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ARC VS60 bias

I just rec'd my new ARC VS60 amp and I think it sounds quite good out of the box. The document says the burn in period is like 600hours!

My question is the bias. The amp out of the box shows 65ma. The manual says 60ma. This is my 1st tube stereo amp so I am looking for veterans advice on where to set it. I suppose the tubes will last a bit longer at 60ma and I should use my ear to judge...
jazzgene
stereo5's avatar
stereo5
6,524 posts
 
"I should use my ear to judge... Bingo!
cmalak
681 posts
 
I should use my ear to judge...

Not when it comes to tube biasing. I would call ARC and reconfirm that it should be biased at 60 vs. the 65 it was shipped at. Normally, tube bias will drift with inital use but since they came set at 65 when ARC sent them before use you may want to confirm which is the right setting. Just my 2c worth.
hifihvn
943 posts
 
Voltage variations may have caused it too.Its better to have
it to low,instead of to high.That way it will run cooler,that
is the amp,and tubes.
rrog
1,958 posts
 
Your AC voltage is higher than the voltage at the Audio Research facility. Lower the bias to 60ma as recommended.

This is not something you do by ear.
jazzgene OP
145 posts
 
I went with 60 ma. The music sounds better to me at 60ma as well.

I called ARC. The guy I talked to did not know that VS60 was lowered to 60ma and had to consult a manual. I guess all the older 6550 amps were set to 65ma. So I guess ARC is still sending out the new VS60 set to 65ma.

Anycase, the amp sounds very good.
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