Originally Posted by Robfow
I've just bought this amp from someone. After some listening, I've realised that there's a hissing sound that comes on in the right channel every minute or so. I'm wonder if any of us have this same problem as well?
This is likely to be tube noise. To diagnose:
1) Exchange the gain tubes (the one in the window and the one closest to the front on the side). If the noise changes sides, you need to replace the noisy tube. (Note, check the tubes to make sure that the ones you're exchanging are the same tube type, just to be sure).
2) If Step 1 didn't find the tube, exchange the output tubes and listen again.
If the sound switches sides on one of these steps, you've located a tube to change. If the sound stays put, then there is likely to be another problem that's going to be harder to find.