The Legendary ‘PAF’: 60 Years Since the Hallowed Humbucker Met the Gibson Guitar
The term “PAF” has become almost generic for any vintage-style humbucker, but accurately speaking, it is tied to a very specific make of pickup that was first used on a Gibson electric guitar 60 years ago this year, and one that has since become the most revered and most valuable guitar pickup ever created.
Gibson president Ted McCarty tasked engineers Seth Lover and Walter Fuller with developing a hum-cancelling pickup in 1955, and Lover’s patent application actually stems from June 22 of that year. Although a few early renditions were used on Gibson lap-steel guitars in 1956, they weren’t seen on any standard electric guitars (aka “Spanish-electric”) until 1957, when they appeared most notably on Gibson’s Les Paul “Goldtop” and Les Paul Custom models. At that time, the bottom plate of these humbuckers carried a decal reading “Patent Applied For” (soon shortened by guitarists to “PAF”), presumably in an attempt to ward off imitators. Even after the patent was awarded on July 28, 1959, Gibson continued using the “Patent Applied For” stickers, until a new “Patent No 2,737,842” sticker came into use in late ’61 or early ’62 (rather obtusely, the number used on this new sticker was in fact that for the patent of a Gibson bridge design of the early ’50s, and not the actual number attached to the humbucking pickup patent granted in ’59).
What matters most about these early humbuckers, however, is not the sticker so much as what’s going on underneath it. Let’s take a little look at some of the ingredients that make the legendary PAF such a desirable pickup, and what Gibson has done in recent years to re-captured that sought-after vintage tone and playing feel.
First off, though, it’s worth noting that Lover was said to have liked the sound of the single-coil Gibson P-90 pickup that preceded the humbucker (and which remained in use on several models), and the components used in the new hum-cancelling design are really very much the same parts. These include approximately 10,000 turns of 42 AWG wire and Alnico bar magnets (two in the P-90, one in the humbucker), reconfigured into a two-coil design rather than a single coil. As such, a good PAF has a lot in common, sonically, with a good P-90 from the same era, even though this “reconfiguration” of the ingredients both reduces the hum in the signal, and introduces some new elements into the overall tone, too.
Lover and Fuller’s new design used two coils wound in the reverse of each other and charged with opposite magnetic polarity, positioned side by side and connected in series. The configuration rejected much of the hum induced in single-coil pickups when in proximity of many electrical appliances, while also presenting a broader magnetic window that enhanced a warm, full sound. In its original form, the Gibson humbucker is also notable for its impressive clarity, as well as an appealing “bite” or “edge” to the attack, all couched within abundant harmonic overtones that lend a lot of texture to the guitar’s sound, and an appealingly playable compression that doesn’t impede note definition. Several elements of the way these pickups were manufactured are thought to have attributed to these characteristics:
Unevenly wound coils: the winding machines that Gibson used in Kalamazoo in the late ’50s and early ’60s were not perfect creations, and they wound the pickups’ coils in a somewhat uneven manner (a practice that is sometimes today called “scatter wound”) that contributed to a certain added harmonic texture and liveliness and some extra “bite” in the pickup’s response.
Unevenly matched coils: in addition to the above, each coil was wound a little differently, both as regards winding pattern and the overall amount of wire loaded onto it. Putting two slightly mismatched coils side is believed to add further harmonic complexity, as well as some “edge” and clarity that help define the PAF sound.
No wax potting: the PAF pickups’ coils were left unpotted (the process off dipping a pickup in hot wax or paraffin to seal its coil windings and reduce unwanted microphony), and the slight microphonic ring that can be induced in these coils as a result can further contribute to the PAF’s sense of “liveliness” and harmonic texture.
Add it all up—along with the early un-polished long 2 ½” Alnico magnets and the precise makeup of other metal components—and these ingredients resulted in what is commonly considered to be the most expressive pickup ever designed. The manufacturing processes for these humbuckers were far from set it stone, though, and sampling a selection of original PAFs side by side usually results in some noticeably different results.
The irregular winding patterns, as described above, clearly contribute to this variance between units, as did the somewhat random use of Alnico II, III and V. Greatly varying amounts of coil wire were also used, meaning that DC resistance readings for vintage PAFs can range from anywhere in the upper 6k and lower 7k range (all in Ohms) to the mid and even upper 8k range. The results tend to be heard as bright, clear, articulate pickups at the lower end of that spectrum, and fat, thick, hot pickups in the upper end, although it’s worth noting that far more is at play in determining any PAF’s sound and supposed output than these DC resistance readings alone.
In 1961 Gibson started using slightly shorter (2 3/8”) polished Alnico magnets, while also purportedly becoming more consistent in both the use of Alnico V (a detail that I’m unable to entirely verify), and of the amount of wire used in total, aiming for an approximate DC resistance of 7.5k ohms. Variables remained, and these later PAFs—as well as the “Patent No” pickups of 1962 which were identical in all but the sticker—will still usually sound different one from the other, although they do tend to be somewhat more consistent than earlier PAFs, as a group. After 1963, Gibson changed its wire type again, and other factors in the humbuckers’ makeup also began to vary, all of which really marked the end of the PAF era.
Given that original PAFs carry such a high value, both in utilitarian and monetary terms (you want an authentic pair in good condition? Head to bank… withdraw a minimum of $5,000… and start looking), it’s no surprise that pickup makers have struggled to reproduce the formula for many years now.
Gibson has recently been at the forefront of the effort, returning to original specs, materials, and manufacturing processes as much as is humanly possible in the creation of its two leading “PAF repro” designs in use today. Both the Customer Buckers from Gibson Custom and the Memphis Historic Spec (MHS) humbuckers from Gibson Memphis use the essential techniques outlined above—unevenly wound and mismatched coils, with no wax potting—to get as close to PAF-like tone as is possible today. Other pickups like Gibson’s Burst Bucker and Burst Bucker Pro designs and the popular Classic 57 take advantage of several tricks learned from genuine PAF construction to marry vintage-certified tone with modern performance factors suitable to today’s player.
Photos: Dave Hunter