Tubes Asylum

RE: microphonics woes

63.247.1.2

In Reply to: RE: microphonics woes posted by Ethanh on May 28, 2007 at 07:55:42

Ethan,

You know, what you describe may not by microphony. It almost sounds like electrical instability or some sort of wierd positive feedback.

Are you able to check the plate voltages and current draw on those 12AX7's? For some odd reason maybe the front end is running the tubes too low plate voltage or not drawing enough current thru the tubes (just a guess). Anyhow, my experience is that if the nominal values have fallen out of the ballpark (especially if signal tubes are run too "cold"), the result can be a pulsing or "whoosing" sound.

Besides, chances are both 12AX7's did not go microphonic, at the same time.

Follow Ups:

RE: microphonics woes - Ron Oehlert 07:59:49 05/29/07 (1)
- RE: microphonics woes - Ethanh 09:58:07 05/29/07 (0)

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