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Manual vs. Auto Bias

In considering new directions in which to take the evolution of my system, I have run into conflicting claims as to which results in less distortion...auto or manual biasing, according to what product(s) the so called expert manufactures and/or represents...(Surprise!) How about some input from average consumers like myself who have had more experience with one or both?
anjowin
marakanetz's avatar
marakanetz
5,473 posts
 
More over I'd say that if I ever go back to tubes, I'll make sure I'll buy an auto-bias amp or if price is convincably low for fixed-bias unit, I'll DIY implement it(most-likely with SS parts for less space and money).
rockadanny
1,224 posts
 
Not sure why the discussion of auto bias vs. fixed has come about since the OP is seeking info on auto vs. manual bias, where neither is fixed. Anyway, my manual bias amps also have the soft-start feature, which certainly is good to save tube life.
metralla
945 posts
 
Manual bias adjustments here with a 2 minute soft start (Lamm ML2.1).

Need a decent true RMS voltage meter (I use a Fluke) and one has to make adjustments to both plate voltage and current on each monoblock. The measuring jacks and adjustment pots are right on the top, with the required values written adjacent - very easy access. It's a ten minute job and the drift over time is small. It's not a problem.

Regards,
wolf_garcia
6,695 posts
 
Tube auto bias circuits are SO cool...I wish they had 'em in guitar amps. They get rid of an issue I've always had with high end tube amps.
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