A P.A.F., or simply PAF ("Patent Applied For"), is an early model of the humbucker guitar pickup invented by Seth Lover in 1955, so named for the "Patent Applied For" decal placed on the baseplate of each pickup. Gibson used the PAF on guitars from late 1956 until late 1962, long after the patent was granted. They were replaced by the Patent Number (Pat No) pickup, essentially a refined version of the PAF. These were in turn replaced by "T-Top" humbuckers in 1967, and production ended in 1975. Though it was not the first humbucking pickup ever, it was the first to gain widespread use, as the PAF's hum-free signal, tonal clarity, and touch sensitivity when paired with higher-gain amplifiers made the pickups popular with rock and blues guitarists. The PAF is an essential tonal characteristic of the now-famous 1957–1960 Gibson Les Paul Standard guitars, and pickups of this type have gained a large following.
History
Development
In the mid-1950s Gibson looked to create a new guitar pickup different from existing popular single coil designs. Gibson had already developed the Charlie Christian pickup and P-90 in the 1930s and 40s; however, these designs—like competitor Fender's single-coil pickups—were fraught with inherent 60-cycle hum sound interference.
Engineer and Gibson employee Seth Lover had developed a hum-canceling circuit for amplifier power supplies and suspected the same concept could be applied to guitar pickups. Ted McCarty authorized the project and Lover spent much of 1954 working on this noise-cancelling or "hum-bucking" pickup design. By early 1955, the design was completed. Rather than routing two single coil pickups in parallel, Lover had "routed two coils with opposite wind and polarity together in series, which caused each coil to cancel out the other’s hum." The design was given the part code P-490 and in June 1955, Lover and Gibson filed a joint patent. The original design called explicitly for Alnico 5 magnets, but early examples can be Alnico 2, Alnico 3, or Alnico 5.
Early use
Gibson began switching from P-90s to PAFs first on the company's lap steel guitars in 1956, and then on electric guitars debuted at the NAMM Show in 1957. Les Paul Goldtops and Customs were the first solid-body electric guitars to receive PAF humbuckers, and Gibson's ES Series were the first hollow/semi-hollow designs to receive them.
The Les Pauls of 1957 featured a black sticker with gold lettering applied to each pickup's underside, reading "PATENT APPLIED FOR." Over time the Patent Applied For sticker present on these pickups has evolved into the acronym P.A.F. as a way to identify pickups with this sticker. The patent for Gibson's design () was eventually issued on July 28, 1959. The acronym P.A.F. is also sometimes written as PAF leaving the periods out. However, in 1978 the word "PAF" was registered as a trademark by DiMarzio. (This registered trademark should not be confused with original P.A.F. acronym used to describe the original vintage pickups made by Gibson and the subject of this article.)
In 1958 the Goldtop model was dropped from production, and the sunburst Standard took its place. These guitars were all fitted with PAF humbuckers, which contributed greatly to the instruments' sound.
1961–1966
Early 1961 PAFs are almost exactly identical to the original 1957–1960 PAFs. In July 1961 Gibson standardized the PAF construction process with the introduction of the SG model. With this, smaller Alnico 5 magnets became standard. Transition to a new start lead location and a more formal number of wire winds was also introduced, leading to pickup DC resistance to center around 7.5kΩ. In addition, around 1963 these pickups were given a new sticker that had a patent number written on it. However, the stickers were, and continued to be, labelled with "", which is the number issued to the 1952 Les Paul trapeze tailpiece design and not the humbucking pickups. Between 1965 and 1966, Gibson switched to polyurethane-coated wire from enamel-coated to cut costs and streamline pigtail lead soldering time, changing the wire color from purple to red.