I changed the cathode resistors on the 6L6s to 820R and was able to drop the current to 45mA, is it my imagination or does the amp sound better? Cathode voltage is now ~28 V. Since my last post the unit has about 20 hours on it and seems to be sounding nicer as a result of that as well.
350 V is low for 6L6, however the tube is not designed for ultralinear and I wouldn't want to risk meltdown by running the screen grid too hot. I'm thinking about a tightly regulated supply ~250V for G2, this way I can give the 12AX7s a solid supply and run the 6L6s at 450V without worrying about fireworks. Lighthouse Electric has a switcher @ 250V. Eliminating UL will increase distortion and if I don't like it, can run EL34s, which are designed for UL. Eventually I would like to try KT88s, but I think I will wait for the Eiclone and fixed bias. I like the look of the 6L6s, and KT88s are even more impressive, they give the amp an air of authority that 6BQ5s lack.
I have read a couple of times now of attatching G2 to B+ through a dropping resistor, 1500R seems a common value. Since G2 draws current, this resistor gives it the lower voltage it needs to survive. The drawback is that power supply sag will cause a substantial drop in power with a corresponding increase in distortion. The question is: Has anyone tried using a resistor between the UL connection and G2? Any ideas what effect this might have on power and distortion?
AFN Don[/i]