|Period||1946–1957, reissues since 1968|
|Magnet type||Alnico 3 (early), Alnico 5 (later)|
|Voltage (RMS), V||241.1 mV at 6.405 kHz resonant frequency|
|Voltage (peak), V|
|Impedance, kΩ||747 kΩ at 6.405 kHz resonant frequency|
||This article needs additional citations for verification. (June 2010)|
P-90 pickups were introduced in 1946, when Gibson resumed guitar production after World War II. They were initially used to replace Gibson's original "bar" or "blade" pickup (also known by many as the "Charlie Christian pickup") on models such as the ES-150, and by the end of the 1940s it was the standard pickup on all models.
The P-90's reign as the Gibson standard pickup was short-lived, however, as a new design of pickup, the humbucker, was introduced in 1957. Equipped with double coils, the new pickup boasted greater output and less hum. This new pickup, occasionally named PAF, very quickly took over as the preferred choice for all Gibson models, relegating the P-90 to budget models such as the ES-330, the Les Paul Junior and Special, and the SG Junior and Special, such as those used by Pete Townshend and Carlos Santana. This trend continued throughout the 1960s and particularly in the early 1970s, where the pickup all but disappeared from the entire Gibson range. By the 1970s, smaller single-coil pickups, mini-humbucking pickups, and uncovered humbucking pickups began replacing the P-90 pickups on Gibson's budget and lower-end models.
In 1968, however, Gibson re-issued the original, single-cutaway Les Paul - one version of which was a Goldtop with P-90 pickups. In 1972, they produced Limited Edition reissues - the "58 Reissue" - actually based on the '54 Goldtop Les Paul, with a stopbar tailpiece; and the '54 Custom, the Black Beauty, equipped with a P-90 in the bridge and an Alnico 5 pickup at the neck - the total production of these guitars was quite small. In 1974, Gibson put the P-90 pickup in their Les Paul '55, a reissue of the Les Paul Special from that era. It was followed in 1976 by the Les Paul Special Double-cutaway model and in 1978 by the Les Paul Pro (which had an Ebony fingerboard with trapezoid inlays). Since the 1970s the P-90 pickup has seen some success in various models in the Gibson line, mostly through reissues and custom versions of existing models. Currently it is featured most prominently on the Les Paul Faded Doublecut, and certain models in the "Historic" range.
In the early 1970s, Punk rock guitarists such as Johnny Thunders of The New York Dolls began using Les Paul Juniors and Les Paul Specials equipped with P-90's because of the cutting overdriven sound and the inexpensive nature of the guitars. In both The Dolls and The Heartbreakers, Thunders had a big influence on younger punk rock guitarists who adopted his look and choice of guitar. Mick Jones of The Clash and Steve Jones of The Sex Pistols both owned Les Paul Juniors, and the double cutaway Junior became the first choice for punk rock guitarists.
The P-90 was also marketed by Gibson in the 1970s as the "Laid Back" pickup, as part of a line of "named" pickups.
There are three major varieties of P-90 casing:
- Soap bar casing has true rectangular shape and the mounting screws are contained within the coil perimeter, positioned between the pole pieces, between the second and third strings and between the fourth and fifth strings, thus creating an irregular and somewhat unusual pattern. Occasionally they are mistaken for pole pieces, thus sometimes the P-90 is erroneously said to have eight pole pieces. The "soap bar" nickname most probably comes from its predominantly rectangular shape and proportions, and the fact, that the first P-90s on the original Gibson Les Paul Model of 1952 were white. A variant of the Soap-Bar P-90 is one, which uses the "dog ear" mounting plate, or frame, but the "soap bar" cover. The reason for the variation was to mount the pickup from a flat overlaying pickguard, such as is found on the Gibson SG Special (and other SG guitars using P-90's). The "dog ear" mounting plate is fitted with screws and springs, that attach it to the flat pickguard and allow the pickup to hang within the body rout. The soap bar cover is used, and the soap bar mounting screws are used to affix the cover to the dog ear plate.
- Dog ear is a casing type with extensions at both sides of pickup, that somewhat resemble dog's ears. These are extensions of the predominantly rectangular cover, that encompass the outlying mounting screws. Dog-ear P-90 pickups were commonly mounted on Gibson's hollow body guitars like the ES-330 and occasionally on solid body models like the Les Paul Junior. The same pickups were also available on Epiphone models (since Gibson was building Epiphone guitars in the 1950s) and the design is best remembered for its appearance on the hollow body Epiphone Casino of the mid to late 1960s. All three Beatles guitarists bought one, and recently[when?], Paul McCartney said, "If I had to choose one electric guitar, it would be this one."
- Humbucker Casing The Gibson designed P-90s come in a unique shape, wider than a Fender-style single coil but narrower than a humbucker, and longer than both. If one wanted to install a P-90 in a guitar routed for humbucker pickups (a Les Paul Standard for example), the existing rout in the body would have to be modified. This may result in aesthetic issues, due to gaps between the body and hardware, or even structural problems, as is the case, when re-routing the neck humbucker opening on a Gibson SG guitar. Because of this, "pseudo" P-90s in a humbucker-sized casing are common (see below).
Being a single-coil design, the tone of a P-90 is somewhat brighter and more transparent than a humbucker, though not quite as crisp and snappy as Fender's single-coil pickups. The tone therefore shares some of the single coil twang, but having large amounts of midrange and often described as brisk. Popular guitars, that use/have the option of using P-90s are the Gibson SG, Gibson Les Paul, Ernie Ball Axis series and the Epiphone Casino. Fender Jazzmaster pickups are often confused with the P-90, however, their only similarity is cosmetic, since there are many significant visual, dimensional and electrical differences.
All Gibson P-90 pickups (vintage and otherwise) were machine wound on Lesona coil winding machines, although their electrical specifications may vary slightly due to operator error. In common with many other modern pickup types, there are two versions of modern P-90: neck and bridge version. Their DC resistance tends to be around 7-8 kΩ for neck pickups and 8-9 kΩ for bridge pickups. Early P-90 pickups made before approx. 1974 were manufactured with no difference in the bridge and neck position and were interchangeable. After winding, pickups were hung on a rack holding 20 pickups and assembled according to the model of guitar they were to be used on (Soap-Bar or Dog Ear). Earlier pickups (around 1952) had Alnico 3 magnets, but in 1957 Gibson switched to Alnico 5.
Hum-canceling and humbucker-shaped versions 
One drawback of the P-90 pickup is its susceptibility to 50 Hz / 60 Hz mains hum induced in its coil by external electro-magnetic fields originating in mains powered electrical appliances, motors, lighting ballasts and transformers, etc. This susceptibility is common to all single-coil pickup designs, but the P-90, having around 2,000 more turns of wire in its coil than Fender pickups, produces a relatively large amount. Several manufacturers now make hum-canceling pickups that resemble the P-90 and are claimed to have a similar sound.
There are two types of noise canceling P-90: stacked coils and side-by-side coils. In the first case, a second coil is placed below the main one; due to its position, the amount of sound picked up from the strings' vibration is almost negligible but, due to its close proximity to the main coil, the amount of hum it picks up is very similar and it is effectively canceled by connecting both coils out of phase. This design has acquired a bad reputation among musicians, unlike that side-by-side configuration. In that configuration the operation is the same as in a typical humbucker: both coils sense the strings' vibration and, being connected out of phase but with the position of the magnet giving them opposite magnetic polarities, the signal from both coils is added, while the hum (which is not affected by the magnetic polarity of each coil) is effectively canceled. Consequently these types of pickups sound more like a humbucker than a P-90, since they are in effect the same as Gibson's mini-humbucker.
Around 1970 Gibson replaced the P-90 on several models with a mini side-by-side humbucker. This pickup was originally used on Epiphone models such as the Sheraton and was interchangeable with the P-90. In response to a resurgence of popularity of the P-90 Gibson issued the P-100, a stacked version (see above) of the P-90. Gibson also makes a new P-90 version called the H-90, which is found in Billie Joe Armstrong Signature Guitar (Les Paul Junior). The H-90 has two stacked coils, but Gibson claims that it does not lose the characteristics of a P-90. It also has a higher output.