Quick Filtering Q:

[surfsup]

I cascoded the 6sn7 input which I figure will draw around 10mA total. So my B+ nodes should be ~400 on the EL34 plate, ~340 at cap2, ~300 at cap 3 (putting about 210 on the plate of the 12ax7 w/100k) and I am hoping ~325 on the 6sn7 node.

Is the filtering going to be okay with a 1k/22u on the input stage?
What do you think of the EL34 plate at 390-400V?

[VacuumVoodoo]

See EL34 data sheets for class A SE.
TFK triode & pentode modes page 1: http://www.mif.pg.gda.pl/homepages/fran ... e/EL34.pdf
Mullard pentode mode page 1: http://www.mif.pg.gda.pl/homepages/fran ... e/EL34.pdf

[surfsup]

Vacuum, I had been looking at the graphs already, thanks though. I was worried with the plates at 400V and the filtering R drops about 50V due to larger current draw of the 6sn7 (10mA, 2ma, 8mA for 6sn7, 12ax7, screens) = ~20mA so 20mA*2k7 = about 50V).

I think I'm good now. And updated the schemo for a 220R on the cathode of the EL34 to drop 12V with 58mA current. With the screen sag I needed a 880R so the 1K should be fine.

[VacuumVoodoo]

What graphs I directed you to tables on 1st page in those sheets with typical operating conditions for EL34 SE class A with a 3k OT. No need to stare at graphs

[Tillydog]

[img877]http://chicagocadcam.com/ChrisHahn/supr ... oded_2.jpg[/img]

I think you should review where the left hand end of C6 goes to before you build it (V2a is a cathode follower, right? - sorry if I've misunderstood.)

Andy (aka Tilly Dog)

[surfsup]

Tilly, damnit drawing these things in a graphics program is such a pita...overlooked that thx, corrected.

[img877]http://chicagocadcam.com/ChrisHahn/supr ... oded_3.jpg[/img]