A hum comes out of my amp when not playing (it ain't feedback). It's not the amp. The sound is like the old polarity problems of the old day amps. I have a Epi Jack Casady Bass (hollow body). Never had this problem before with mega other basses I've had in the past. When I bought the bass, the "junction box" was loose inside, so the local "tech" put foam inside through one of the f-holes to hold it into place (he couldn't find where it hooked up). Could this have caused a sheilding problem? The volume pot also needs to be replaced, it will not go to "zero". Don't think this could be the problem.? Bad pot cause hum (and no buzz.. har de har har)? Help!! I love this bass. Blows away anything else I've played, for the price that is.