Photo by Greg Marra

Who Uses What?
The rule used to be “use 250k potentiometers with single-coils and 500k pots with humbuckers.” But let’s play with that notion a bit.

Old Gibsons had 250k pots, but their humbuckers were relatively low output, with low DC resistance compared to modern rock and metal humbuckers. Let’s look at a higher-output humbucker: the iconic Seymour Duncan JB, which has a very aggressive high-midrange peak. With 500k pots it yields a screaming overdrive tone. But when Seymour himself uses one, it’s often with 250k pots, playing with his bare fingers. Wired and played this way, the pickup produces a thicker, stronger, warmer tone.

Vintage Stratocasters use 250k pots, but the vintage wiring scheme leaves the bridge pickup without a tone control. Other things being equal, the bridge-position pickup is even peakier than the neck and middle pickups. Many modern players wire a tone control to the bridge pickup, but this mellows the bridge pickup simply by being in the circuit—even if the tone control is all the way up! If your single-coil pickups seem dull and lackluster, try stepping up to 500k pots. (Or try “no load” pots, available from Fender and other manufacturers. When these pot are turned all the way up, the pot is effectively removed from the circuit. You hear your pickups as if they were wired directly to the guitar’s output jack.)

With Telecasters, things get interesting. Most Teles use 250k pots, though some are as high as 1 Meg. Capacitor values (and circuitry) vary wildly depending on the guitar’s date, and whether Fender used the so-called “dark” Tele circuit. If you aim to use your tone control to replicate some of the dark-circuit tones, you’ll have to match those capacitor values, one of which was a hefty .1 µF! Sometimes these caps were hard-wired into specific positions on the 3-way switch.

A bit of experimentation just may transform your guitars in ways that better suit your style and tastes.

Instead of getting into the relative virtues of various vintage-correct wiring schemes, however, we’ll limit ourselves to sound clips of various cap values wired to a tone control in the usual way.

And how about stacked single-coils? There are many such designs, but in passive models the bottom coil always adds to the resistive load of the top coil. That’s why I usually like to use pots with values of 500k or more here. Stacked designs have already forfeited the sharp peak inherent in a true single-coil, and higher-value pots let the maximum peak get through.

About the Sound Clips
For all clips, I connected a short cable to a buffer (a Wampler dB+) and ran from there into a 1968 Fender Showman and a Naylor 12" speaker. For the dirty clips, I added two Wampler pedals, a Plexi-Drive and a Plextortion. (This may not be your favorite tone, but it highlights the differences well.) I used the buffer to best isolate the pots and caps. Depending on the first thing in your signal path—be it a germanium fuzz, various tube amps, or even a tuner pedal—you might find that certain pots and caps change the behavior of these devices as well. Since I can’t predict all of those variables, the buffer lets us focus on what’s actually coming out of the guitar, unaffected by downstream components. There’s a semi-clean, edge-of-breakup clip followed by a dirty clip, so you can hear how the peak (or lack thereof) influences the overdriven tone.

I’ve isolated the clips that demonstrate varying pot values from those showcasing different cap values. First comes the pot-value clip (the capacitor, a .022µf, is constant throughout, with the tone control always on 10). We start with no load, then 1 Meg, 500k, and 250k pots, always with the pots on 10. All the pots are ceramic Bourns 15-percent audio-taper models. The humbucker clips feature a Les Paul-style guitar with a Duncan Antiquity JB in the bridge and a Duncan Seth Lover at the neck. The Tele-style clips employ an ash/maple Tele with a stock Fralin Tele set (with a hybrid pole stagger).


Photo by Greg Marra

Comparing capacitor values in tone circuits (sweeping the tone control)

For the capacitor comparison, I’ve stuck with 500k pots so you can hear how various cap values affect the sound. The values are .047 µF, .022 µF, and .015 µF (plus a bonus .0015 µF on the Telecasters, upon Lindy's recommendation).

Comparing capacitor values in tone circuits (sweeping the tone control)

Frank, What Do You Like Best?
I’m flattered you’d ask! I’m a huge pickup fan. I have about 50 guitars, and almost none have duplicate pickups. I like to hear the differences—the character of each pickup. Even with weak single-coils I often use 500k pots. But if you’re not totally in love with the sound of your pickup(s), a 250k pot might deemphasize the characteristics you dislike, freeing you up to make different EQ choices on your amp and pedals.

What About Combining Values?
Pot resistance stacks up. When you have a 500k volume pot and a 500k tone pot, the pickup sees the equivalent of one 250k pot. Some players deliberately choose a 250k for volume and a no-load for tone. That way, the pickup only sees a 250k load, but the player still gets their desired taper. You could choose a 500k volume and 250k tone (or vice versa) in order to get the sound between those two values when both knobs are all the way up. You can also mix values in a Les Paul-type guitar. For example, you might mellow the bridge with 250k and sharpen the neck with 500k.

I hope these sound clips help you recognize how pot and cap values affect your pickups’ sound so you can make smart decisions about the best parts needed for your perfect tone.