Interested to know what your bias readings are and whether you have experimented with alternate values.

TIA

Hywel Harris

You are referring to power tube biasing, I think. If so, then I can say that the Tung Sol 6L6s that Nik supplied, sound the same to me anywhere from 25 to 35. I keep them at 30 based on my amp tech's advice. I am currently running Tung Sol 5881's at 35-36mA. They sound fine, I think I like them a little better than the 6L6s. I have been wanting to try some TAD 6L6WGC-STRs  (short bottle like the 5881s). They were my favorites in my super reverb, very musical, nice sparkly natural overdrive, not the most clean headroom. I biased them at about 35mA in the SR but it was running close to 500 volts (and they only lasted about 6 months). I would try them at 30-35mA in the OTS. My experience that that bias does not effect tone except near the extremes of the range and if you operate out there you are burning up tubes or damaging other components.

I've got my Winged C's biased at 37~38mA.  Headroom is good, but I run the internal trimmer low & keep the clean volume around 7.5.  OD Vol & Ratio is set conservatively, too.  I live on the OD channel with my Gretsch & OD + PAB with my Les Paul.

At 235v wall voltage I get a plate voltage of 449 v.
My bias setting is 38 mA with Tung-Sol 6L6 GC str. I bias my amp after 15-20 min when voltages are not fluctuating any more due to heat in the amp.

I experimented with 30-35 mA it's too cold, less harmonics, no singing notes.

40mA is over the top; the bass response is way too heavy with that setting.

Tung Sol 6L6 GC

455V on plates 36mA last time I measured.

I use to have it a little higher but I dropped it a little and it sounds fine to me.

What I've always been confused about is the fact that no matter where you set the bias, when you are actually playing through the amp the bias current is jumping all over the place. While it is recommended to set the bias at 70% maximum plate dissipation for that tube, you still will occasionally exceed that 100% max plate dissipation value during actual operation of the amp.

I would give Bob at Eurotubes a strong recommendation. His tube matching is consistently impeccable. His recommendations have always been right on. I have spoken to him in person a couple times and believe tubes and customer service are this guy's life. He is so busy that the last thing he would do is mislead somebody to sell more tubes. That said, I can see no reason to bias that hot, even if Bob says its OK.

Tube amp doctor 6L6WGC-STR @ 37-38 mA