Question About Biasing KT66 Tubes


I am attempting to bias a tube amp for the first time and cannot find much information on biasing KT66 tubes. My amp is a Antique Sound Labs AV25DT, and I biased the tubes to 550mv based on some random google searching I did, but I'm not confident that this is correct.

How do I know what to bias the tubes to?

After spending some time with a tube amp designer, I found that they will play with the bias voltage at times to achieve a "sound", sometimes at the expense of tube life. Ergo I would suggest that you find the voltage that the designer/manufacturer recommends.
The KT-66 is rated at 25W, the operating range being from 12-18W. You need to know the plate voltage. A Compu-Bias would greatly help. Mcdonald43 is correct. Check with the amp's manufacturer about the bias setting but also ask him where in the power range the tubes are operating at that bias. Good luck.
Thx for the responses. I tried emailing ASL, but they did not reply. I am going to do some trial and error work to determine what sounds best and will report back.