If it's a constant popping sound I would bet it was one of the preamp tubes and not the power tubes. I'm not familiar with that amp, but do check those as well. If you swap in your other set of power tubes and the noise persists its an even better bet it's one of the smaller tubes in your unit. I hope I'm right as those NOS EL34 Mullards had to be pretty spendy.
Popping from tube integrated amp
I've owned an Eastern Electric M520 for about 3 years and have it connected to Omega Hemptones. I changed the EL34 tubes about three months ago from the stock Chinese tubes to NOS Mullards.
This afternoon about a minute after powering up the amp, very loud popping noise came through the speakers - - the popping was constant - about 90 to 100 pops per minute I would guess. The volume was at a (loud) constant level, regardless of where I set the volume control. The popping continued without regard to which input I selected.
After turning off the amp, I reseated the tubes and tried again - - same popping. The tubes all look normal - - no unusual visual cues.
Anyone have any idea what the problem is likely to be? Many thanks for any suggestions.
This afternoon about a minute after powering up the amp, very loud popping noise came through the speakers - - the popping was constant - about 90 to 100 pops per minute I would guess. The volume was at a (loud) constant level, regardless of where I set the volume control. The popping continued without regard to which input I selected.
After turning off the amp, I reseated the tubes and tried again - - same popping. The tubes all look normal - - no unusual visual cues.
Anyone have any idea what the problem is likely to be? Many thanks for any suggestions.