Humbucker
From Wikipedia, the free encyclopedia
A conventional humbucker (or Humbucking pickup) is a type of electric guitar pickup that uses two coils, both generating string signal. Humbuckers have high output since both coils are in series and because the magnetic circuit is low loss. Since the two coils are of reversed polarity and reverse-wound and connected in series, noise and interference is essentially 'canceled out' through a differential amplifier. They get their name because they cancel out a large proportion of the hum (they "buck the hum").
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[edit] Invention
All magnetic pickups are sensitive to electronic noise emitted from electrical appliances that are powered by a 50Hz or 60Hz mains supply. This noise is called mains hum and comes from from mains wiring in buildings, electric motors, transformers as well as computer screens. This noise is picked up by magnetic transducers (pickups) and is quite audible, and sounds like a constant hum or buzz, with a pitch of 50 or 60 Hz, depending on locale.
The guitar's required signal is caused by the interaction of the guitar strings with a permanent magnet in the pickup, while the electric field from the mains is independent of the magnet. Thus, reversing the magnet reverses the signal, while the undesired hum is not reversed. To eliminate the hum, what were essentially two single-coils with opposing magnetic directions were placed next to each other and wired in series, with one reversed. A variant winds the second coil with opposite handedness.
This first "humbucker" or humbucking pickup was the so-called PAF invented by Seth Lover, a Gibson employee, in the 1950s. Because of this, and because of its use on the Gibson Les Paul guitar, the humbucker is strongly associated with Gibson, although humbuckers have been used in many different guitar designs by many different manufacturers. Humbuckers are also known as dual-coil, double-coil, or hum-canceling pickups. 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. The Gibson Les Paul was the first guitar to use humbuckers in substantial production, but since then, even Fender Stratocasters and Telecasters, which commonly have single-coil pickups, sometimes now come factory-equipped with humbuckers.
[edit] Sound
Using two coils also changes the tone of the pickup. The humbucker pickup produces a "warm" and "fat" tone that has been popularly associated with Les Pauls and SGs, in contrast to the "bright" or "clear" tone of the single coil pickups that are typically used on Fender guitars such as the Stratocaster and Telecaster.
It is a common misconception that because the coils are at slightly different positions along the string some of the higher-frequency harmonics are diminished or cancelled out, thus producing this warmer sound. The main reason humbuckers sound different is because two coils resonate at different frequencies causing a broad resonant peak in frequency response, a characteristic of the original Gibson humbuckers, and because any two pickups wired in series will attenuate some of the higher frequencies due to the summed impedance.
Usually, those who prefer the brighter sound of single-coil pickups had to simply live with the extra hum and buzz in order to get the tone they prefer, although technologies designed to preserve the tones exist.
[edit] Other noise reduction attempts
Inventors have tried many other approaches to reducing 50/60Hz noise in guitar pickups, such as:
- Stacking the two coils of a humbucker in a vertical arrangement so it can fit in a single-coil size, producing a stacked humbucker;
- Since 1971, a Fender Wide Range humbucker;
- Since 1985, a hum-screening technique used by Lace Sensor pickups;
- Since 1996, a differential coil technology, basically a new configuration of stacked humbuckers by Kinman Guitar Electrix, where the lower pickup coil functions solely as a noise sensing coil, while only the upper pickup coil is able to sense the string vibrations
However, the original humbucker remains the most common noise-reducing pickup design.
Many modern single-coil equipped guitars today are wired with the middle pickup in reverse, and with a 5-way switch allow the player two different positions in which the single-coils work together in series and act like a humbucker. Thus, the "quack" sound of the second and fourth switch positions favored by many guitarists are virtually noise-free. [citation needed]
[edit] Alternative humbucker designs
[edit] Strat-sized humbuckers
Solid body guitars such as Fender Stratocasters usually feature cavities only for single-coil pickups. Installing full-sized humbuckers requires additional routing of the woodwork and the pickguard (if any). If the process is not carefully done, the instrument's body and pickguard may be damaged, sometimes even to the extent of affecting the tone produced by the body. This is unacceptable, especially for expensive vintage guitars where it is vital to preserve cosmetic appearance. As a result, many pickup manufacturers now produce humbucking pickups compacted into the size of a single coil. Although the Fender Stratocaster-style single coil is by far the most frequently found pickup in a single coil size, humbuckers are available for most single-coil guitars. Fender produces several variations in their Telecaster, Jaguar, Jazzmaster, and Mustang guitars.
[edit] Mini-Humbuckers
Mini-humbuckers were originally featured on Epiphone electric guitars (manufactured by Gibson) and several of Gibson's archtop jazz guitars. Mini-humbuckers were also used on Gibson Firebird guitars, thus giving them a very distinctive tone. By the 1970s, mini-humbuckers had replaced Gibson's original P-90 single-coil pickups on several of Gibson's budget guitar models, such as the Les Paul Deluxe. Only select reissue Gibson models are still made with Mini-Humbuckers, as they aren't the most popular with players. The Firebird, for example, produces clearer, brighter tones that are quite unlike typical Gibson sounds, and fit well between single coils and full-sized humbuckers in the tonal spectrum.
[edit] Fender Precision Bass
The most significant modification made to the Fender Precision Bass in its long production life has been the introduction in 1957 of a split pickup, wired in humbucking fashion, with one coil serving the E and A strings, the other the D and G strings. This unusual arrangement combines a clean single-coil sound with the noise reduction of a humbucker.
[edit] Coil splits
Some guitars which have humbucker pickups feature coil splits, which allow the humbucker pickups to act as "pseudo-single" coils. The electrical circuit of the pickup is reduced to that of a true single coil while the magnetic circuit retains its original closed loop configuration. Usually, this feature is activated using a switch on the tone potentiometer. Coil split turns on when potentiometer is pulled out and reverts back off when it is pushed in. The resultant single coil sound is not the same as a Fender single coil sound because the poles of the coil are made of steel and not of Alnico, and the coil turns are significantly less than a Fender pickup (5,000 as distinct to 8,000).
- Note: this is often wrongly referred to as "coil taps". Coil taps are more commonly found on single coil pickups, and involve an extra hook-up wire being included during the manufacture of the pickup so the guitarist can choose to have all the windings of the pickup included in the circuit, for a fatter, higher output sound; or some of the windings in use and some "tapped off" for a brighter, lower output, cleaner sound.
[edit] See also
[edit] References
- US2896491 (1959-07-28) Seth Lover Magnetic pickup for stringed musical instrument
