New Weber Bias Rite and new KT66s

[Slammintone]

I got a matched pair of Shuguang KT66s last week and installed them yesterday after the arrival of my new Weber Bias Rite BR with the V1 option. Plate voltage for one tube was 477vDC and the other one was 481vDC so I set the bias at 36mA allowing for 70% max plate dissapation of the KT66s and let the amp cook for about an hour and a half and the bias had dropped to 33mA and 34mA so I brought the bias back up to 36mA and installed the tubes directly into the amp. (I'm going to give the tubes a full 10hrs extra burn in time today) Then I plugged my new Historic R8 Iced Teaburst Lester in and wow, the amp suddenly has it's mojo back and then some. No more hardness or ice pickyness when cranked, now I got smooth thick creamy distortion and much more of it (think EC and the Bluesbreakers, or better yet Mick Taylor and the Bluesbreakers with a touch of Paul Kossoff) than I had when any of my other KT66s were biased much too hot at 41-43mA. The tubes themselves now have the proper soft warm glow and sparkle when running and PT doesn't seem near as hot to the touch either. And here I thought you had to overbias to get more distortion. What a misconception. Now it makes sense why the amp had more distortion when I was running EL34s biased at 34mA. Without knowing it at the time I was already there at about 70% and as I recall the amp distorted and had a overall tone close to as good as I have now. At lower volumes the amp sounds like a really good just breaking up Tweed Bassman. In a 4x12 I'm sure it would nail AC/DC crunch no problem. I'm am much happier with the sounds I'm getting outta the amp now but 480VDC?? We'll see if these tubes will last through summer and maybe fall and then I'll probably leave the PT alone and install some NOS Genelax KT66s. If the tubes fry out due to the onslaught of plate current then I'm getting a replacement PT and will have it installed at that point. I'll report back how things look and sound after a better break in.