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Old 19th March 2009, 10:18 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, 10:32 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?
Ears aren't microphones.
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Old 20th March 2009, 07:43 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/.

/I remember Eric Clapton's song...."Tulsa time"..../
Projects: OTL-OCL 6AS7 Gen. Electric, SEs 2A3 RCA, 300B JJ, 6S4S, 4P1L, EL11 Telefunken, 6AS7 RCA, 6S33S, 6S41S, 6S19P, E84L Siemens, E236L Telefunken, headphone ampl. OTL Loftin White 6AS7 RCA,... PPs 6005 Gen. Electric, EL34 Mullard, 6L6....
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Old 20th March 2009, 08:54 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.
Be sure your foil hat has a good low impedance ground.
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