Amp ringing even when volume is down - UPDATE

[1970]

A problem developed with my rig over the weekend. Amp is a Matamp GT200 through a Barefaced Compact.

Started when I was using a POG for sub Octaves through a muff (for the first time)

when i turned the pedals off there was a ringing sound.

even with the volume turned all the way down on the amp, or pull the instrument out, the ringing is still there.

If I put it on standby then straight back on the ringing stops.

Now using a fuzz pedal triggers it sometimes but not always.

The electricity is the room is known to be on the dodgy side.

Thoughts? Microphonic preamp tube?

Edited October 11, 2012 by 1970

[simwells]

Is the ringing only there when there's a pedal in line?

[Mr. Foxen]

Ding the valves with a plastic chopstick, especially the pre ones, one has probably gone microphonic, and you'll hear the sound coming out the speakers.

[1970]

[quote name='simwells' timestamp='1348151818' post='1810076']
Is the ringing only there when there's a pedal in line?
[/quote]

If I play clean, no probs at all.

Kick the fuzz pedal in and that sets off the ringing (but not always).

[1970]

[quote name='Mr. Foxen' timestamp='1348152347' post='1810083']
Ding the valves with a plastic chopstick, especially the pre ones, one has probably gone microphonic, and you'll hear the sound coming out the speakers.
[/quote]

yeah I've read about this - will give it a shot, thanks.

[quimbymeat]

call the factory

[Maude]

[quote name='Mr. Foxen' timestamp='1348152347' post='1810083']
Ding the valves with a plastic chopstick, especially the pre ones, one has probably gone microphonic, and you'll hear the sound coming out the speakers.
[/quote]


Not wanting to derail this thread, but I use a Peavey Max pre-amp, in the last few weeks I have been getting a high pitched noise all the time from it (if I turn it off with the power amp still on the noise stops and comes back when the pre is turned on), it started as a faint chirruping sort of sound but has steadily got worse and is now pretty much constant.
AFAIK it uses 12ax7 valves, is this likely to be the same problem, I hope it's not fubared as it's an awesome pre amp.

[Mr. Foxen]

Fairly easy to check, plenty else in there to make noises though. Valve changing is easy.

[Maude]

so if I give 'em a tap and the sound comes out the speakers then that one is knackered? I'll check next week at rehearsal, hopefully it's just that, I bought it second hand and I've had it a good ten years so they are getting on a bit.

[Mr. Foxen]

Means its worth changing that one to see if it fixes the problem. In itself, ringing when yo tap it isn't an issue if you aren't in the habit of tapping your valves whilst playing., but it can get bad enough to cause problems, had one new one that was bad enough to feed back on its own when you turned the volume up to sensible playing level.

[1970]

SO as an update (I know you've all been on the edge of your seats). I opened it up last night and wailed on it for a bit until it did the feedback, then started with the tapping.

Preamp valves - went through all of them, no noticable sounds from the amp.

So I set about on the power amp valves - got to the 2nd one and gave it a tap - all of a sudden the ringing stopped. Hm, that's interesting I DID THINK TO MYSELF.

Maybe the poweramp tube was a bit loose and I tapped it back into place? Seems weird but I don't have much more of an explanation.

Put volume and master on 10 and wailed like killmeister for a couple of minutes, threw the fuzz into the mix as well. Then I STFU'd and there was no feedbacking.

Success? maybe so

[brensabre79]

Hope so, sometimes the valve on my Genz works a bit loose with travel and it causes all sorts of thunderous horrible noises. Its a bad mounting design in my opinion, but it cant hurt to make sure all your valves are seated properly.