Tube microphonics in a preamp


Hello

I just installed some Amperex 7308 white labels into my Blue Circle BC 21.1 preamp. They sounded wonderful right off the bat but exibited some microphonic (tinging and ringing) through the speakers when I changed the volume or even touched the surface of the unit. THis was not apparent on listening to music. Now that they have had about 30 hrs on them, the microphonics are gone. Normal phenomenon? Have the tubes gone bad now or have they broken in. I don't notice a big degradation in sound quality...I've probably gotten used to them. Would YOU keep using them? Thanks. Dave.
canucks0

Showing 1 response by dogpile


I've experienced the same ringing problem with a couple of my Amperex 6922's from the preamp section over a period of time but decided to remove and replace the microphonic one...the "howling" was just too unbearable.

It's peculiar that the "tinging & ringing" from your tube(s) just went away...I would have them checked & tested for leaks just to be certain.