Audio Research I/50

the question is why if it has automatic bias , you still have to bias it "by a trained technician to ensure proper operating values."
something is contradicting here ?

That is probably after you install a new tube-set.

i'm planning to ask the distributor here to check this subject with ARC

Interested to hear.

@dweller The manual says "Upon replacing a power tube or tube set, the I/50 must be biased by a trained technician to ensure proper operating values."

@stone1 Where did you read that the I/50 has auto bias? I can’t seem to find it anywhere. May I just missed it. Thanks.