Electromagnetic pickup for a stringed musical instrument having ferromagnetic strings and method

• US 4,524,667 A
• Filed: 08/15/1983
• Issued: 06/25/1985
• Est. Priority Date: 08/15/1983
• Status: Expired due to Fees

• Current Assignee: Seymour Duncan
• Original Assignee: Seymour Duncan
• Inventors: Duncan, Seymour
• Primary Examiner(s): Isen, Forester W.
• Application Number:
  US06/523,067
• Time in Patent Office: 680 Days
• Field of Search: 84/1.16, 84/1.14, 84/1.15
• US Class Current: 84/728
• CPC Class Codes: G10H 2220/511 Stacked, i.e. one coil on top of the other
• CPC Class Codes: G10H 3/181 Details of pick-up assemblies

Abstract

An electromagnetic pickup adapted for use with a multistringed musical instrument having strings formed of a ferromagnetic material having a first wire coil wound in a first direction in an elongated oval shape wherein the first coil has a geometrical distance along its elongated axis which exceeds the distance between the outermost strings wherein the first coil includes an opening which extends through the interior thereof, a second wire coil wound in a second direction and in an elongated oval shape, the geometrical dimensions of which are substantially equal to that of the first coil and wherein the second coil includes a second opening which extends to the interior thereof, and wherein the second coil is positioned in a spaced opposed aligned relationship with the first coil with the first opening in axial alignment with the second opening forming a coil stack assembly having a hollowed-out central cavity, a permanent magnet assembly which is positioned in the hollowed-out central cavity with one pole positioned in a magnetic coupling relationship with the strings of the multistringed instrument and with the other pole positioned so as to be remote from the string and a circuit for electrically connecting the first coil and the second coil in either a selected dual- or single-coil configuration wherein the coil stack assembly applies a magnetic field across the strings which is intercepted by the vibrating strings to produce an electrical signal is shown. A method for utilizing an electromagnetic pickup is shown.

Claims

1. An electromagntic pickup adapted for use with a multistringed musical instrument having strings formed of a ferromagnetic material comprising

a first coil having wire wound in a first direction and in an elongated oval shape having a major and minor axis, said first coil having a first geometrical distance along the major axis which exceeds the distance between the outermost strings of a multistringed musical instrument adapted to use the electromagnetic pickup and a second geometrical distance along the minor axis which is substantially less than that along the major axis, said first coil including means defining a first opening which extends through the interior thereof;

a second coil having wire wound in a second direction and in an elongated oval shape having major and minor axes and the geometrical dimensions of which are substantially equal to that of said first coil, said second coil including means defining a second opening which extends through the interior thereof, said second coil being positioned in a spaced opposed aligned relationship with said first coil with the first opening of said first coil in axial alignment with the second opening of said second coil positioning the major axis of said first coil in a spaced parallel aligned relationship with the major axis of said second coil forming a coil stack assembly having a hollowed-out central cavity defined by said first opening communicating with said second opening;

a permanent magnet means having a north magnetic pole and a south magnetic pole positioned in said hollowed-out central cavity with one of said north magnetic pole and south magnetic pole positioned therein so as to be adapted to be adjacent to and to magnetically couple with a string of a said multistringed musical instrument and with the other of said north magnetic pole and south magnetic pole positioned therein so as to be adapted to be remote to a string of a said multistringed musical instrument;

said permanent magnetic means further including

a plurality of spaced, cylindrically shaped permanent magnet elements having an axial length which enables the permanent magnet elements to be located within the hollowed-out central cavity and a diameter which is less than the second geometrical dimension of the minor axis of said first opening and said second opening and wherein at least two of the cylindrically shaped permanent magnet members have different axial lengths, said cylindrically shaped permanent magnetic elements being positioned in said hollowed-out central cavity with the axes thereof in spaced parallel relationship to each other; and

coil connecting means operatively coupled to said first coil and said second coil to selectively connect the same in at least one of series opposition, parallel opposition and selected single coil configuration, said coil connecting means and coil stack assembly being adapted to produce a magnetic field which traverses a path from the hollowed-out central cavity of the coil stack assembly, through said permanent magnet means to a said string of a said multistringed musical instrument formed of ferromagnetic material defining a magnetic flux path, the reluctance of which is varied in response to the vibration of a said string of a said multistringed musical instrument which is adapted to vary the magnetic field inducing a voltage into said coils which varies in amplitude and frequency.

2. The electromagnetic pickup of claim 1 wherein the end of each cylindrically shaped permanent magnet means is adapted to be positioned adjacent a string is substantially coplanar with the other ends of each of the cylindrically shaped magnet members which are adapted to likewise be positioned adjacent to the other strings, all of which are adapted to define a gap having a selected distance and wherein the opposite ends of each of the cylindrically shaped magnet members are in a staggered relationship.

3. The electromagnetic pickup of claim 1 wherein said first coil and said second coil are wound in the same direction.

4. The electromagnetic pickup of claim 1 wherein the cylindrically shaped permanent magnet elements are assembled in pairs with a selected distance between adjacent pairs.

5. The electromagnetic pickup of claim 1 wherein each cylindrically shaped permanent magnet element has a selected axial length.

6. The electromagnetic pickup of claim 1 wherein said first coil and said second coil are wound in opposite directions.

7. An electromagnetic guitar pickup comprising

a substantially planar support member;

a first coil form formed of nonmagnetic material having elongated oval shape and including means for defining a first wire receiving channel around the periphery thereof, said first coil form having a first geometrical dimension along the major axis of the elongated oval shape which exceeds the distance between the outermost strings of a said guitar adapted to use the electromagnetic pickup, said coil form including means for defining a first opening which extends through the interior thereof;

a first wire coil wound in a first direction in the first wire-receiving channel of said first coil form;

a second coil form formed of a nonmagnetic material and having an elongated oval shape and including means for defining a second wire receiving channel around the periphery thereof, said second coil form having geometrical dimension along its major and minor axes which are substantially equal to that of said first coil form, said second coil form including means for defining a second opening which extends through the interior thereof, said second coil form being positioned in an aligned, spaced opposed relationship with said first coil form with the first opening of said coil form in axial alignment with the second opening of said coil form positioning the major axis of said first coil in a spaced parallel aligned relationship with the major axis of said second coil form forming a stacking relationship with said first coil form having a hollowed-out central cavity extending therethrough defined by said first opening communicating with said second opening;

a second coil form with wire wound in a second direction in the second wire-receiving channel of said second coil form;

means for operatively selectively connecting the first wire coil of said first coil form with said second wire coil;

a permanent magnet means having a magnetic north pole and a magnetic south pole positioned in said hollowed-out central cavity with one of said magnetic north pole and said magnetic south pole being adapted to be positioned in the hollowed-out central cavity such that when the electromagnetic pickup is positioned on a guitar at least one of said magnetic north pole and said magnetic south pole are adapted to magnetically couple the strings;

said permanent magnetic means further including

a plurality of spaced, cylindrically shaped permanent magnet elements having axial lengths which enable the permanent magnet elements to be located within the hollowed-out central cavity and a diameter which is less than the second geometrical dimension of the minor axis of said first opening and said second opening and wherein at least two of the cylindrical shaped permanent magnet members have different axial lengths, said cylindrically shaped permanent magnetic elements being positioned in said hollowed-out central cavity with the axes thereof in spaced parallel relationship to each other; and

means operatively coupled to said first wire coil and said second wire coil for selectively connecting same in at least one of a series opposition, parallel opposition and selected single coil configuration.

8. A method for electromagnetically picking up vibrations from ferromagnetic strings on a multistringed musical instrument comprising the steps of:

positioning at a selected location and gap distance relative to strings of a multistringed musical instrument a coil stack assembly having a first coil having a wire wound in a first direction therearound in spaced, aligned relationship with a second coil having wire wound in a second direction therearound and an elongated oval shaped hollowed-out central area having a permanent magnet means located therein with at least one of a north magnetic pole and a south magnetic pole located near the strings, said permanent magnet means having a plurality of spaced, cylindrically shaped permanent magnet elements wherein at least two of the cylindrically shaped permanent magnet elements have different axial lengths;

electrically connecting with an electrical connecting means said first coil and said second coil into at least one of a series opposition, parallel opposition and selected single-coil configuration;

vibrating at least one of said ferromagnetic strings to vary the reluctance of the air gap and induce a voltage in at least one of said first coil and second coil which represents the vibrations of a second ferromagnetic string; and

sensing the change in amplitude and frequency of said voltage to produce an output signal representative of the vibrations of a said string.

9. The method of claim 8 further comprising the step of amplifying the output signal.

10. An electrical pickup for a stringed musical instrument having ferromagnetic strings, said pickup comprising

a pair of axially spaced, elongated coils arranged to have their elongated axis extend substantially parallel to the width of the strings on an instrument and defining an elongated passageway through each coil which communicates with each other;

a plurality of spaced, cylindrical shaped elongated permanent magnet members, at least two of which have different lengths along their longitudinal axis and disposed in said elongated passageway with each axis of each permanent magnet member extending substantially through each coil and positioned with one end of each of said elongated permanent magnets being adapted to be positioned in a predetermined spaced relationship from a selected one of said ferromagnetic strings.

11. The electrical pickup of claim 10 in which said coils are connected in a series, opposing relationship.

12. The electrical pickup of claim 10 in which the coils are respectively disposed on a pair of bobbins wherein said bobbins, coils and pole pieces are formed into an integral assembly.

13. An electrical pickup for a stringed musical instrument having ferromagnetic strings, said pickup comprising

a pair of elongated spaced coils having a center cavity and wherein the coils are connected in series operation;

a pair of spaced elongated permanent magnet members, at least two of which have different lengths along their longitudinal axis and disposed in the center cavity with each axis of each permanent magnet member extending substantially through each coil and positioned with one end of each of said permanent magnets positioned in a spaced relationship from a selected one of said ferromagnetic strings.