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Questions about tubes and gear that glows. FAQ

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RE: Changing the Gain

Posted by Tre' on March 18, 2017 at 19:40:52:
" Gain directly depends on it."
No it isn't.
The mu of the tube changes very little no matter what you do.

Lowering the plate load resistor will limit the max output swing but will not lower the mu (and therefore the gain of the stage) at all.
Edit, I should have said "will not lower the mu enough to make any real difference"
Edit again, Yes you can lower the mu enough to make a real difference but by the time you've done that the plate resistor is so small that the load line is very vertical and the harmonic distortion is unacceptably high.
Bottom line, for all practical purposes the gain of a tube is what it is. If it's to high, get a different tube.

Tre'