device for generating a magnetic field around the bobbins
magnetic field. and one or more pole pieces extended through the holes are
Typically, where pole pieces are used in the pickup also included. A crucial part of the invention is the presence
implementation, they are disposed through holes in the 40
of ferromagnetic material positioned within the body of one
bobbins and the pickup itself is generally mounted on the or more of the bobbins and/or beneath, around and/or in
face of the instrument So that at least one pole piece is close proximity to the body to increase the devices induc
Situated below each String. The bobbins are arranged So that tance. The material may be specifically placed between the
the pole pieces are within the coils to allow the magnetic bobbin(s) and the musical instrument.
field developed by the pole pieces and/or permanent magnet 45
It is preferable that the magnetic device include at least
to envelope the coil. Each String, when Set into motion, one permanent magnet positioned in close proximity to the
causes variations in the magnetic field in the vicinity of the bobbins to create the magnetic field therearound. The first
pole piece or pieces and the variations are converted into edge of the magnet preferably constitutes a magnetic north
electrical Signals by the interaction of the magnetic field pole and the Second edge of the magnet preferably consti
with the coil. 50
tutes a magnetic South pole.
It is generally understood by those skilled in the art that In one preferred embodiment, the ferromagnetic material
the efficiency of an electromagnetic pickup is measured by is positioned between the holes of the body of one or more
how much output voltage can be produced with the Smallest of the bobbins and is cylindrically shaped like plugs.
amount of impedance, resistance and inductance. In another preferred embodiment, the ferromagnetic
Unfortunately, pickup efficiency has often been Sacrificed in 55 material is positioned beneath the body of one or more of the
the prior art due to other concerns. For example, as discussed bobbins. Preferably, ferromagnetic material is shaped in the
in U.S. Pat. No. 5,530,199, granted Jun. 25, 1996 also to Mr. form of one or more Strips attached to at least one of the
Blucher, the introduction of a Second coil to cancel hum in edges of the magnet. Preferably, the magnet has at least one
a Standard hum-cancelling pickup is accompanied by an metallic Strip attached to one of more of its edges and the one
increase in resistance, impedance and inductance, thus 60 or more Strips of ferromagnetic material are attached to an
reducing the efficiency of the pickup. outer edge of the metallic Strip(s).
A common complaint regarding the tonality of electric It is also preferable in these embodiments for the elec
guitars (as well as other electronic stringed instruments) is tromagnetic pickup to have a first and a Second hum
that the Sound produced is too harsh. This harshneSS is cancelling bobbin. Preferably, the first hum-cancelling bob
particularly evident at higher pitches. One way of eliminat 65 bin has a gauge of wire different from the Second hum
ing or reducing the harshneSS has been to increase the cancelling bobbin Such that the Second hum-cancelling
number of turns of wire in the coil or coils. However, doing bobbin has a resonant frequency lower than that of the first
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hum-cancelling bobbin. In this arrangement, the ferromag features, elements, components or portions of the illustrated
netic material is, preferably, positioned within or beneath the embodiment. Moreover, while the subject invention will
body of the second hum-cancelling bobbin, thereby further now be described in detail with reference to the figures, it is
emphasizing and accentuating the differing frequencies. done So in connection with preferred embodiments. It is
Another preferred embodiment of the present invention intended that changes and modifications can be made to the
provides an electromagnetic pickup device for a Stringed described embodiments without departing from the true
musical instrument having an upper bobbin positioned Scope and Spirit of the Subject invention as defined by the
above a lower bobbin, each of the bobbins having a body and appended claims.
a coil of wire wrapped around the body. In this DETAILED DESCRIPTION
configuration, the bobbins are mountable on the instrument FIGS. 1 and 2 illustrate one of the preferred embodiments
below the Strings. The coils have axes perpendicular to the of the present invention. While pickup 10 is shown to be a
strings and at least one of the bobbin bodies has two or more dual-coil pickup, the present invention can be similarly
holes therethrough which may be positioned below the applied to a Standard Single coil pickup Such as those
Strings when the device is mounted to the instrument. Also disclosed in U.S. Pat Nos. 3,588,311 and 3,711,619. Pickup
included are a magnetic device for generating a magnetic 15
10 includes base plate 12 consisting of a rigid, non-magnetic
field around the bobbins and one or more magnets (pole material Suitable for mounting to the face of a Stringed
pieces) extended through the holes. Again, a crucial part of musical instrument Such as an electric guitar (not shown). To
the invention is ferromagnetic material which is positioned enable mounting, base plate 12 includes mounting foot 12a
within or beneath the lower bobbin body to increase the at each of the plate's two ends. The strings 14 of the
devices inductance as described above.
instrument are shown Schematically by dashed lines. Per
Preferably, the upper bobbin coil has more turns of wire manent magnet 16, having one longitudinal edge portion
than the lower bobbin coil and the wire of the lower bobbin constituting a magnetic north pole and an opposing longi
coil has a heavier gauge than the wire of the upper bobbin tudinal edge portion constituting a magnetic South pole (as
coil. designated in FIG. 2), is positioned on base plate 12.
25
It is also preferable to include an integral plate of mag Alternately, more than one magnet may be used to create the
netic material having a base disposed between the bobbins magnetic field. Magnet 16 is preferably about as long as base
perpendicular to the coil axes and two Side walls extending plate 12 and may be positioned between two metallic Strips
upwardly and perpendicularly from the base about the 18 and 20 which bear against magnet 16. Metallic strips 18
bobbin. and 20 are of appropriate magnetizable material and their
One advantage of increasing the inductance of the lower length is, preferably, about the Same as that of magnet 16,
passive hum-cancelling bobbin is that it permits the number Thus, Strip 18 constitutes a magnetic north pole and Strip 20
of wire turns of the upper bobbin to be higher than the constitutes a magnetic South pole.
number of turns of the lower bobbin. Substantially reducing Strips 18 and 20 have holes so that threaded pole pieces
the number of turns of the lower bobbin while maintaining 35 8 may pass therethrough. Pole pieces 8 are made of metallic
or increasing the turns of the upper bobbin has the positive and magnetizable material and are conveniently placed or
effect of lowering the impedance of the pickup at higher threaded into corresponding holes in base plate 12. Pole
frequencies, which will enhance the amplitude and quality pieces 8 are positioned below the strings 14 of the musical
of the pickup’s treble response. By employing a heavier instrument and may be individually adjusted (by threading
gauge of wire in the lower bobbin than in the upper bobbin, 40 more or less into the base plate 12) to vary the spacing
DC resistance of the pickup is further reduced. between pole pieces 8 and StringS 14.
If a further increase in inductance were required for a Bobbins 24 and 26 each have a body made of non
Specific application, additional ferromagnetic material might electrically conductive, non-magnetic and non-magnetizable
be positioned between the magnets of the upper bobbin, and material. Pole pieces 8 pass through holes in the bodies of
properly balanced by the correct gauge and number of turns 45 bobbins 24 and 26 before entering holes in strips 18 and 20
of wire on the lower bobbin. This configuration serves to and base plate 12.
maintain the hum-cancelling capabilities of the pickup. Coils 28 and 30 are wound about the bodies of bobbins 24
In all the embodiments, it is preferable for the pole pieces and 26, respectively. The coils may be formed of 5,000 turns
to be aligned with the Strings. of 42 gauge insulated copper wire, of 10,000 turns of 50
50 gauge wire, or of Some other combination known to those in
BRIEF DESCRIPTION OF THE DRAWING the art. The coils also may use different gauges of wire, as
Further objects, features and advantages of the invention disclosed in U.S. Pat. No. 4,501,185.
will become apparent from the following detailed descrip In accordance with the invention, ferromagnetic material,
tion taken in conjunction with the accompanying figures in preferably in the form of cylinders or plugs 5, are disposed
which: 55 in the body of the bobbins 24 and 26 between the pole pieces
FIG. 1 is a top view of a pickup in accordance with a 8. In a second embodiment of the present invention, shown
preferred embodiment of the invention; in FIG. 3, strips 7 of ferromagnetic material are positioned
FIG. 2 is a perspective view of the pickup of FIG. 1; between the bobbins (24, 26) and the base plate 12 and are
FIG. 3 is a perspective view of a pickup in accordance adjoining the outside edges of and in the same plane as
60 metallic strips 18 and/or 20. These strips 7 may be posi
with a Second embodiment of the invention; and tioned adjoining only one of the metallic Strip edges (18, 20)
FIG. 4 is a perspective view of a pickup in accordance or may be disposed directly alongside magnet 16 in a
with a third embodiment of the invention. configuration without metallic Strips. The additional ferro
FIG. 5 is a perspective view of a pickup in accordance magnetic material increases the inductance of the pickup
with a fourth embodiment of the invention. 65 without increasing the DC resistance. In a single coil pickup
Throughout the figures, the same reference numerals and (not illustrated), the plugs 5 and/or strips 7 would be
characters, unless otherwise Stated, are used to denote like similarly disposed as they are in either of bobbins 24 or 26.
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In the embodiment of the hum-cancelling pickup of U.S. 2. The electromagnetic pickup of claim 1 wherein Said
Pat. No. 4,501,185, herein incorporated by reference, a first magnetic device comprises a plurality of pole pieces
hum-cancelling bobbin has a gauge of wire different from a extended through Said holes.
second hum-cancelling bobbin such that the second bobbin 3. An electromagnetic pickup device having an induc
has a resonant frequency lower than the first bobbin. In this tance for a Stringed musical instrument having a plurality of
embodiment, the ferromagnetic plugs 5 or Strips 7 are, ferromagnetic Strings, comprising:
preferably, applied to the bobbin having the lower resonant first and Second bobbins, each having a body mountable
frequency to further emphasize and accentuate the differing on Said instrument proximate and below Said Strings
frequencies.
FIG. 4 illustrates another embodiment of the present and a coil wrapped around Said body, at least one of
invention. As described in U.S. Pat. No. 4,442,749, herein Said bodies having a plurality of holes therethrough;
incorporated by reference, bobbins 44 and 46 are positioned a magnetic device for generating a magnetic field around
in a vertical, rather than horizontal, configuration of a pickup said bobbins;
40. While bobbin 44 senses the vibration of the strings, a plurality of pole pieces extended through Said holes, and
bobbin 46 functions passively to cancel hum. Preferably, the 15 ferromagnetic material Selectively positioned within at
bobbins are separated by a plate 42 which is constructed least one of Said bodies to increase Said inductance
from a Single piece of ferromagnetic material. Plate 42 without causing a corresponding increase in Said pick
creates a focused magnetic field immediately above the up’s DC resistance and to effectively cancel externally
pickup to increase the Signal weakened by the Vertical generated hum and noise.
configuration. In addition, plate 42 increases the inductance 4. The electromagnetic pickup of claim 3 wherein Said
of pickup 40. By increasing or decreasing the thickness of ferromagnetic material is cylindrically shaped.
plate 42 and using materials of various permeabilities, the 5. The electromagnetic pickup of claim 3 wherein Said
inductance of pickup 40 can be increased or decreased to pole pieces are aligned with Said Strings.
control the tone produced. 6. The electromagnetic pickup of claim 3 wherein Said
In FIG. 4, holes 48 in bobbin 44 receive pole pieces 50 25 magnetic device includes at least one permanent magnet
and ferromagnetic material 45 is disposed between holes 48 having a first edge and a Second edge of opposite polarities,
in passive bobbin 46, according to one embodiment of the Said magnet positioned in close proximity to Said at least one
invention, to increase its inductance. Alternatively, ferro bobbin to create Said magnetic field there around.
magnetic material 45 may be disposed either within or 7. The electromagnetic pickup of claim 6 wherein Said
between holes 48 of bobbin 46. Bobbin 46 may also be first edge of Said magnet constitutes a magnetic north pole
provided without holes in its body (not shown), in which and Said Second edge of Said magnet constitutes a magnetic
case ferromagnetic material may be positioned anywhere South pole.
within its body to achieve the objectives of the invention. In 8. An electromagnetic pickup device having an induc
an embodiment where both plate 42 and bobbin 46 have tance for a Stringed musical instrument having a plurality of
holes to receive pole pieces 50 which extend only partially 35 ferromagnetic Strings, comprising:
into bobbin 46, additional ferromagnetic material may also first and Second hum-cancelling bobbins, each having a
be inserted in holes 48 of bobbin 46 below pole pieces 50. body mountable on Said instrument proximate and
Ferromagnetic material 50 may also be positioned between below Said Strings and a coil wrapped around Said body,
the holes 48 of the upper bobbin 44, as shown in FIG. 5. at least one of Said bodies having a plurality of holes
AS described above, the ferromagnetic material may also 40 therethrough;
take the form of strips 52 positioned beneath the body of a magnetic device for generating a magnetic field around
bobbin 46 adjoining the outside edges 54 of metallic strips.
Preferably, the number of wire turns in the coil of bobbin 46 said bobbins;
is reduced while maintaining or increasing the number of a plurality of pole pieces extended through at least a
wire turns in the coil of bobbin 44. Finally, the gauge of wire 45
plurality of Said holes, and
on the coil of bobbin 46 is preferably heavier than that on the ferromagnetic material positioned between Said holes of
coil of bobbin 44. Said body to increase Said inductance, wherein Said first
Other modifications of the invention will occur to those hum-cancelling bobbin has a gauge of wire different
skilled in the art Such as placing the additional ferromagnetic from Said Second hum-cancelling bobbin Such that Said
material in different locations, e.g., between two or more 50 Second hum-cancelling bobbin has a resonant fre
bobbins, and it is intended that the scope of the invention be quency lower than Said first hum-cancelling bobbin and
limited only as Set forth in the appended claims. wherein Said ferromagnetic material is positioned
We claim: within Said body of Said Second hum-cancelling bob
1. An electromagnetic pickup device having an induc bin.
tance for a Stringed musical instrument having a plurality of 55
9. An electromagnetic pickup device having an induc
ferromagnetic Strings, comprising: tance for a Stringed musical instrument having a plurality of
first and Second bobbins, each having a body mountable ferromagnetic Strings, comprising:
on Said instrument proximate and below Said Strings first and Second bobbins, each having a body mountable
and a coil wrapped around Said body, at least one of on Said instrument proximate and below Said Strings
Said bodies having a plurality of holes therethrough; 60 and a coil wrapped around Said body;
a magnetic device for generating a magnetic field around a magnetic device for generating a magnetic field around
said bobbins; and said bobbins; and
ferromagnetic material Selectively positioned within at ferromagnetic material Selectively positioned between
least one of Said bodies to increase Said inductance Said bodies and Said musical instrument to increase Said
without causing a corresponding increase in Said pick 65 inductance without causing a corresponding increase in
up’s DC resistance and to effectively cancel externally Said pickup’s DC resistance and to effectively cancel
generated hum and noise. externally generated hum and noise.
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10. The electromagnetic pickup of claim 9 wherein said and an lower bobbin coil of wire wrapped around said
body has one or more holes therethrough and Said magnetic lower bobbin body, said bodies mountable on said
device comprises one or more pole pieces extended through instrument proximate and below Said Strings, Said coils
Said one or more holes. having axes perpendicular to Said Strings,
11. An electromagnetic pickup device having an induc a magnetic device for generating a magnetic field around
tance for a Stringed musical instrument having a plurality of said bobbins; and
ferromagnetic Strings, comprising: ferromagnetic material positioned within Said lower bob
first and Second bobbins, each having a body mountable bin body to increase Said inductance.
on Said instrument proximate and below Said Strings 20. The electromagnetic pickup of claim 19 wherein said
and coil wrapped around Said body; at least one of Said bodies has a plurality of holes there
a magnetic device for generating a magnetic field around through and Said magnetic device comprises a plurality of
said bobbins: and pole pieces extended through said holes.
ferromagnetic material Selectively positioned within Said 21. An electromagnetic pickup device having an induc
body to increase Said inductance without causing a tance for a Stringed musical instrument having a plurality of
corresponding increase in Said pickup’s DC resistance 15 ferromagnetic Strings, comprising:
and to effectively cancel externally generated hum and an upper bobbin having an upper bobbin body and an
noise. upper bobbin coil of wire wrapped around Said upper
12. The electromagnetic pickup of claim 11 wherein Said bobbin body;
body has one or more holes therethrough and Said magnetic a lower bobbin positioned below and coaxial to Said upper
device comprises one or more pole pieces extended through bobbin, said lower bobbin having a lower bobbin body
Said one or more holes. and an lower bobbin coil of wire wrapped around said
13. An electromagnetic pickup device having an induc lower bobbin body, said bodies mountable on said
tance for a Stringed musical instrument having a plurality of instrument proximate and below Said Strings, Said coils
ferromagnetic Strings, comprising: 25
having axes perpendicular to Said Strings and at least
first and Second bobbins, each having a body mountable one of Said bodies having a plurality of holes there
on Said instrument proximate and below Said Strings through;
and a coil wrapped around Said body, at least one, of a magnetic device for generating a magnetic field around
Said bodies having one or more holes therethrough; said bobbins;
a magnetic device for generating a magnetic field around a plurality of pole pieces extended through Said holes, and
said bobbins; ferromagnetic material positioned within Said lower bob
one or more pole pieces extended through Said one or bin body to increase Said inductance.
more holes, and 22. The electromagnetic pickup of claim 21 wherein said
ferromagnetic material Selectively positioned between ferromagnetic material is positioned between said holes of
Said bodies and Said musical instrument to increase Said 35 said lower bobbin body.
inductance without causing a corresponding increase in 23. The electromagnetic pickup of claim 21 wherein Said
Said pickup’s DC resistance and to effectively cancel ferromagnetic material is further positioned between said
externally generated hum and noise. holes of said upper bobbin body.
14. The electromagnetic pickup of claim 13 wherein Said 24. The electromagnetic pickup of claim 22 or 23 wherein
pole pieces are aligned with Said Strings. 40 Said ferromagnetic material is cylindrically shaped.
15. The electromagnetic pickup of claim 13 wherein said 25. The electromagnetic pickup of claim 21 wherein Said
magnetic device includes at least one permanent magnet pole pieces are aligned with Said Strings.
having a first edge and a Second edge of opposite polarities, 26. The electromagnetic pickup of claim 21 further com
Said magnet positioned in close proximity to Said at least one prising an integral plate of magnetic material having a base
bobbin to create Said magnetic field there around. 45 disposed between Said bobbins perpendicular to Said coil
16. The electromagnetic pickup of claim 15 wherein said axes and two Side walls extending upwardly and perpen
first edge of Said magnet constitutes a magnetic north pole dicularly from said base about said upper bobbin.
and Said Second edge of Said magnet constitutes a magnetic 27. The electromagnetic pickup of claim 21 wherein Said
South pole. magnetic device includes at least one permanent magnet
17. The electromagnetic pickup of claim 16 wherein said 50 having a first edge and a Second edge of opposite polarities,
ferromagnetic material is shaped in the form of one or more Said magnet positioned in close proximity to Said lower
Strips adjoining at least one edge of Said magnet. bobbin to create said magnetic field around said bobbins.
18. The electromagnetic pickup of claim 16 wherein said 28. The electromagnetic pickup of claim 27 wherein said
magnetic device further comprises at least one metallic Strip first edge of Said magnet constitutes a magnetic north pole
attached to one or more of Said edges of Said magnet, Said 55 and Said Second edge of Said magnet constitutes a magnetic
at least one metallic Strip dimensioned to receive one or South pole.
more of Said pole pieces and wherein Said ferromagnetic 29. An electromagnetic pickup device having an induc
material is shaped in the form of one or more Strips adjoining tance for a Stringed musical instrument have a plurality of
an outer edge of Said at least one metallic Strip. ferromagnetic Strings, comprising:
19. An electromagnetic pickup device having an induc 60 an upper bobbin having an upper bobbin body and an
tance for a Stringed musical instrument having a plurality of upper bobbin coil of wire wrapped around Said upper
ferromagnetic Strings, comprising: bobbin body;
an upper bobbin having an upper bobbin body and an a lower bobbin positioned below the coaxial to said upper
upper bobbin coil of wire wrapped around Said upper bobbin, said lower bobbin having a lower bobbin body
bobbin body; 65 and an lower bobbin coil of wire wrapped around said
a lower bobbin positioned below and coaxial to Said upper lower bobbin body, said bodies mountable on said
bobbin, said lower bobbin having a lower bobbin body instrument proximate and below Said Strings, Said coils
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having axes perpendicular to Said Strings and at least ferromagnetic material positioned within at least one of
one of Said bodies having a plurality of holes there Said bodies to increase Said inductance.
through; 34. The electromagnetic pickup of claim 33 wherein said
a magnetic device for generating a magnetic field around at least one of Said bodies has a plurality of holes there
said bobbins; through and Said magnetic device comprises a plurality of
a plurality of pole pieces extended through said holes, and pole pieces extended through said holes.
35. An electromagnetic pickup device having an induc
ferromagnetic material positioned within Said lower bob tance for a Stringed musical instrument having a plurality of
bin body to increase Said inductance, wherein Said ferromagnetic Strings, comprising:
upper bobbin coil has more turns of wire than said an upper bobbin having an upper bobbin body and an
lower bobbin coil. upper bobbin coil of wire wrapped around Said upper
30. An electromagnetic pickup device having an induc bobbin body;
tance for a Stringed musical instrument have a plurality of a lower bobbin positioned below and coaxial to Said upper
ferromagnetic Strings, comprising: bobbin, said lower bobbin having a lower bobbin body
an upper bobbin having an upper bobbin body and an 15 and an lower bobbin coil of wire wrapped around said
upper bobbin coil of wire wrapped around Said upper lower bobbin body, said bodies mountable on said
bobbin body; instrument proximate and below Said Strings, Said coils
a lower bobbin positioned below and coaxial to Said upper having axes perpendicular to Said Strings and at least
bobbin, said lower bobbin having a lower bobbin body one of Said bodies having a plurality of holes there
and an lower bobbin coil of wire wrapped around said through;
lower bobbin body, said bodies mountable on said a magnetic device for generating a magnetic field around
instrument proximate and below Said Strings, Said coils said bobbins;
having axes perpendicular to Said Strings and at least a plurality of pole pieces extended through Said holes, and
one of Said bodies having a plurality of holes there ferromagnetic material positioned beneath Said lower
through; 25 bobbin body to increase said inductance.
a magnetic device for generating a magnetic field around 36. The electromagnetic pickup of claim 35 wherein said
said bobbins; pole pieces are aligned with Said Strings.
a plurality of pole pieces extended through said holes, and 37. The electromagnetic pickup of claim 35 further com
ferromagnetic material positioned within Said lower body prising an integral plate of magnetic material having a base
to increase Said inductance, wherein Said wire of Said disposed between Said bobbins perpendicular to Said coil
lower bobbin coil has a heavier gauge than Said wire of axes and two Side walls extending upwardly and perpen
said upper bobbin coil. dicularly from said base about said upper bobbin.
31. An electromagnetic pickup device having an induc 38. The electromagnetic pickup of claim 35 wherein said
tance for a Stringed musical instrument having a plurality of magnetic device includes at least one permanent magnet
ferromagnetic Strings, comprising: 35 having a first edge and a Second edge of opposite polarities,
an upper bobbin having an upper bobbin body and an Said magnet positioned in close proximity to Said lower
upper bobbin coil of wire wrapped around Said upper bobbin to create said magnetic field around said bobbins.
bobbin body; 39. The electromagnetic pickup of claim 38 wherein said
first edge of Said magnet constitutes a magnetic north pole
a lower bobbin positioned below and coaxial to Said upper 40 and Said Second edge of Said magnet constitutes a magnetic
bobbin, said lower bobbin having a lower bobbin body South pole.
and an lower bobbin coil of wire wrapped around said 40. The electromagnetic pickup of claim 39 wherein said
lower bobbin body, said bodies mountable on said ferromagnetic material is shaped in the form of one or more
instrument proximate and below Said Strings, Said coils Strips adjoining to at least one edge of Said magnet.
having axes perpendicular to Said Strings, 45 41. The electromagnetic pickup of claim 38 wherein said
a magnetic device for generating a magnetic field around magnetic device further comprises at least one metallic Strip
said bobbins; and attached to one or more of Said edges of Said magnet, Said
ferromagnetic material positioned beneath Said lower at least one magnetic Strip dimensioned to receive one or
bobbin body to increase said inductance. more of Said pole pieces and wherein Said ferromagnetic
32. The electromagnetic pickup of claim 31 wherein said 50 material is shaped in the form of one or more Strips adjoining
at least one of Said bodies has a plurality of holes there to an outer edge of Said at least one metallic Strip.
through and Said magnetic device comprises a plurality of 42. An electromagnetic pickup device having an induc
pole pieces extended through said holes. tance for a Stringed musical instrument having a plurality of
33. An electromagnetic pickup device having an induc ferromagnetic Strings, comprising: first and Second bobbins,
tance for a Stringed musical instrument having a plurality of 55 each having a body mountable on Said instrument proximate
ferromagnetic Strings, comprising: and below Said Strings and a coil of wire wrapped around
an upper bobbin having an upper bobbin body and an said body, said coil of said first bobbin having more turns of
upper bobbin coil of wire wrapped around Said upper wire than Said coil of Said Second bobbin, and ferromagnetic
bobbin body; material added to Said Second bobbin to increase Said
a lower bobbin positioned below and coaxial to Said upper 60 inductance and to effectively cancel externally generated
bobbin, said lower bobbin having a lower bobbin body hum and noise.
and an lower bobbin coil of wire wrapped around said 43. A method of making an electromagnetic pickup device
lower bobbin body, said bodies mountable on said having an inductance for a Stringed musical instrument
instrument proximate and below Said Strings, Said coils having a plurality of ferromagnetic Strings, comprising the
having axes perpendicular to Said Strings, 65 following Steps:
a magnetic device for generating a magnetic field around providing two bobbins each having a body mountable on
said bobbins; and Said instrument proximate and below Said Strings,
 5,908,998
11 12
providing two coils, one wrapped around one of Said 46. A method of making an electromagnetic pickup device
bodies, and the other coil wrapped around the other of having an inductance for a Stringed musical instrument
Said bodies, Said coils having a different number of having a plurality of ferromagnetic Strings, comprising the
turns of wire; following Steps:
adding ferromagnetic material to that body having the coil 5
providing two bobbins each having a body mountable on
with fewer turns to increase Said inductance and to
effectively cancel externally generated hum and noise. Said instrument proximate and below Said Strings,
44. The method of claim 43 wherein said coil with fewer providing two coils, one wrapped around one of Said
turns is provided below Said coil with greater turns. bodies, and the other coil wrapped around the other of
45. An electromagnetic pickup device having an induc Said bodies, Said coils having different gauges of wire;
tance for a Stringed musical instrument having a plurality of adding ferromagnetic material to that body having the coil
ferromagnetic Strings, comprising: first and Second bobbins,
each having a body mountable on Said instrument proximate with the heavier gauge of wire to increase Said induc
and below Said Strings and a coil of wire wrapped around tance and to effectively cancel externally generated
said body, said coil of said first bobbin having a lighter 15 hum and noise.
gauge of wire than Said coil of Said Second bobbin, and 47. The method of claim 46 wherein said coil with heavier
ferromagnetic material added to Said Second bobbin to gauge is provided below Said coil with lighter gauge.
increase Said inductance and to effectively cancel externally
generated hum and noise. k k k k k
 UNITED STATES PATENT AND TRADEMARK OFFICE
CERTIFICATE OF CORRECTION
1 of 3
PATENT NO. : 5,908,998 Page l o
DATED June 1, 1999
INVENTOR(S) :
Steven L. Blucher et all
It is certified that error appears in the above-identified patent and that said Letters Patent is hereby
Corrected as shown below:

IN THE CLAMS:

Column 7, line 27, claim 13: "one, of" should read -- one of -.
Column 8, line 7, claim 19: "material positioned" should read - material selectively
positioned -.
Column 8, line 8, claim 19: "inductance." should read - inductance without causing
a Corresponding increase in said pickup's DC resistance and to effectively cancel externally
generated hum and noise. --.
Column 8, line 30, claim 21: "material positioned" should read - material selectively
positioned --.
 UNITED STATES PATENT ANDTRADEMARK OFFICE
CERTFCATE OF CORRECTION
PATENT NO. : 5,908,998 Page 2 of 3
DATED
June 1, 1999
INVENTOR(S) : Steven L. Blucher et all
it is certified that error appears in the above-identified patent and that said Letters Patent is hereby
Corrected as shown below:

Column 8, line 31, claim 21: "inductance." should read - inductance without
causing a corresponding increase in said pickup's DC resistance and to effectively cancel
externally generated hum and noise. --.
Column 8, line 63, claim 29: "the" should read - and --.
Column 9, line 47, claim 31: "material positioned" should read - material selectively
positioned -.
Column 9, line 48, claim 31: "inductance." should read - inductance without
causing a corresponding increase in said pickup's DC resistance and to effectively cancel
externally generated hum and noise. --.
Column 10, line 1, claim 33: "material positioned" should read -- material selectively
positioned -.
Column 10, line 2, claim 33: "inductance." should read - inductance without
causing a corresponding increase in said pickup's DC resistance and to effectively cancel
externally generated hum and noise. --.
 UNITED STATES PATENT ANDTRADEMARK OFFICE
CERTIFICATE OF CORRECTION
PATENT NO. : 5,908,998 Page 3 of 3
DATED June 1, 1999
INVENTOR(S) :
(S) Steven L. Blucher
It is certified that error appears in the above-identified patent and that said Letters Patent is hereby
Corrected as shown below:

Column 10, line 23: "material positioned" should read - material selectively
positioned -.
Column 10, line 24, claim 35: "inductance." should read - inductance without
causing a corresponding increase in said pickup's DC resistance and to effectively cancel
externally generated hum and noise. --.

Signed and Sealed this

Sixth Day of February, 2001

272-ya
Q. TODD DICKNSON
Attesting Officer Director of Parents and Trademarks