Bias Question

[mikeg]

I just finished a 5F4 clone from mostly on hand parts from 20 years ago when I used to do a bit of amp repair. It works beautifully and sounds terrific but has a bit more headroom than I imagined. After checking the bias etc. The tubes( 18 year old Groove Tubes)  are dissipating 19.06 and 18.46 watts. If I understand it correctly they're not supposed to exceed 16.1 if grid biased?  My question is which of the two resistors would it be best to change, the 6.8K or the 56K or both? I looked at the variable bias layout also on this site which shows 470 ohm and a 10K pot with 27K to ground on one leg of the pot. This doesn't seem like it would work for this application for a variable set up?  I'm sorry if this has been covered I did a search and haven't found these specific answers. Thanks very much for any help offered!!!

[PRR]

> more headroom than I imagined

I don't think I have ever heard that on this forum.

> not supposed to exceed 16.1 if grid biased?

Why?

19W is hot for original 6L6. You don't have, can't accidentally get, real original 6L6. Since ~~1960 about all "6L6" are on the 6L6GC frame, good for 30W on paper, maybe 24W in real life, conventionally biased near 20W-21W in guitar work.

I think your job is done.

If you truly want cooler, decrease the 6,800r resistor. 1K will make it way-cold and probably "hoarse in the soft parts". (You can tack-solder 4.7K or 2.2K across the existing 6.8K to see the difference quickly.)

With "only" 410V on tap, I would not bother with variable bias on this classic old plan.

[mikeg]

I copied a chart from YouTube video re:biasing that stated that for grid bias you should go down to 70% of the cathode bias rating. Maybe I have the terminology wrong what I mean sound wise is the amp sounds terrific but stays clean until it's deafening. At least to an old geiser like me. HAHA! I was under the impression that if I could get the plate dissipation down a bit( tubes running colder) it would break up a bit earlier. Thanks very much for answering my questions. I wasn't sure which resistor to tweak.

[mikeg]

Just to clarify, I forgot to mention I didn't want anything that broke up as early as a 5E3 Deluxe. So I definitely got that but expected it to break a bit earlier than it does. But frankly I'm fine with using a pedal as the tone is real sweet as it is. Thanks again for the help.