The Evolution of Gibson's Early Pickup Designs

 

In the mid-'30s, Gibson set out to create a pickup that would allow the electric guitar to be heard more clearly and effectively in larger ensembles. The Charlie Christian pickup, introduced with the ES-150 in 1936, was a large, single-coil design that significantly increased the electric guitar’s volume and presence, allowing it to compete with louder instruments in big bands. At the time, electric guitar technology was still in its infancy, and pickup design was an emerging and experimental field.

Gibson’s engineers, led by Walt Fuller, introduced cobalt-based magnets in this pickup, marking one of the earliest uses of this material in electric guitar pickups. This was a key distinction from the later adoption of Alnico magnets, which would become more common in subsequent models. The Charlie Christian pickup used 38 AWG wire, and was notably large, weighing approximately 1.5 pounds. Its two large cobalt magnets were hidden inside the guitar, making it both an impressive technological advancement and a physical innovation in the design of pickups. While this pickup represented a significant leap in electric guitar technology, it also marked the beginning of a long process of refinement and experimentation that ultimately led to the creation of the P-90, which would become a hallmark of Gibson’s pickup designs.

As Gibson’s pickup designs continued to evolve in the early '40s, they introduced a distinctive diagonally mounted pickup in 1940, which spanned from the neck to the bridge of the guitar. This was an innovative design that provided a unique tonal response. In 1941, this pickup was refined and shortened, with the new version often referred to as the "Short Slant" pickup. This model featured two Alnico bar magnets, a steel keeper bar for magnetic stability, adjustable pole screws for tonal customization, and a rounded plastic cover that contributed to both its aesthetic and practical design. These improvements greatly enhanced the tonal quality and versatility of the pickup, allowing for a more dynamic range of sounds suited to the evolving needs of guitarists at the time.

In 1940, Walt Fuller also finalized the development of the P-13 pickup, a more compact design that featured Alnico magnets. The P-13 was enclosed in a rectangular metal cover and included height-adjustment screws, except for the budget version, the P-13 MESG (Mastertone Electric Spanish Guitar), which lacked the adjustable pole screws found in the standard P-13. The P-13 was used on various Gibson models, including the ES-100, ES-125, ES-150, as well as lap steels. Known for its clear and balanced tonal quality, the P-13 was well-regarded by musicians and continued to be used by other manufacturers, such as Silvertone and Harmony, even after Gibson discontinued it in 1955.

Due to the constraints of wartime metal shortages and the factory’s shift to producing military supplies—such as airplane skids and submachine gun parts—Gibson’s electric pickup development stalled until the war ended in the mid-'40s. This period of interrupted production delayed the further advancement of electric guitar pickups, but it set the stage for the post-war era of increased innovation in guitar design.
 

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The P-90: A Revolutionary Pickup and Its Variants

1946 marked the culmination of earlier developments with the introduction of the P-90, a revolutionary pickup design that would become an industry benchmark. Walt Fuller synthesized elements from previous designs to create a pickup capable of delivering a dynamic, rich, and versatile tone.

The P-90 featured a machine-wound coil made of 42 AWG Plain Enamel wire, wound onto a black styrene plastic bobbin. Beneath the coil sat two 2 1/2 inch sandcast Alnico bar magnets, with their south poles facing inward. Adjustable polepieces passed through a steel keeper bar placed between the magnets, and all components were mounted on a zinc-plated brass baseplate. The pickup was concealed under a plastic (butyrate) cover.

The result was a pickup that offered a balanced tonal spectrum with a pronounced midrange growl that quickly became its defining characteristic. This distinctive sound proved ideal for genres like jazz, blues, and rock, where the P-90’s ability to articulate both high-end bite and low-end warmth made it a versatile choice for musicians seeking a unique voice. The P-90’s powerful, full-bodied tone and aggressive midrange set it apart from its predecessors, cementing its place as one of the most iconic and enduring designs in electric guitar history.

The use of Alnico magnets in the P-90 has been a subject of interest among vintage guitar enthusiasts. Early P-90s used Alnico 3 magnets ground flat only on the south side, leaving the other surfaces rough from sand casting. This worked since the north side didn't contact any part of the pickup. However, with the introduction of PAFs, the north side needed to make flush contact with the slugs in the second coil. Soon after, new magnet types with both faces ground flat were used in humbuckers, while P-90s continued using the original Alnico 3 magnets until the late '50s. Later models blended Alnico types, with Alnico 5 becoming widespread. Each magnet type influenced the tone: Alnico 2, for example, provided a smoother sound, while Alnico 5 delivered a stronger output and a brighter tone.

By the early '60s, Gibson standardized the use of Alnico 5 magnets, resulting in a tonal character emphasizing greater clarity and power. This shift helped the P-90 remain relevant even as the humbucker began to dominate the market. Since a P-90 uses two magnet bars, it generally has higher inductance compared to an humbucker, resulting in a lower resonant peak that contributes to its characteristic warmer, midrange-heavy tone.

As Gibson's lineup expanded, so did the variants of the P-90 pickup, each designed to accommodate various guitar configurations. The Dog-Ear, Soapbar, and Staple P-90s became the most recognizable versions, each offering its own distinctive mounting system and tonal characteristics.

The Dog-Ear P-90 was commonly found on hollow-body guitars like the ES-125 and ES-330, as well as on solid-body models like the Les Paul Junior. It featured an extended plastic cover and baseplate flanges with mounting screw holes on either end, allowing for secure attachment to the guitar body.

The Soapbar P-90, used on models like the Les Paul Goldtop, Custom, and Special, featured a unique mounting system. Instead of being mounted on a pickup ring, the P-90 was directly screwed into the guitar body, with screws positioned between the polepieces. The wire passed through a protective grommet, with the hookup lead connections and ground lug located on the underside of the baseplate. Height adjustment was achieved using either springs or shims, contributing to the pickup's more streamlined, traditional design.

The Staple P-90, used primarily in pre-1957 Les Paul Customs and jazz guitars, sought to emulate the tone of DeArmond's Dynasonic pickups. Created by Seth Lover, this version employed rectangular permanent magnets and individual polepiece height adjustment screws. Though less widely used than the Dog-Ear or Soapbar variants, the Staple P-90 holds an important place in the history of Gibson’s pickup evolution.

Like the PAF, the Soapbar P-90 saw changes from the early '60s onward. The magnets were shortened, and the magnet wire switched to poly-coated versions. By the mid-'60s, wooden shims were introduced under the magnets. Then, starting in 1969, the bobbins became transparent, a feature that remained until the '80s.

 

The Timeless Legacy of the P-90 Pickup

Since its introduction in 1946, the P-90 has become a signature of Gibson’s electric guitar lineup. Featured on models like the Les Paul Junior, its bold and articulate sound became synonymous with jazz, blues, and rock. The P-90’s ability to produce a broad tonal spectrum—from warm, rounded bass to sharp, cutting treble—made it an ideal choice for musicians seeking versatility and dynamic expression.

Though the introduction of the PAF humbucker in 1957 led to the P-90’s diminished prominence, it never disappeared entirely. It remained in production on various Gibson models and continued to be favored by musicians who appreciated its distinctive, raw sound. In recent years, the P-90 has experienced a resurgence in popularity, with players rediscovering its ability to deliver clarity, warmth, and aggression in equal measure. This versatility allows it to shine across various genres, from the smoothness of jazz solos to the gritty, punchy riffs of rock, and even the soulful expressions in blues.

Today, the P-90 is celebrated as a timeless pickup, embodying the innovative spirit that began in the late '30s. Its legacy is a testament to the vision of engineers like Walt Fuller, whose design continues to inspire guitarists worldwide, ensuring the P-90’s place in the pantheon of classic electric guitar pickups.

Written by Giuseppe Fumuso
 

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