Hey, I've been searching online for a few hours now and I still haven't found any sort of answer to this problem. I've got an Ampeg B4R that makes a loud buzzing noise as soon as it's cut on. It doesn't matter if anythings plugged in or not, and volume and tone adjustments make have no effect on it. I've tried different basses, speaker cables, cabs, power cords, and outlets. I'm at my wits end. Has anyone figured out the solution to this problem?