Microphonic from Vacuum Tubes?

Thanks @atmasphere for your instructions.  The problem is that I think I've heard the pop from either left and right channel before, but not at the same time.   So the problem doesn't seem to be specific to a single channel.

I sure hope that this is not an issue with my Cary preamp.  I've had enough problems with it since I bought it about 7 months ago.  😀

@xcool Like I said, don't make any assumptions. Right now it sounds like you need to sort out for real which channel its in or if its in both.

If its randomly in both, FWIW I'd be more suspicious of your source... but keep an open mind. That's the first rule of troubleshooting. The second is not to make assumptions.

I would start by pulling and reseating all the tubes (rectifier included) when the amp/tubes are cold.

If the popping persists replace the new tubes with the old ones.

If there is no popping after this systematically swap in the new tubes one @ a time.

Aside from a bad tube poor pin/socket contact can cause the noise you describe.

This will take time, but it's easy.

DeKay

Thanks @atmasphere ​​​​@dekay.   My hunch right now is the preamp or the tubes are the culprit.   That's because I've never had any issues with my system before the introduction of the Cary.   

This is probably going to take a while to track down because it doesn't happen that often, and I can't really reproduce it.   I think I will start with putting the old tubes back if I hear the pop again, and go from there.  

Thank you all!

Microphonic is amplification of a microphone like source.  Tubes AND other electronics can exhibit this behavior. Good luck finding a pop source. Static electricity can do it, the dry season is coming.