Se Kt-66

[MartinV56]

Hi Guys, My next project is building a SE KT-66 . I have several KT-66 Penta and some Russians 6L6. I think the Z1 for 6L6 and KT-66 is = 4.5-5K. I am among these three circuits accept and appreciate their suggestions, Thanks

[MartinV56]

Mikael Abedella with 6DJ8 or

[MartinV56]

Thanks, Martin

[kenpeter]

The third schematic may appear Pentodes in Pentode mode.
But wired as illustrated, cooperating as-if one very big triode.
I would expect it to sound more like a Triode than a Pentode.

Do not be tempted to bypass the 50ohm beneath V1, it is very
necessary to V1's function as voltage controlled current source.
To tickle V2's feedback network without screwing with its ratio.

The plate to plate to B+ network is pure RCA-Schade-1938 /
Fetron style triode emulation. Repairs or Replaces the broken
or missing "4th circuit" intrinsic feature of a Triode. Fixes what
happens when you stick constant voltage screen in the middle
of a Triode. But still let you have the screen tied to B+.
If I like it, surely something wrong you should stay far away.

All of these simple designs (as drawn) do not have good PSRR.
You are going to need a very quiet power supply.... Might I
suggest you also look into Loftin White. Its a deep and tricky
subject I know, but rewarding if you can fathom its mysteries.

[Salas]

This one looks OK to me.

[MartinV56]

Thanks guys, Pentode road