I know its not my amp because I've tried different basses on the amp and it doesnt crackle. Its a small Rumble 15 amp and the bass its crackling on is a MIM Fender Precision bass. Whenever I play a note it crackles ALOT and very loud. I've messed with all the knobs on the amp and bass. I think it might be these two springs that were under the pickups that came out when I was replacing some screws but i doubt its that.