What are “asymmetrical” or “offset” coils? And how do they influence the tone of a humbucker.
Both terms mean that one of the humbucker coils is wound hotter than the other. There are a few reasons this is done. It makes the pickup brighter. I can tune the frequency of a pickup with this technique (among others). There’s a lot of rumor and speculation about whether or not vintage P.A.F.’s intentionally had offset coils. They did not. When they were produced with offsets it was accidental. There’s many things about old pickups that was accidental or unintentional and it’s why so many vintage pickups, be they single coils or humbuckers, are either really good or really bad.
Another reason to offset coils is to make a pickup more dynamic. What I mean by dynamic is a more open and complex frequency expression. Think about compression and how it squeezes the peaks and the valleys and the highs and the lows. Dynamic is the opposite of that.
There is a tremendous amount of minutia involved in this technique. Like the winding of any pickup and the mastery of winding pickups it takes a lot of experience. The only thing that can be done is to wind a humbucker over and over again trying different turns per layer, different tensions, different speeds, different offsets, and different alloys.