In 1952, Gibson’s President Ted McCarty approached a 42-year-old naval radio engineer named Seth Lover to design a new kind of pickup.
Gibson and Gretsch had a problem with pickup hum. Both were competing with Fender’s brilliant marketing by producing big, powerful pickups, full of depth and character – put also prone to pick up electrical interference from the mains power supply: prone, that is, to ‘hum’.
The ’50s was a savage market. The guitar giants had to innovate constantly to defend their customer base. Solving pickup hum promised a clear market reward.
Seth Lover had been part of the Gibson team before the war, but had found better pay installing radars for the US Navy. Now Gibson was feeling more generous, and wanted Lover to get rid of the hum.
Lover’s solution was to take two pickups, connect them in series, but reverse them both electrically (by reversing the winding direction) and magnetically (by reversing the polarity of the magnet). The vibration of the strings produces current in the pickups in the same direction; but the ambient magnetic field produces current in opposite directions.
The result is that the current caused by the strings is increased due to constructive interference, but the hum currents – which are opposites – cancel each other out. The pickup is more powerful, but the hum is bucked.
The PAF is the same size as a P90. Under the cover there are two coils, sitting side-by-side. Only one of them has adjustable pole pieces – these are the ones which stick out through the cover. So whereas the P-90 has a row of pole pieces along its middle axis, the PAF’s are a quarter of the way from the long edge.
The PAF design evolved – and not, it seems, through deliberate redesign. It looks like Gibson let the specifications wander as they ran out of inventory and replaced coil wire, bobbins and magnets with whatever was available. Through the late 50s and early 60s, these subtle variations have all kinds of effects on the sound.
What all generations of PAFs have in common sonically is depth, weight, and definition. The constructive interference between the two coils gives the sound attack. When you strike the strings there’s an initial spike in the signal: not a ‘twang’, but more solid and articulate. With distortion, it’s a sharp crunch and a snarl; clean, the spike softens to a sound almost like droplets of water.
The sustained sound of a PAF is generally more mid-range than a single coil; richer, but usually less bright. Part of the reason for this is that the two coils of the humbucker are in slightly different positions under the strings. String overtones with nodes falling between the coils are cancelled out, and these tend to be the higher frequencies.
The combination of these is what creates the unique sound: a growl, human-voice-like singing. Distorted, the sound is rich and smooth. Clapton’s ‘woman tone’ is a PAF in the neck position with the tone control turned right down. With the trebles turned up the sound cuts through: it blazes.
That’s the basic PAF character. But around this there’s a lot of variation. The key is the number of winds on each bobbin. When the number of turns is exactly the same on both the pattern of constructive interference between them is very accurate, and the PAF has a creamy sound. But if there are slight differences, the twin coils accentuate different frequencies and the PAF takes on an individual character. Some people say that this difference in the number of coil windings is because the early coils were wound by hand, and that the people winding would lose track of how many they had put in. But Seth Lover himself denied that early PAFs were hand-wound; he says they had mechanical winders, but that they didn’t much care too much how many coil windings they put in – they just put on ‘Whatever would fill up the bobbin nicely’.
By the early ’70s, the PAF sound has changed. Better winding machines mean that the number of turns is precisely the same. Players called these pickups T-Tops because the bobbins had a letter T stamped on them (Lover said: to make ‘sure they keep the “T” on top when doing assembly’).
The T-tops, a.k.a. T-Buckers, are the sound of the 70s guitar: brighter and thinner than the PAFs. Still with that human voice-like quality; only now the voice is more constricted, and sometimes less expressive. The T-Tops give a tight, sizzling 70s glam sound; the sound still burns, but it’s held back, tighter.
Not many people prefer the T-Top to the PAFs; uniformity of production means reliability, but less accidental brilliance. Rather late in the day, the Gibson Corp. seems to have agreed. It now produces a range of pickups designed to the specification of the original PAFs, and these are supposed to be very good. But for the real thing, find yourself a vintage PAF – with all its variation, accident and technical genius.