Audio Research I/50

you have it here , and also found it on other site at the time.
"The i50 also uses an auto-bias configuration, so you will not have to worry about that aspect of vacuum tube operation either."
but of course its not official and things must to be checked.
https://www.tonepublications.com/review/the-audolici-i50-swing/
and here
 

Ah - maybe it was there (lbtech link) all along and I missed it the second time through somehow. Thanks @stone1 

@stone1 The amp from Tone is indeed an I/50, but it isn't an ARC I/50. It's from a company in Portugal. The amp from the lbtech link is the ARC I/50 and the article does say auto bias. I think the author may have jumped the gun when he said all ARC amps are auto bias. I read the owners manuals for all of their current amps and it is true that all of the ARC power amps are auto bias, but the two integrated amps aren't. The VSi75 is user adjustable and the I/50 is not. I'm pretty sure if the bias on the I/50 was automatic or user adjustable it would say so in the manual just like it did in all the ARC amp manuals I've read. I guess when you manufacture a product to a certain price point you have to make some compromises.

Check the manual and get to the installation page.

It said you need get assistance from the dealer or technical guy to get tube bias.

So it is definitely not auto bias.

Besides, they said tube 6550we has about 2000hours. 

And I think it is pretty shorter than normal. But I do not know why.

they say about a technician only when changing tubes.
i agree that it strange that they didn’t mentioned anything about the bias adjustment on the manual.
if it’s no auto or user adjustable it is really bad news.

on the other hand i believe that they aren’t so stupid to produce such a thing that most of the people Will be deterred to buy.
it is something to check carefully.