epictring
My Fender Supersonic is making a high pitch feedback after a 2 hr. loud jam session (well... 3 on the volume)
I think it's the power tubes? But like I said, if I were to turn it on now it would be fine, but after a band practice with drums and all the gain channel would start a high pitched feedback noise which you can clearly hear when not playing.
I had a quick peek at the tubes, they're both glowing the same and doesn't seem discolored or anything.
Whatcha think?
greetings
Either a preamp or power tube. Is the Supersonic tube rectified? Maybe it could be that too, I don't know.
AlanRatcliffe
Tap the valves with a pencil and see if any of them ring. If they do, they have gone microphonic and need replacing.
epictring
Cool, I think it's probably a pre-amp tube as the power amp tubes were replaced very recently. But I'll check all of them.
I tried pulling one of the pre-amp tubes out to see whats in it but after removing the metal casing it seemed a bit tight to just pull out, I just wanna make sure if that's the procedure? Just remove the metal case and then pull it out? I was afraid of breaking something when pulling so hard.
epictring
So I tapped all of them a bit with moderate volume on the amp. Nothing.. There's obviously a small "pinch" type sound in the speaker at the moment of impact on the tubes but no feedback like I get after playing a while. Most of the back tubes do however give a seconds feedback noise that quickly goes away when striking, but I doubt it's that.
Gearhead
To pull out, wiggle a little while pulling. I do not know of any tubes that do not come out this way.
Which ones do you mean by 'back tubes'?
epictring
Its weird that its impossible to simulate this at any time. The super sonic has 2 rows of pre amp tubes, I think 4 in the front and 4 on the back, or something like that.
AlanRatcliffe
You have to test it when the problem is there - it's no good checking it when everything is behaving.
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Gearhead
You might be able to pick up which tube or part of the circuit is giving you trouble by switching between modes and using the pre-out power-in loop.
epictring
It's completely fine now, I'll have a look when it happens again.
