Help Vox Valve Amp Making Bad Noise ???

Tommytwopence

Hi,

I hope someone can help. My Vox AC30 is making a 'quiet' feedback noise which stops when the amp is gently kicked but starts up again after a few minutes.

I've owned it for 4 years and I think the amp is about 16 years old. Can anyone help diagnose the problem and suggest a fix?

owwdatune · Posted: Sat Nov 25, 2006 7:58 am Post subject:

sounds like it might be time to check your tubes. Cool

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Tommytwopence · Posted: Sun Nov 26, 2006 1:42 am Post subject:

Sorry, rather new to this. Any advice on how I check the tubes and what to look for?

T

Herb · Posted: Sun Nov 26, 2006 7:37 am Post subject:

Without a tube tester, about the only test I know of you can do at home is to check for microphonic tubes. Turn the amp on with nothing plugged into it, warm it up and turn it up so you can hear hiss fairly well, then lightly flick each tube, if you hear a "ping" or a "thud" coming out the speakers, the tube is making noise and needs to be replaced. Preamp tubes should be replaced regularly, and power tubes from six months to two years (this is just a general rule of thumb, depends on the tubes, the amp and how hard the amp is used).
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