DrKev
Wholenote
It's just a guitar, it's not rocket science.
Posts: 416
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Post by DrKev on Jan 9, 2021 4:37:13 GMT -5
I have a guitar student who has just bought a used hand-wried Vox AC4. It's had some work done at some point in time. He has a buzz/hum he doesn't like that goes away when he *removes* the tube shield. Is that indicative of a wiring issue? Potentially dangerous? Or just run the amp with the shield off?
Many thanks!
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pdf64
Wholenote
Posts: 556
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Post by pdf64 on Jan 9, 2021 11:55:49 GMT -5
It’s always good practice to have any newly acquired mains powered equipment checked by someone competent, especially so with guitar amps, where the user will be constantly touching its electrical circuits (via the guitar strings, unless using a wireless connection).
But the symptom seems really weird, I can’t think what might be causing it. The best I can come up with is that some sort of shock mounting arrangement has been added for the valve socket, which then has left it electrically isolated from the chassis ground.
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DrKev
Wholenote
It's just a guitar, it's not rocket science.
Posts: 416
|
Post by DrKev on Jan 9, 2021 12:56:25 GMT -5
Thanks for the reply. When I get chance I'll check that out. (With COVD number as they are were teaching online so I have yet to see the amp).
We had a chat about it during our lesson this afternoon. It sound like it might be a microphonic preamp tube and the microphonics are very much worse when the cover is on. Possible I guess? Anyone experienced such a thing?
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Post by Leftee on Jan 9, 2021 14:17:07 GMT -5
It’s worth a tube swap to see. But I’ve never seen that.
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