It seems every tube amp I've ever owned that I really liked had a similar problem. I always assumed it was bad tubes, or tubes rattling. There is this buzzing or sort of ringing sound that resonates with a certain note or a few when played, and turned up loud. I returned a crate palomino, which sounded really sweet, because it had this problem, years ago. My blues jr had this issue but I found that I could dampen the noise by stuffing a block of wood between the reverb tank and the power tube retainer. One thing all three of these amps have in common, are el84 power tubes.
But it seems worse on this vox.
I tried replacing all of the stock tubes with new JJs. It definitely improved the tone and I think made the amp louder as well. But the buzzing is still there, maybe even worse, but resonating with a different note, a higher one. To be honest, it's really bumming me out, because I love this amp, but it sounds like crap when it makes all this noise.
I didn't want to have to pay somebody to go through it but I may have to. Could it be a capacitor? Or something else? Anyone encounter a similar problem and find a solution?
I'm beginning to feel I should just sell it to somebody else and let them deal with it, and get one that doesn't have this issue.
I've tried tapping on the tubes with a pencil, before I swapped them for the new JJs, and I found nothing too unusual.
It seems though that one of the preamp tubes, where its socket is attached to the circuit board, the board bends a bit, and that tube seems more susceptible to noise when being tapped, but especially if I tap the circuit board above that tube. That makes me wonder if there is some issue with the circuit or the socket there.
Any tips would be appreciated!