guitar screeching at hi gain?

[chuckb]

I currently just had a new pick-up install in my les paul and I have some screeching problems . it occurs on a higher gain settings and it sounds so unnatural. are the pick-ups wired improperly or could they be faulty/ any help would be greatly appreciated.

Chuck.

[denitronik]

Sounds like the pickup is microphonic, some of the parts are vibrating at high volume.
Do you know if the pickup has been potted by the manufacturer? If not, you should have it potted (dipped in a mixture of bee's wax and paraffin).
You could do it yourself, there are many examples on the internet (YouTube).

[tedmich]

YEAH!

\m/ \m/
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oh you don't want the screech?....sry

[big_teee]

+1 for Pickup Potting.
What brand and model pickup?

[Paleo Pete]

Yep, sounds like potting is in your future. Not that hard to do, I just used some commercial kitchen type wax used for canning, in a little fondue pot I think it is, kind of a miniature crock pot. Attach it to a wire through an adjustment screw hole, drop it in, wait till it stops bubbling, pull it out and clean off as much wax off the top as you can before it hardens. Worked like a charm, no more screeching.

How To: Pot Your Own Pickups

GuitarNuts.com - Potting Pickups

One thing the guitarnuts link points out that's good to pay attention to, don't remove the tape around the windings if your pickups have it. I also think it's a bad idea to try and dip them using the pickup wires, I put a 6 inch wire in a screw hole to do mine.

[Mark Hammer]

Given the nature of the question, the OP likely doesn't have rich knowledge of the inner workings of pickups. I don't mean that as a diss. Rather, if he's gonna fix things safely, he needs a little more info.

A pickup is essentially a wire coil, wound around a magnet. You can generate a voltage by "disturbing the magnetic field" via nearby string vibrations. BUt you can also produce a voltage by moving the magnet itself, OR by keeping the magnet stationary and moving the coil.

Whenever any of the windings around the polepieces or slugs (in the case of HB bobbins) are loose enough to be shaken by loud sounds, that IS essentially, moving the coil around the magnet. It may not seem like much but can be enough to produce a small voltage. If loud enough - and especially if aided by anything that maximizes sustain, like a compressor or high gain clipping pedal - those windings start a-shakin at whatever their resonant frequency is and keep shaking, producing the "screech".

Potting involves physically stabilizing them so they can't shake. Lots of substances can be used for potting, but wax is generally preferred because it can penetrate the coil and hold the whole thing steady, because it's cheap, because it's easy to apply and hardens relatively quickly, and because it is easy to reverse with a little bit-o-heat. People will swear by various types of wax, vacuum devices to draw the wax deep into the coil, etc. My own experience is that the wire at greatest risk of being loose is generally on the outside, so a bit of wax applied to the outside 10% can often be enough to keep things in check. Soaking right into the middle IS probably better, but it seems silly to have a big setup for the sake of one pickup.

Note that the "loose turns" can also be the wire ging from the solder eyelet on a Fender-type coilform to the outside of the coil. That is, the source of the problem can sometimes be something VERY accessible, and undeserving of a major intervention. In an instance like this, it can simply be sufficient to take a dab of clear nail polich and secure that loose wire to the flatwork. Where it is simply a couple of turns on the ouside, I've had good luck with taking some teflon plumber's tape and applying a few turns over top of the coil to hold everything tightly against the side of the coil.

IN other words, sometimes the problem can be tackled by means other than full-tilt potting. Potting is always better, but we're looking for good enough, here.

Depending on the pickup type, and the source of the microphonic, there can be a little risk in disassembling the pickup to take care of it. The worst-case scenario would be PAF-type humbuckers, where two coils have to have their outside covering gently and carefully removed. Depending on the age of the pickup, the adhesive on the tape around the coil may have decomposed a bit. This will require extra care during the unwinding, so as not to tear the wire on the outside of the coil that goes to the wire lead that will eventually work its way to the switch and controls.

Once yu have been able to expose the outside of the wire coil - safely - you might consider applying some of the teflon tape, which will conform nicely to the outside of the coil, and allow it to be pulled rather tightly without tearing or damaging anything. Alternatively, for single coils, I've lain them on their side, held a candle about 8" above, and used a heat gun on low setting to melt the was, which will drip down and seep into the coil. Once you have the wax on the coil, a gentle application of heat will allow the blobs that hardened the moment they landed to liquify and seep in more thoroughly. You can wipe up the excess with a tissue, while the wax is melted. Rewrap, re-install, and you should be good to go. In the grand scheme of things, it's not that hard.

If you reach a point where you're not sure what to do, stop, come here, and ask, before continuing.