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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: Re: Now you've got me scared! posted by Ozzy on July 25, 2002 at 07:47:30:
RD,Rotate the 12AU7 into different positions. Do the same for the 12AT7's. My bet is if the microphonic tube is in the first gain stage---getting it out of that stage and substituting a good tube will resolve much of the problem.
If, after all the maneuvering of tubes DOESN'T resolve or at least lessen the problem, you'll need to look for cold/broken solder points. Dried out caps (especially ceramic disc babies). And possible instability or oscillations in the gain stage/PI.
I'd try to first rotate a KNOWN good 12AT7 and 12AU7 into the unit. MOve it around to the vaious positions and see if that helps. It would be a lot less hassle if the culprit was a loosey-goosey tube.
Certain 12AT7 and 12AU7 are kinda noted for microphony. Probably one of the reason why so many "ruggedized" versions of each tube exists.
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- One more suggestion... - steven oda 08:15:02 07/25/02 (0)
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