Tube bias question

[BlueChiaro]

As a tube newbie, I have a very basic question: Should a signal be fed to the amplifier during the bias adjustment? I can't tell from the owner's manual, and I don't know if it would even matter, but I thought I'd ask. Thanks, in advance...

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[Face]

Unless the manufacturer recommends it, no.

[BlueChiaro]

Originally Posted by Face

Unless the manufacturer recommends it, no.

Mike, the exact quote in the ARC manual is:

Amplifier should be turned on and operating for at least 30 minutes prior to adjusting bias on the output tubes.

It then goes on to explain the process, so I really don't know how to interpret that. I did it without a signal the first time.

[cmalak]

Robert...no signal is fine. Just have it on for 30 mins before adjusting bias and then once adjusted, I would play music for a couple of hours and then stop and check the bias again on all the bias pots (each bias pot should control a pair of tubes in your Ref 250s). If there is no bias drift, you should be good to go. If there is, I would readjust and then check it one more time after about an hour. If all stable, I would check it again in a month or two and then after that I would check bias maybe once every 6 months. Hope this helps.

[BlueChiaro]

Thank you, Cyril...I appreciate the rundown! Thanks to you, too, Mike...forgot to say thanks in my initial reply.

[Removed]

Many tube amp manufactures recommend never to run tube amps without a load from the speaker.....it can hurt the trannies, doesn't matter if your just idling the amps or biasing them, sources need not to be connected. I would check with the manufacture for your particular amp.....

[PHC1]

Robert, I recall the 250's muting the signal anyways when you push the bias button. I don't think it matters one way or the other.