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

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.

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.