Pickup Resistance

This PAF is fuller on one side than it is on the other. Sometimes it fuller in the middle. Sometimes on both edges. Thanks to the Throbak site for the photo.

When I see a double white PAF for sale, it’s hard for me to keep my trigger finger off of the “Buy it Now”. I just can’t resist. “What?” “Not that kind of pickup resistance?” Oh, you mean the electrical kind with ohms and stuff. Ok, we can do that. Joking aside, there is an awful lot that has been written about “hot” pickups and resistance. I’m going to defer a bit to Seymour Duncan for the technical stuff and then I’ll chime in with my opinion based on practical experience. Seymour tells us: Resistance to the flow of alternating current is called impedance and it changes with frequency. The frequency where a pickup’s impedance reaches its highest level is called the resonant peak. Generally speaking, the higher in frequency the resonant peak, the clearer and brighter the pickup’s tone. The higher the DC resistance-the ohm number you see that is usually between 7K and 9K on vintage pickups, the lower the resonant peak. So, a high DC resistance-lower resonant peak equals less brightness.

Here’s a PAF-thanks to the Throbak site-that is wound fairly evenly. The configuration of the windings can have a big effect on the tone of a pickup.

Surprised? I was because most people put the higher resistance pickup in the bridge position where you want bright. However, a high ohm number doesn’t mean a dark pickup and that’s where the idea of “hotter” pickups comes in. According to Seymour, who should know, The higher the ohms number, the higher the output and the “fatter” the tone. Too high and it does the opposite. Too low and its thin and weak. So, to me, my original instinct that a high ohm number in the bridge position still makes sense given this information. But, be aware that higher resistance comes at the expense of dynamics and high end. The thing is, though, that there is so much more to pickup character, that using only the DC resistance is kind of missing the point. The type of magnet-Alnico 5 or Alnico 2 makes a discernable difference and the way the pickup is wound makes a difference as well. Is it evenly spaced on the bobbin? Is it piled up in the middle? the edge? both edges but not the middle? That’s another reason why PAFs are so different from each other. PAFs were wound by machine-The Leesona 102 was one of them- the number of windings and the pattern were supposedly controlled by the machine. But, apparently, in practice, they weren’t or at least not completely. As I understand it, they had to be calibrated for different types of pickups and the setup was often done quickly or carelessly or not at all.  I read that the timers/automatic shutoffs didn’t work and so somebody had to stop the winding.  PAFs had all kinds of windings and all kinds of DC resistance since they wound them “until the bobbin was full” in other words, by eye. Here’s my theory on why double whites tend to be higher resistance: When you’re winding dark copper wire on a black bobbin, its hard to see if you’re getting to the end of the capacity. With a white bobbin, its easier to see that there is more room to wind more wire, so you continue on a little longer. Thus, a “hotter” pickup. Just my theory based on the fact that most of the DW PAFs I’ve had are 8K and above. The highest I’ve found was around 9.2K in a neck pickup on a 59 ES 345. Once they got to using a fully automatic winder, the variations became much less and some of the “magic” went away. But consistency replaced it and where early PAFs can be a crapshoot, the later PAFs and early Patent Number pickups are more consistently excellent, IMO. Many of the best pickups I ever owned were in the 7.7-7.9K range. To me, that seems to be a sweet spot-at least as far as the DC resistance goes. I’ll talk about Alnico 5 vs Alnico 2 in the next post.

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