A single coil pickup is a type of magnetic transducer for the electric guitar and the electric bass. It electromagnetically converts the vibration of the strings to an electric signal. This article focuses on single coil only pickup designs, for more information about pickups in general, see pickup article.
In the mid 1920s George Beauchamp, a Los Angeles, California guitarist, began experimentation with electric amplification of the guitar. Originally using a phonograph pickup assembly, Beauchamp began testing many different combinations of coils and magnets hoping to create the first electromagnetic guitar pickup. He wound his earliest coils using a motor out of a washing machine, later on switching to a sewing machine motor, and eventually using single coiled magnets.
Beauchamp was backed in his efforts by Adolph Rickenbacker, an engineer and wealthy owner of a successful tool and die business. Beauchamp eventually produced the first successful single coil pickup. The pickup consisted of two massive "U" shaped magnets and one coil and was known as the "horseshoe pickup". The two horseshoe-shaped magnets surrounded the strings that passed over a single core plate (or blade) in the center of the coil.
Beauchamp outfitted the pickup in a custom built lap slide guitar. The production model based on this prototype became the Hawaiian Electro lap steel guitar, nicknamed the "Frying Pan" for its round, flat body.
In 1931 Beauchamp founded the Ro-Pat-In Company with Rickenbacker and his associates. Ro-Pat-In eventually became The Electro String Instrument Corporation and subsequently the Rickenbacker International Corporation. The company introduced its first "Electro-String Instruments" to the public in 1932.
In 1936 Gibson introduced the ES-150, its first electric Spanish styled guitar. The ES-150 was outfitted with the bar pickup. Jazz guitar innovator, Charlie Christian, began playing an ES-150 in the late 1930s with the Benny Goodman Orchestra. This caused the popularity of the electrified guitar to soar. Due to Christian’s close association with the ES-150 it began being referred to as the “Charlie Christian Model” and Gibson’s now famous bar pickup as the “Charlie Christian pickup” or “CC unit”.
The P-90 is a single coil pickup designed by the Gibson Guitar Corporation. These pickups have a large flat coil with adjustable steel screws as pole pieces, and a pair of flat alnico bar magnets lying under the coil bobbin. The adjustable pole pieces pick up the magnetism from the magnets. Moving the screw closer or further away from the magnet affects signal strength, thus tone as well. There are 2 major varieties of P-90 pickup that differ mainly by mounting options:
The sound of P-90 is somewhat brighter and more transparent than a later Gibson pickup, a humbucker, though not quite as crisp and snappy as Fender's single coil pickups.
The Fender Telecaster features two single-coils. The neck pickup produces a mellower sound, while the bridge pickup produces an extremely twangy, sharp tone with exaggerated treble response, because the bridge pickup is mounted on a steel plate. These design elements allow musicians to emulate steel guitar sounds, making it particularly appropriate for country music.
Pickups are selected with a 3-position switch, and two wiring schemes exist:
The Fender Esquire has a variation to the Vintage wiring scheme by using the scheme on a single pickup. This gives a treble cutoff in the neck position, normal in the middle position, and a tone control cutoff in the bridge position.
The traditional Stratocaster design guitar features three single-coils. The guitarist can control what pickup or pickup combination to activate with a lever switch. They are usually referred to as the bridge, middle and neck pickups based on their proximity to those parts of the instrument.
Pickup position, number of coil winds, wire types, magnets and other factors shape the tone. Pickups in the neck position usually give louder, mellower and warmer sound, while bridge pickups have lower output and produce a brighter, sharper and more harmonic-rich tone. The reason the neck pickup has the most output is that the string's vibration has a higher amplitude at the neck position. Some manufacturers overwind the bridge pickup for more output to compensate for this difference.
The poles have different heights. This staggering is done to compensate for the output of each string for two reasons. The first reason is because the fretboard has a radius (also called camber) of between 7 and 12 inches. Naturally the strings will follow the radius of the fretboard and so must the magnets, generally speaking. The second reason is that some strings have naturally higher output, the plain or unwound G string being the most significant and this calls for these magnets to be further compensated, resulting in an apparent odd looking stagger. Fender Strat pickups generally follow the traditional design and have the G string's magnet as high as the D string's, but this causes the G string to overly dominate all the other strings due to its higher output. Traditionally in the 1950s and 1960s, string sets came with a wound G string, but it was difficult to bend across the fretboard in modern rock and blues styles of music. In the 1970s, string manufacturers introduced the non-wound G string, which was easier to bend, but had a much higher output. In order for the G string to have the same output the G pole should have the greatest gap between the string.
The pickup selection switch has 5 positions. Positions 1, 3 and 5 activate only one pickup (bridge, middle or neck respectively), while positions 2 and 4 activate a combination of two pickups (bridge and middle, or middle and neck, respectively). Some pickup sets have a reverse wound and reverse polarity middle pickup that when in combination with the normal bridge or neck pickups will cancel electromagnetic interference (noise/hum). The sonic effect of positions 2 and 4 is sometimes referred to as a "quack", and some guitar notation includes directions to use these pickup combinations. One example is "Sultans of Swing" by Dire Straits which is played in position 2 (bridge and middle). Early Stratocasters had only a three-way selector, but innovative guitarists found they could get an interesting tone by carefully balancing the selector switch lever between positions. Later on, Fender introduced the now standard 5 way selector switch.
There are several well-known single-coil pickups that have a distinctive sound: