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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
bjesien
1,405 posts
 
What is the efficiency of your speakers? I've used similar ARC amps with 87-94 db speakers and never had humming and buzzing except when it was in the music or connections were bad.
jazzgene OP
145 posts
 
I have called ARC. Waiting for Calvin to call me back.

The efficiency of the speaker is 91db. It's Focal 1027 Be pair.

The amp is brand spanking new from a dealer here in the NYC area.

Cmalak - are you saying that this amp should be dead quiet in the speaker with no hum?
jazzgene OP
145 posts
 
Spoke with ARC. They say the slight hum in the speaker is normal for this amp. However, the published spec states 0.2mVAC with inputs shorted.

I checked it out and the left channel shows 0.7mVAC and the right channel shows 0.25mVAC. I'll have to get to the bottom of this. A new amp shouldn't have nearly 3x more hum in one channel than the other.
bjesien
1,405 posts
 
Have you swapped tubes from one side to the other?
jazzgene OP
145 posts
 
Yes. I swapped the tubes from R to L. Measurements remain the same.

I want to add that the ARC spec of 0.2mVAC with input shorted is IHF weighted. I don't know if it is A-weighted but most likely it is. If that is the case, then my measurements of noise is well within spec of 0.2mVAC RMS.

hmmmm... Any tech guru's out here? What do you think?
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