Hey guys, I've got a weird question. I know this is difficult to diagnose without hearing it, but my Fender Twin Amp has this weird metallic sort of rattle when I hit certain notes. At first I thought it was a speaker going out, but it is distinctly metallic sounding. I can't seem to find it. It's definitely physical rattling and not the speakers, as placing a 2x12 on top of the combo and running through those speakers instead of the combo speakers still causes the buzz. The strange thing is, I played a gig last week with a band whose guitarist was complaining about the exact same type noise from his Orange combo, also when he hit certain resonant frequencies.