Gibson LP Jr's feeding back .

[Len Biglin]

My customer has a lot of experience and is touring , he is having trouble with his Gibson les Paul Jr's feeding back , they would be less than 10yrs old , maybe 5 . One is more prone to f/b than the other . I cant say Ive had this problem before with P90's , my 1st thought was to wax pot them although they are probably already potted , or maybe to float them more loosely from the body ? Any ideas please ?

[Joshua Levin-Epstein]

Even if they are potted, they might not be potted well (I'm avoiding any reference to "well potted"). Some people think potted pickups sound different than non potted so beware. Tap on the pickup to see if its microphonic. 

The pick-up should be tightly mounted, which isn't tricky with a LP Jr. We've all heard humbuckers rattling in their rings. You might make sure the lead is not rattling against the baseplate or the cover rattling against the top of the pick up. If your customer is playing loud enough to cause feedback (wanted or not), you want make sure the only thing shaking is the string.

[Len Biglin]

Thanks Joshua , They didn't appear to be waxed so i potted them both for about 15 min  till no more bubbles , but I couldn't tell any difference . One fedback on a harmonic of the A string and the other on G string , and if i got a foot from speaker they both chirp , amp on 10 . P90 has a big coil so maybe they need longer in the wax . The wiring goes straight down to back cavity , i think I'll try some sponge rubber under them .

[Walter W Wright]

"One fedback on a harmonic of the A string and the other on G string"

you mean the string was feeding back? like you could grab the strings and it would stop?

that's not a pickup defect at all, that's the guitar "taking off" and that's fun!

if you mean that you would grab the strings and the pickup would still squeal at certain pitches then yeah, that's an issue. your goal after waxing them is to mount them as rigidly as possible to the guitar so they don't vibrate on their own. also check the screws underneath holding the bobbin together, make sure they're all tight

[Len Biglin]

Thanks Walter , you are right . I saw both types of feedback when testing , all I can do now is check the screws underneath and mount solidly .

[Walter W Wright]

OK

remember though, the "feedback" of the strings themselves sustaining from the amp volume is not a defect at all, don't waste time trying to "fix" that