Old used Peavey Heritage series 130w tube amp buzzing from the back, not the spe

Question:

Old used Peavey Heritage series 130w tube amp buzzing from the back, not the speakers--why???

Had it since Christmas, did not notice this buzz before. Buzzes even with speakers disconnected. Loud playing drowns it out, but is it something wrong? Bad tubes? Never had a tube amp before and not sure if that is the problem or something else. Buzz does away if you play a while, comes back if you stop.

Best Answer - Chosen by Asker: sounds like a fly w/ a megaphone? welcome to owning tubes and why they were later engineered out.

when tubes get hot, they buzz. keep them dust free also and this will help alittle.