Hot Rod Deville question

[John]

Looking at the schematic, how did they manage to squeeze 60 watts out of 2 6L6's? I didn't look too closely because it was giving me a migraine    Is there some SS output "help" there as well?


Thanks!

[sluckey]

You posted the wrong schematic in that other thread. This is the correct schematic...

     http://el34world.com/charts/Schematics/files/Fender/Fender_hotrod_deville.pdf

Plate is 485. Those 6L6s must be on the edge of screaming! Look at the note about output test just below the OT...

21.1V RMS into 8Ω load at 5% THD... 21.1²/8=55.65W

[PRR]

G.E. data shows pair of 6L6 making 55 Watts at 2% THD. Last graph shows 70Watts at 7% THD.

[John]

Phew.


Well, I'm not surprised to be surprised. I just recently truly "got" how to calculate center bias to get the most clean from preamp tubes. Of course now it seems dead simple.  Figuring loadlines on pentodes/power tubes still has me flummoxed. Most of my "circuit design" is plagiarism.... err, using other people's research. And trial and error.

[shooter]

Figuring loadlines on pentodes

If you notice, the point PRR refers is at the very end of the "line" after that the tube vaporizes, somewhere in the middle works fine 

[PRR]

> at the very end of the "line" after that the tube vaporizes

No. Look at the Dissipation line. Pdiss falls from 27W at idle to 18W at "70W out". We are doing great violence to the sound, but the tubes are running happy.

[shooter]

Pdiss falls

I did notice that, I figured it was a last gasp 

I'm not sure I ever got a driver tube to put out >75vac before, I know I hit >50
I also know I probably wouldn't like the music