It might not have been the first electric guitar pickup developed, but when Gibson’s Patent Applied For (PAF) humbucking pickup hit the scene it turned the industry’s thinking on its ear, and offered players unparalleled levels of sound and performance that set the standards for pickup design forever after. Check out the five-figure sums that collectors are willing to pay for an original pair of PAFs on the vintage market, or the way players flock in droves to accurate reproductions of these hallowed humbuckers, and you get an inkling of the impact they have had on the guitar world. Imagine how they must have appeared back in the mid 1950s when they appeared on their first Gibson guitars, in an era when your choice in pickups was single coil or… another single coil.

At the urging of company president Ted McCarty, Gibson technicians Seth Lover and Walt Fuller began working on the idea of a hum-rejecting guitar pickup in 1955. Lover, a radio and electronics expert, had worked for Gibson on and off in the 1940s, and after rejoining the company in 1952, he had developed the single-coil Alnico pickup, as used briefly in the neck position of the Les Paul Custom. Gibson’s main pickup of the day, the P-90, had a great full, fat, distinctive tone, but like all single-coil pickups was prone to picking up unwanted hum and noise from external electrical sources.

Being familiar with tube amplifiers, Lover was well aware of how a “choke” (a coil or small transformer) could help filter out hum induced by an amp’s power supply, and began working toward applying the same logic to guitar pickups. His solution took the form of a double-coil pickup, in which the two coils were placed side by side, wired together out of phase with each other, and given opposite magnetic polarities. As a result, this configuration rejected much of the hum that single-coil pickups reproduce—which is eliminated when two like but reverse-phase signals are summed together—but passed along all of the guitar tone. Lover also added a thin nickel cover to the pickups, to further reject electrostatic interference. In addition to the benefits regarding noise rejection, the double-coil pickup’s side-by-side coil alignment produced a warm, rich sound that came across as bigger and rounder than that of the average single-coil pickup.

Gibson dubbed Lover’s new creation the “humbucker” for its ability to “buck” electrical hum and, aware that it was a unique device in the fledgling industry, applied for a U.S. patent to protect the design. When double-coil humbuckers first appeared on Gibson’s Les Paul Goldtop and Les Paul Custom in 1957, they carried stickers that read “Patent Applied For” to warn off would-be copyists while the company awaited the patent. Pickups of the era, therefore, are given the nickname “PAF,” which applies to any pickup carrying the “Patent Applied For” sticker that all Gibson humbuckers wore between 1956 and late 1962. In fact, a U.S. patent was granted in July of 1959, but Gibson continued to apply these stickers for another two years. One theory is that the company still didn’t want potential copyists to have access to the design, as they could easily have done by searching for the patent number at the U.S. Patent Office (when the patent number stickers finally appeared on humbuckers late in 1962, the number was in fact for a bridge patent—perhaps a simple mistake, but also perhaps a further deterrent to the competition?). The second theory is that Gibson was just using up the many stickers it had already printed up, and perhaps had already applied to a stock of pickups.

The first “patent number pickups,” as the post-PAF humbuckers have come to be known, were almost identical to the final stocks of PAFs, which had become fairly consistent in their construction by 1962. But earlier examples of the late 1950s had varied quite widely and, as any collector knows, there are “great, greater, and greatest” versions out there (if you will). Gibson used a range of alnico magnet types in constructing these pickups, from alnico II through alnico V, largely determined by whatever stocks the company could lay its hands on in the day, and because coil winding was a hand-guided process, pickup coils were wound to differing numbers of turns, too, and therefore differing strengths. In addition to these constructional variables, another purely cosmetic variable has sent many collectors in search of the rare and ultra-rare examples: when Gibson ran short of black plastic coil formers, or “bobbins,” it bought in cream stock, so double-cream and black-and-cream PAFs—dubbed “zebra stripes”—can also be found beneath some pickups’ metal covers. 

PAFs are not really much hotter, in electrical terms, than the average P-90, and the two different pickup types from the same era generally show similar DC resistance readings in the 7.5k to 8.5k ohms range. But the humbucker’s broader sonic window sends a meatier spread of frequencies to the amp, which creates a fatter, warmer sound, and can also drive an amp more easily into distortion when desired. Nevertheless, a good PAF still yields a lot of sweetness, good treble response, and excellent definition, as exhibited by the best of Gibson’s current breed of PAF reproductions, the ’57 Classic and ’57 Classic Plus and the Burstbucker range. Winding a PAF-style humbucker a little hotter, however, creates a pickup that’s more suitable to some contemporary rock styles. The 490R, 490T, and 498T all give you crunch, drive, and sustain to spare, while retaining a core of sweetness and musicality. Pickups like the Screaming Ceramics  and Dirty Fingers up the ante even further by adding powerful ceramic magnets and extra windings, for the ultimate drive and heavy rock or nu-metal distortion tones. When it comes to ’buckers, it all starts with the hallowed PAF—and however hot you like your mustard, it all comes down to Gibson.