Microphonic from Vacuum Tubes?

HI,  I have a question regarding microphonic from vacuum tube.  I have a Cary SLP-05, and I've changed the output gain tubes to some NOS RCA, and also recently purchased a pair of Linlai for the balanced buffer stage.

I now occasionally hear a loud pop in the music.   It doesn't happen very often, but when it does, it is quite loud.   This happens when I am streaming digital music, so it can't be those occasional pops you hear from vinyl.  

Can someone tell me if this loud pop possibly caused by microphonic in my tubes?  if so, how do I track down which tubes?   My guess there is no easy way but change one tube at a a time, which can be extremely time consuming.   Also I don't own a tube tester.  I wonder that would help tracking it down.

Also I read something about vacuum tube damper rings,  would that help calming down possible microphonic?

I still  consider myself a newbie in tubes,  so any hep will be appreciated.  Thanks very much.


@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.



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.


If its randomly in both, FWIW I'd be more suspicious of your source...

I was wondering about that myself, but I don't know anything at all about streaming.  Do you have a CD player you could run for an extended period of time to see if it pops with that as your source?  If it didn't, I would think that would point to the DAC or something else in your streaming chain.