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RE: Serious Micro-Phonics and Hum from Citation V

Posted by Jim McShane on July 7, 2012 at 14:35:58:
For a moment let's assume you haven't made a wiring error, and it is likely that if there had been a hyper-microphonic tube in there that it's not there now.

And I can be 100% sure the kits are not at fault, there are hundreds of them out there working great.

Of late there have been some cases reported of problems related to output trafo issues. There have been a few cases of oscillation as well as various other issues. But the likelihood of it happening in BOTH channels is fairly low. Does the amp make the noise from both channels or just one? I don't mean which one you are tapping, I mean does the noise come out of one or both speakers? And is this the amp that had the broken internal connection that you and Mike Samra sorted out?

Next - we'll now assume a wiring error could be at fault. It is not difficult to hook up the output trafo wrong - especially since after 50 years the wire colors have changed quite a bit and they are difficult to sort out.

Check the heater voltages on the tubes too - especially the 12BY7As.

Let us know what you find! We'll continue from that point when you reply.