Hi guys! I just changed my preamp tubes a week ago and everything was fine!

Now after a couple of minutes playing the amp, there's a fading in low noise that comes from my amp. A loud low noise.

What the heck is happening?

Thanks a lot!
Could you further define 'low noise'? Is it a persistent tone? Could be a ground loop.
I'll post a clip of the sound when it will come back. Now the amp is fine but 5 minutes ago the sound came in. It was a loud fuzzy sound and I couldn't hear my guitar anymore! It happened all of a sudden!
LOL you call that a low noise? it would make my brain melt if that happened to me!

I hope you fix it soon (Im no help sorry!) great amp you have!
merry christmas
First check the seating of the valves and give the sockets a clean.
If it were me I'd be looking at the signal on a scope. If it is 120Hz then I'd replace the filter caps.
It doesn't sound like an earth loop.
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