2. amps-preamps
  3. 128348-7795

Qs about Bias

I posted it in my other thread about ARC Ref 110 but I guess nobody followed on the old topic since I Didn't see any replies.

After I put new KT120 in my ARC Ref 110 I adjusted the bias after a few hours and again after about 50hrs of play.
Few Questions:
1. when adjusting bias I understand the amp has to be warmed up but also disconnected from the speakers and the pre-amp....is that correct ?
2. The manual says to adjust the main tube to 65mV and only check the slave tube to ensure it is between 55 and 73mV...when I use my digital meter I get to 65mVDC but it jumps between 64.8 and 65.3....never seems to actually stop at exactly 65.0mVDC
3. In addition the slave tubes in the pair always displays negative voltage....and I made sure I use the probes correctly and don't reverse the polarity... so let say I adjust the Bias till I get 65.2 and then check the other tube and get - 60mvDC....so this is in the range but shows reversed current.

Hope to get some clarity on this process....THANK YOU!
ether

Showing 1 response by jea48

jea48
4,319 posts
 

Like others have said the amp needs to be warmed up before attempting to bias.

From ARC Bias instructions:
For best results, operate and adjust the Reference110 at120VAC. Adjustment must be made under zero-signal conditions after at least 15-20 minutes of uninterruptedstabilization time.
http://www.audioresearch.com/ContentsFiles/REF110_BiasAdjust.pdf

If you are/were listening to the amp you need to let the amp set without any signal, music, playing through it for at least 15 minutes so the amp can stabilize. Muting the preamp works good.
.

More to discover