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Old 19th March 2009, 11:18 PM   #1
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Cool 2A3 power adjustments by channel

I have a custom made 2A3 power amp--- nicely made but lately I seem to notice that all my music seems to sound louder on one channet than the other--there is no balance knob only volume...I have put in 10-12 cd's and they all sound high on the right channel----is this where I need to adjust the bias? JD
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Old 19th March 2009, 11:32 PM   #2
rdf is offline rdf  Canada
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It would help to know something about the circuit and the history of the problem. Do you have any details?
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Old 20th March 2009, 08:43 AM   #3
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What kind of bias is there - fixed, or cathode ?
You must measure:
If fixed.....Ugrid on the 1 grid of tubes, and measure anode current. Results must be the sames.
If cathode....Ucathode resistor. Anode current for each tube = Uc/Rc. Results must be the sames. /50-60 ma apr. per channel/.

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Old 20th March 2009, 09:54 AM   #4
Tweeker is offline Tweeker  United States
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If the amp is zero/low feedback, one channel could also have more gain in the preamp. Especially if it uses high gm tubes.
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