Feedback noise on a preamp

[Jevil]

This question is already asked on the Peavey Rockmaster thread but few people own it so few have answered.
Anyway, I have a second hand Peavy Rockmaster than sound really good but when I turn volume up - quite loud- it starts a feedback annoying noise.

The preamp is connected to a Peavey Tube Poweramp and even using a PodXtPro as gate that fucking noise keeps on sodomizing my ears everytime I stop playing.

Could it be a problem of tubes or what?


PS. I mean by feedback to that sound when you put a mic close to a speaker. That's the correct word, isn't it?

 

[Metaltastic]

Sounds like it could be your tubes being microphonic; it's cheap enough to replace 'em anyway (I have a Tung-Sol in V1 and Chinese 9th gen in the rest in my JSX and love it), so you might as well

 

[Jevil]

Had no idea about "microphonic tubes" but you are right Metalstatic. I will have to change them all.

What is a microphonic tube?

If a tube is "microphonic" it will "howl," or feedback, like a microphone. No tube is free of microphonics, and some say that a little is actually wanted for a livelier sound. Microphonics are caused when the insides of a tube start to loose their solid construction from vibration. There is no fixing this. All we can hope for is that our tubes are well constructed. (technical explanation of microphonics)

If a tube rings like a telephone it suffers from "filament rattle." Like a microphonic tube it should be replaced. Filament rattle isn't technically the same since the tube isn't acting like a microphone. Often you'll hear people mistakenly identify filament rattle as microphonics.

It's well known that you can tap on tubes to hear if they're microphonic or suffer from filament rattle, but BE GENTLE. You can damage the tube when it's hot. Also, don't use your finger! If you hear the tapping being amplified don't freak out, as said before all tubes are microphonic. Tapping should be reserved for when you know you have a badly microphonic tube, but need to identify which one.