Amp Popping and whirring noise

Glaw343

Hi everyone, wondering if anyone can help me troubleshoot an amp? I have a mesa F50 combo and it makes a loud pop about once every hour or two, there's a whirring noise or a bit of a hiss that gets progressively louder and then after the pop it's silent again, the hissing isn't very loud and I only notice it because of the pop and then silence, it sounds more like I have a drive pedal on and plugged in if that makes sense although there is actually nothing plugged in and it does this on its own. sorry for the vague description, I was wondering if this is likely arcing on the tube socket or just a case of worn valves as they are very slightly microphonic (barely noticeable when playing) Thanks.

George.

ICBM

Try replacing each preamp valve in turn with a new one as the first step.

Glaw343

Cheers, I'll order some tomorrow 

ICBM

Glaw343 said:

Cheers, I'll order some tomorrow 

Just one. It won't be more than one that's causing the problem - and it may not be a valve at all. It's just the easiest way to eliminate that possibility.

Glaw343

Ah I see, ok I'll do that, I'm not so bothered about the microphonics as it's not bad at the moment and not doing any recording at the moment anyway. it's the loud pop every hour or so that's a worry, when I was doing some recording the other week, when it popped my interface would sometimes disconnect from my computer, as if there was some sort of surge or something