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First Test for tube bias on ARC Ref 110?

When is the appropriate time to first test biasing on the ARC Ref 110?
This is my first experience with a ARC amplifier and I have read that power tubes typically drift most in the early stages. What is meant by early stages? Any recommedations are appreciated. It has only just under 49 hours of use thus far, so far from even broken in yet...
bavarian05
bavarian05 OP
65 posts
 
I have to agree that auto bias is a very convenient feature, but I think it slightly hampers overall transparency. I have also owned the Primaluna Prologue Two and then upgraded to the Dialogue Two (both with KT-88's) and both are lovely amplifiers for the money involved, but after comparing to others in relatively similiar price ranges (Rogue, ARC's integrated) I could definitely hear a more transparent sound in those without auto bias. These differences could potentially be many other things, but on first glance, that is my assumption as to what differs between them electronically. This is not meant to put down Primaluna in the least, again, they are great amps, though I think you pay a small price for the ease of use with auto bias.
bavarian05 OP
65 posts
 
70 total hours of running in so far, I just checked tube bias for the first time on my Ref 110 and three of the four sets were running just a little bit low. Should be at .65mv according to ARC manual and they were running around .61-63mv. I assume this is a very minor/mild drift. I adjusted the three sets that were slightly low back up to .65mv and away we go... I will check again at 100 hours. This was my first time biasing an amp, and I found it to be kinda fun!
marakanetz's avatar
marakanetz
5,473 posts
 
Cmalak,
Why do you thing that it's done by "added microprocessors and digital circuitry"?
1. Autobiasing is done in DC domain and does not affect the signal no matter what kind of components are being used vacuum, solid-state or ICs.
2. Autobiasing could also be done without using any "added microprocessors and digital circuitry" by common cathode resistor(1940's?), but modern means of autobias widely implemented in Quicksilver amplifiers not only save tube life, but apperently improve sound! Stable quiescent grid current is a "dream:" of every tube push-pull amp.
Pardon, but I don't see this as convenience only feature.
cmalak
681 posts
 
Marakanetz...I guess we will just agree to disagree.
marakanetz's avatar
marakanetz
5,473 posts
 
Yup,
Why not? Autobias will substantially decrease tube demand on the market. Microstrip speaks nothing but the standard marketting words to make an amp cheaper.
How much the price of the unit will increase by introducing common Cathode resistor or few semiconductor elements(modern way)?
This makes the unit plug-n-play with bullet-proof reliability that substantially decreases demand to send the unit for repair.
I explained facts and not opinions or judgements.
For next upgrade try to get Quicksilver's flagship and experience the magic along with bullet-proof reliability.
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