Low, rumbling, oscillation

[johnnyg88]

Hey guys,

About two years ago I purchased my Electra Dyne 2x12 combo. It was old as it was clear that it had been sitting on the showroom floor for quite some time. It came stock with Mesa V30's.

Anyway, recently, I've noticed that when I play D notes on my guitar (12th fret, D string, 7th fret, G string) it creates a weird, low and rumbling oscillation. This happens in every mode of the amp. Am I hearing damaged speakers or tubes?

Thanks!

jg

 

[YellowJacket]

I would definitely try tubes first. Preamp tubes followed by power amp tubes. Getting one new one and swapping it out, one by one, with other tubes should narrow down the problem. The fact it is in all modes indicates that if it is a tube problem it will either be a preamp tube that is shared by all modes, or it will be a power tube. It may be another problem, but test the tubes first before starting to worry like crazy.

 

[elvis]

Could be a microphonic tube. Tube-rolling might spot it.

I'd try PI first, those things seem to cause all kinds of mischief...