Humbucker
The "humbucking coil" was invented in 1934 by Electro-Voice, an American professional audio company based in South Bend, Indiana, that Al Kahn and Lou Burroughs incorporated in 1930 for the purpose of manufacturing portable public address equipment, including microphones and loudspeakers.
[1] The twin coiled guitar pickup invented by Arnold Lesti in 1935 is arranged as a humbucker, and the patent USRE20070[2] describes the noise cancellation and current summation principles of such a design.
Knoblaugh invented a pickup for stringed instruments involving two stacked coils described in U.S. patent 2,119,584.
The 1939 April edition of Radio Craft Magazine[3] shows how to construct a guitar pickup made with two identical coils wrapped around self-magnetized iron cores, where one is then flipped over to create a reverse-wound, reverse-polarity, humbucking orientation.
To overcome the hum problem for guitars, a humbucking pickup was invented by Seth Lover of Gibson under instruction of then-president Ted McCarty.
[4][5] A successful early humbucking pickup was the type which is nowadays known as the "PAF" (literally "Patent Applied For") invented by Seth Lover in 1955.
Rickenbacker offered dual coil pickups arranged in a humbucking pattern beginning in late 1953 but dropped the design in 1954 due to the perceived distorted sound, which had stronger mid-range presence.
However, wire coils also make excellent antennas and are therefore sensitive to electromagnetic interference caused by alternating magnetic fields from mains wiring (mains hum) and electrical appliances like transformers, motors, and computer screens, especially older CRT monitors.
The technique has something in common with what electrical engineers call "common-mode rejection", and is also found in the balanced lines used in audio equipment.
Installing full/double-sized humbuckers in this type of guitar requires additional routing of the woodwork, and/or cutting of the pickguard if the instrument has one.
Another design known as the rail humbucker features a single magnetic component spanning across the entire string width of the instrument.
The electrical circuit of the pickup is reduced to that of a true single coil so there is no hum canceling effect.
This configuration is often referred to as a "split coil" pickup, which should not be confused with the possibility of "coil-splitting" a regular humbucker, as discussed above.
Both coils see nearly identical extraneous electromagnetic disturbances, and since they are wired in humbucking fashion, can effectively cancel them.
However, the majority of the sound signal of any single note will mostly be generated by just one of the coils, so that output level and tonal qualities are much closer to a regular single-coil pickup.
The resulting "P-Style" pickup is usually regarded as the main ingredient of the "P-Bass" sound, and many variants on the design are offered by many manufacturers.
These were of the stacked humbucker design, where the lower pickup coil functions solely to cancel hum.
With its much-increased output compared to humbuckers installed in guitars of the time, it became an instant favourite of many hard-rock guitarists, and it remains a popular choice for a pickup upgrade decades later.
