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Last night I noticed a strange noise from one channel while I let the amp heat up with the source off. Every 20 or 30 seconds give or take the left channel would make a muffled sound for a second or two. The sound is like a muffled pop followed by a faint feed back sound. I was hoping the sound was being caused by a tube failing but now I don't think so. I swapped the tubes this morning in hopes the sound would follow it but I didnt. The sound actually got much louder. I shut the amp down after the first pop because it was much louder in comparison. The left channel socket feels looser than the right so I am a little suspicious of that. Has anyone experienced anything similar? Any advice where to start?

Hi,

That's a common sound in olllllld tube rigs, but not new ones.

I'd look first for a bum solder joint, especially around the tube socket. Also re-dress the socket pins (make them tighter).

Failing that, look for perhaps a defective resistor.

Bad resisitors and leaky caps are usually the cause in vintage equipment, but when it's something new, procedures have to change a bit.

Cheers!

Thanks geek, I resprung the tube sockets and cleaned them with some deoxit and so far that seems to have cleared up all of the noise.

Glad the problem's solved!