• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

new 6080 dc pp

This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Is it your design? It's an interesting concept.

I want to get some advice or ideas before I go.

To drive the output tubes all the way to full power (Vgk 0) the current through R3 and R4 will need to reach 0mA. This in turn means your driver tubes need to reach cutoff for max power. There are a few ways you could avoid this and give the driver some more headroom.

Regarding the screen arrangement. If you do NOT intend for it to be used as negative feedback, it is fine as-is. But if you intend for it to work as negative feedback, it will not be effective when significant value resistors (R2/R5) are used between the screen and feedback signal. That is because the resistance buffers the screen from the feedback signal allowing the screen to do what it wants. Adjusting R9 will adjust gain in any case because your adjusting the screens AC load. If you do intend the screens to be used as negative feedback, you can lower the values of (or remove) the screen resistors if you tie them to the opposite side of R12/R14 where your DC voltage is lower.
Last edited:
Would you mind reposting that schematic
as .asc.txt attachment or .asc inside .zip?
Best, zipped with needed .inc files too.

Why does this forum still not yet recognize
LTSpice file types as safe and legitimate
plain text attachments?

Valid file extensions: bmp doc gif jpe jpeg jpg pdf png psd txt zip

Hard to simulate circuit from a .PDF
Last edited:
I sim 25mA difference between V2 and V4.
Same issue appears true for other side of
the circlotron, V1 and V3.

Do these stacks represent voltage doublers?
If so, 25mA DC in each power secondary.

If both power transformer secondaries are
wound on the same core, you could phase
doublers so DC magnetic imbalance cancels
on opposite swings. But then OPT might also
hear this activity as hum. Phase for quietest
hum, and power transformer core sees twice
the DC.

Maybe 25mA DC per secondary is nothing to
worry about? But you asked for observations...
Last edited:
Each 60Hz half wave, the other power secondary sees an extra 50ma (average)
load. The difference between them is AC hum through the output transformer...

If you phase so the higher current half wave is simultaneous in both halves of
the OPT, then the power transformer DC imbalance does not cancel.

I'm thinking doublers must phase for hum cancellation in the OPT. Bleed resistors
across less demanding V2 & V3 can restore DC balance in the power transformer.
Last edited:
I am going to make one like this View attachment 194147
I want to get some advice or ideas before I go.
Many Thanks in advance.


Interesting OPT Circlotron Amp Topology,buy must say with interesting but too complicated PSU arangement,think the Real PSU behavior well be the bigger trouble maker for normal AMP operation.Any way continue with Your experimentation,who knows....Wish You Luck

Sory for my limited & bad English language
Ok,admit that PSU is not so complicated,but You have to try to realize this interesting Circlotron Variation circuit in Praxis,Spice is only Spice- only good for Virtual probes and Circuit analysis, and `Spice` usualy dont Lie, but for final Amps Sonic judgement only merit well be jugde of Your(Listener) Ears.;)

BTW The best way for Circlotron OPT arangement is so called `Split bobbin coil` OPT.Any way, any Tube Amp OPT is allways part of Sonic degradation.
But with Circlotron PP based output stage,OPT is litle less Critical than in other Tube Amps topology and sonic degradation is less,but not totally removed.

Best Regards SS :)
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.