How to know if you have a faulty valve?

AxeWieldingBastard

Im hearing a (background) loose, messy, flubby, raspberry type noise coming from the amp speaker when I increase the gain anywhere above the driest of cleans.
Especially noticeable when chording and striking the bass strings.

Can anyone offer me an internet diagnosis? Or any clues perhaps? Or should i just take it to a tech?

Really appreciate some experienced advice, as i don't don't want to take my amp in to be told i just need to replace a valve

Cheers

ICBM

Could be a faulty valve, most likely (but not certainly) a power valve from your description of the sound.

If you can do this easily, take off the back panel of the amp or otherwise get access to the valves - from what sounds like your experience level, probably best not to if it involves removing the chassis completely or anything else potentially dangerous. It's safe enough to work on an open amp as long as you don't go poking around inside the circuitry, if the chassis is well-supported (eg a Fender Hotrod).

With the amp running, tap gently on each of the power valves with your knuckle. If you get a rumble or rattle noise through the speaker, the valve is most likely the cause. Beware that they're often so sensitive that tapping the other one(s) will often set off the culprit valve, so you may need to hold the one(s) you're not testing with a cloth to stop them rattling as well.

It may still be worth taking it to a tech even for just a valve replacement - if it's a "fixed bias" amp (which confusingly means that it may need adjusting!) it should really be checked and adjusted for any new valves, even if you fit them yourself. But at least, if you're confident that it's just valves, the bill should be pretty small.

If it's a "cathode biased" amp, it doesn't need the bias adjusting so you can just change them yourself.

What amp is it?

Drew_TNBD

Tap it with a chopstick. You can do it a bit harder then, and don't risk burning yourself.

AxeWieldingBastard

Its a Wienbrock ME1 (1 watt/12" spk combo).
Just got it back from being serviced.
There was some snap, crackle and pop noises which have now been sorted. Faulty solder connections apparently.

Now ive got farty, flub noises when playing.

Tapped the vavles and im not getting anything.

AxeWieldingBastard

Will just take it back to the tech.
Hopefully its not serious.

Thanks

ICBM

If it's only just come back from being serviced, it's not your problem anyway - unless it's some new fault that has coincidentally occurred (not likely but possible - unless the valves were changed, in which case it's probably still a valve fault, even if not microphonics) or an old fault which was hidden by the other problem (in which case he should still really have spotted it and let you know at the time).

Sometimes it's just bad luck...

AxeWieldingBastard

Thank you for your help ICBM & Drew.

I think my house is the place where electronic equiptment goes to die.