New Crack build--- is tube sound pickup/microphonic action normal?

[PharmaCyclist]

Hello all,

I just recently finished building a new crack and really enjoyed the kit.  I will post a thread with pics soon.  In the meantime, I've been doing some listening and just now noticed that the Crack seems to pick up ambient thumps/physical impacts and amplifies them-- is this normal?  It doesn't seem to depend much at all on how high the volume is set and the background is otherwise silent with my source paused.  I am using an isolated source from an external DAC.  I can actually hear the spoon hit my cereal bowl in the amp when I eat from it on the desk.... that's how I first noticed it!  The Crack tested and seems to sound fine.

[Paul Birkeland]

This is referred to as microphony, which can be an issue with random tubes in tube gear.  It isn't anything abnormal or harmful, and with some tubes it's completely unavoidable.

You may find down the road that when your tubes wear out, their replacements won't be as sensitive.

-PB