Amp feedback troubleshooting help

[src248]

Hello, I've got a Traynor YGL2 that keeps making a high pitched feedback sound. After having the amp "fixed" three times with no luck I figured I'd try here. It sounds kind of like normal guitar feedback but worse and happens with or without anything actually plugged into the amp. It's definitely worse on the drive channel but can still be heard on the clean channel. Changing the amp settings occasionally has an effect but usually doesn't change anything. The noise stops while a note is being played but comes back as the note fades. Any help would be appreciated, thanks!

[VinceT]

Re: Amp feedback troubleshooting help

Have you switched out the tubes?


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[src248]

Re: Amp feedback troubleshooting help

Have you switched out the tubes?


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Yes, it seems to fix the problem for a few hours but then the sound comes back.

[Mincer]

Re: Amp feedback troubleshooting help

Strange, I started hearing this high-pitched sound tonight on my Mesa (1 channel, no master volume). I wasn't somewhere where my replacement tubes were, so I didn't get chance to swap them out.

[VinceT]

Re: Amp feedback troubleshooting help

Yes, it seems to fix the problem for a few hours but then the sound comes back.

OK. That suggests it’s not a microphonic tube. Some other diagnostic questions:

1) does it do it with multiple guitars?

2) does it do it in multiple locations? (E.g. live venue, home, etc. - checking that it happens on different power sources)

3) is this happening with guitar straight into the amp (no pedals, even turned off) and nothing in the effects loop?

Also, if you could get a sound clip of it happening - even recorded on an iPhone, it would help us help you.


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[src248]

Re: Amp feedback troubleshooting help

OK. That suggests it’s not a microphonic tube. Some other diagnostic questions:

1) does it do it with multiple guitars?

2) does it do it in multiple locations? (E.g. live venue, home, etc. - checking that it happens on different power sources)

3) is this happening with guitar straight into the amp (no pedals, even turned off) and nothing in the effects loop?

Also, if you could get a sound clip of it happening - even recorded on an iPhone, it would help us help you.


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Guitars/cables make no difference, it still happens if the amp is on without anything plugged in. The only other place I've had the chance to try it was at the guitar store when I went to get it fixed and we couldn't replicate it there, so that does seem probable. I've tried it through a voltage regulator at home without luck.

https://youtu.be/IDOfm3O6-8o audio sample

[Myaccount876]

Re: Amp feedback troubleshooting help

You want to try and isolate the source of the sound. Start pulling tubes (other than the power tubes and phase inverter - you won’t get sound with those pulled). If you’ve pulled all the preamp tubes, leaving just the PI and power section, and the squealing goes away then you know it’s in the preamp. If it stays, then it’s coming from the power amp. If it’s in the preamp, remove one tube at a time, and if the noise disappears after pulling any one tube, then you know the noise was coming either in the circuit before that stage or the circuit immediately at that stage.

[Darg1911]

Re: Amp feedback troubleshooting help

Is this you?

[src248]

Re: Amp feedback troubleshooting help

Yeah, that's me

[Darg1911]

Re: Amp feedback troubleshooting help

Just a guess but maybe some type of oscillation. I'm not sure how to go about fixing it though. I know, not helpful at all. Sorry.

[VinceT]

Re: Amp feedback troubleshooting help

Listening to both vids, it doesn’t sound anything like tube feedback to me - if anything, it sounds like synth-type oscillation (literally like the sound generator in classic analog synths) which would suggest the circuit board and internal components.

I just went looking and found this thread. Different amp, but there’s a good description of why it happens.

https://www.ultimate-guitar.com/forum/showthread.php?t=1278543

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[src248]

Re: Amp feedback troubleshooting help

It's so inconsistent that it's hard to actually figure out what's doing what. I was getting the sound almost immediately after turning the amp on, tried removing the preamp tubes, wasn't getting the sound. Put the tubes back, still wasn't getting the sound. Played for a few minutes and it came back but it isn't coming as easily/quickly anymore.

[Myaccount876]

Re: Amp feedback troubleshooting help

If it plays fine but starts acting up after a few minutes it could be an overheating issue. I’ve had overheating carbon comp resistors start making weird noises. Not saying that’s definitely going on with your amp (they might not have used carbon comps or anything like that at all), but overheating is something to consider.

[src248]

Re: Amp feedback troubleshooting help

Update just for closure: amp seems to be working now, tried all kinds of things but it may have just been overheating. I stopped putting it on a stand and am keeping it away from the wall, sound hasn't come back after many hours of use. Thanks for your help everyone!