To Pot—Or Not?

Can you hear me now?

Most modern guitar pickups are potted. That means they’re dipped in wax to prevent their components from vibrating against each other in high-volume situations, which can produce unwanted feedback.

The process  also prevents pickups from becoming microphonic, amplifying sounds traveling through air along with the magnetic information generated by the pickups interacting with the strings. Some pickups are so microphonic, you can literally talk into the pickups and hear your voice through the amp.

Want to hear a pickup that sounds like a cheap megaphone?

Bath time! Potted pickups don't squeal.

Your wish is my command! I recently pickup up a cheapo semi-acoustic to use as a subject in fiendish pickup-transplant experiments in upcoming blog posts. The neck pickup on this bright red beauty is microphonic to the max:

Seriously Microphonic

So unpotted pickups are bad, right?

Not exactly. Many beloved vintage pickups aren’t potted. These often have a resonant midrange thrust, a quality some describe as a “honk.” Those protruding midrange frequencies can really help an guitar sound find its place in a mix, or cut through the bass and drums onstage.

Seymour Duncan is savvy to this fact, and some of the company’s coolest pickups are unpotted. Examples include the the Antiquity and Seth Lover humbuckers. I recently used the latter to transform a dull, uninspiring Les Paul in the life of the party. (You can read about the makeover here and here.) The new Zephyr series pickups are also not potted.

I love the slightly nasal resonance of the Seth Lovers, but wish there were prettier terms to describe the quality than “nasal” and “honk,” which don’t exactly sound like compliments.

I recently asked Seymour about this while hanging out in his office. I wondered why there are so few unpotted pickups nowadays, considering how many players are attracted to their character.

He talks about feedback problems unpotted pickups can cause in high volume situations. Now, there’s good feedback (the violent but musical sound of, say, Jimi at Woodstock) and bad feedback (an obnoxious squeal that no one but an audio pervert could love).

Unclear on the difference? Let my use my Seth Lover-equipped Les Paul to demonstrate:

I cranked a small combo amp, added a germanium overdrive pedal, and placed the guitar right in front of of the amp. I got a nice wave of controlled feedback, with strong third and fifth harmonics. Yum.

Good Feedback

Then I turned the amp all the way up, shoved the pickups right up to the speaker, and got a blast of bad feedback.

Bad Feedback

Kids, don’t try this at home, unless you want to be looking for a new home. My apologies to my ever-indulgent next-door neighbors.

But basically, I believe feedback fears regarding unpotted pickups are greatly exaggerated. I encountered no bad feedback problems, even with a high-gain overdrive pedal and a maxed-out amp—I really had to go out of my to make the pig squeal. It’s hard to imagine anyone encountering serious trouble when using a vintage-style amp, even if they dime it. But yes, if you’re performing in front a large modern amp on the burn channel, you could get ugly shrieks, especially if you have a lot of guitar signal pouring from your onstage wedges as well as your amp. If that’s your style, you should definitely play potted!

14 comments to To Pot—Or Not?

  • DohminSemper

    I recently brought a guitar with active pickups on a rehearsal with my band, and the feedback was sooooo bad on a 15watt amp, even on the clean channel that I had to turn it off after every song we played.

    • joe

      That doesn’t sound right, does it? What kind of guitar and pickup? I’m not an active pickup expert, but I can check with the Seymour Duncan guys who are. Pickups of that type should be feedback-resistant even at extreme volume levels.

  • I’ve used the standard EMG and Seymour Duncan actives countless times and have never once seen issues with feedback that severe. I’ve also used cheaper Guitarheadz active pickups and again, even with cheap models, I’ve never seen that. Actives are not potted with wax but rather sealed in epoxy. I’d look at the circuitry on the guitar. My guess is the feedback is not resonant but rather caused by some sort of short.

    I do know that active pickup can amplify noise created by poor wiring in the home. As an example, the home I live in right now has knob and tube wiring thats very old. When my kitchen light is on and I’m playing an active guitar, the guitar buzzes like hell through the amp. As soon as I turn the light off, the buzzing goes away completely. The electrical switch is not shielded and due to the old wiring, it causes interference.

    Since i just play guitar to annoy the television, I just deal with it and keep the kitchen light off.

  • joe

    Like I said, it’s not my area of expertise. But from talking to the Seymour Duncan guys, I know they engineer their Blackouts-series pickups to work well under insane performance volume levels, because, well, some of their signature artists perform that way. It really should be pretty hard to get them to feed back like that.

  • Interesting thoughts. These days, in general, I’d say pot everything because there is just too much amp out there!! I only have a 30 watt Cube and a 15 watt Fender Pro Jr. (Most guys expect i have Marshall 50 watt half stack at least for some reason). Why anyone would need a 100 watt amp today with direct line outs, cab emulation, etc….I don’t know.

    I can see the tonal value of the unpotted pups. Wouldn’t make a difference for anything I play though. And maybe the trend towards smaller amps will bring more unpotted pups back. And as I said, one guys shows up with a Triple Recto or Mode Four….oh well.

    Just for fun – take a half full large beer can, push it hard against the strings/pups, then talk into the opening. Put it through some distortion, maybe a flanger or a wah. THis will work with potted pickups. Way more fun than just talking into an unpotted pup!

    • joe

      Hey Aceman — thanks for the thoughts. Yeah, that’s a great question about why people use huge amps. Really, they were designed for a time when P.A. systems were extremely primitive, and the amps WERE the P.A. I understand that some folks really do prefer the tone of those huge amps, and no disrespect to them. But truly, there is no reason you can’t play any venue, no matter how huge, with an amp of any size. You really can play stadium shows with modest amps—trust me, I’ve done it. The comic part of the equation is the acts that perform in front of a wall of amps, but rely on a single offstage speaker for their tone.

      Here’s a hilarious story one of my guitar techs told me: He was working with a big British band, though, principled fellow that he was, he refused to specify who. The bass player INSISTED on having his bass cabinet miked, even though the front-of-house sound guy and everyone in the band insisted that the DI signal sounded better, and that the loud bass cabinet onstage made the show much harder to mix. “But that’s my tone!” he insisted, and refused to step onstage unless there was a mic on his cabinet. So each time he walked onstage, there was his miked cabinet. With the mike cable running offstage and out of sight. Where it was plugged into (wait for it) . . . a cabbage.

      Regarding the potting: All things being equal, yeah, potting is better. But things aren’t 100% equal, and I really, really, really love the sound of my unpotted Seth Lover pickups. 🙂

      I am SO going to try that beer can trick. If I can find a beer around here that’s still half-full…

    • Dirtbagg

      Aceman you are so special 😉

      But I agree, unless you are playing Dodger Stadium or huge outside venue, 50 watts is more then plenty.

  • Was the cabbage true bypass?

  • I bet they used a cabbage patch cord!

  • I guess the cabbage was head, not a combo?

  • Lettuce try to stay focussed here, the tone of the cabbage is the important thing.

    • joe

      Sounds like you love that story as much as I do! The tech in question was such a gent — no matter how much I begged, he refused to tell me who the band was.

  • Nuno Carmona

    Tone fiend,

    have you tried to use the pickup as a megafone but with an uninstalled pickup away from any metal material? Was the result, the same?

    Best regards

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