[bartas]

What can I say... WOW!
There is no looking back to the original cornet 2.
I can not tell what is the major contributor to the sound, choke power supply or 6SN7 buffer but the effect is not subtile. Comparison to the original is irrelevant.
The circuit works with some small adjustments. Increasing second PS cap made a big difference, thanks poty!
Really happy with the results. Thank you Jim for great circuit with so much potential in it.

[flocchini]

Bartas:

Would you mind posting the schematic of what you actually ended up using. Kudos to you, poty and all those that participated.

I originally built my Cornet2 with the 6Sn7 and have been thinking about a choke supply. The mod to the 6SN7 section may be frosting.

Thanks

Bob

[poty]

My best congratulations Bartas (if it is possible to say this way)!!! You are the hero. It's great you have made it works and works great.  I'm hungry for the resulting schematic too!

P.S. It's amazing how quick you obtain the chokes! I'm here, in Russia, still waiting for all the stuff to begin with. It seems USPS and Russian post have arguments about my parcels! And the most often linked sources for the parts (digikey for example) is almost unusable in Russia because of huge delivery cost. So it takes a lot of time to even start the experiments!

[bartas]

I will post the schema, just have to steel some time to make the changes. Still feel that will be experimenting with PS capacitance a bit.
The chokes came from Finland http://www.uraltone.com. They have stock of Hammond products and shipping via Tellia is excellent.

[bartas]

This is what`s on now.
I got rid of everything not necessary in the circuit. This is the schema as it is executed.
I haven`t changed the output cap/resistor yet and C203/R207 filter. I hope this isn`t upsetting Riaa equalization. I have no caps of sufficient quality at the moment for these changes.
The overall gain is a bit less than stock cornet 2 but only slightly.
Any comments are very welcome.

[flocchini]

thanks for posting

[poty]

The schema is not changed a lot!
It seems you have dropped the bleeding resistors, but the thing which puzzled me most is R221 1k8 resistor in serial to plate voltage! Why did you decide to add this?
And why there is 10K resistor to the plate voltage for the first two stages? As soon as the plate voltage for V200 and V201 haven't changed (according to your measurement - only small 3 V increasing) and the cathode resistor is the same value, it should be 0.75 mA current to each stage, like in the original schema. So the 120k gives us 0.75*120 = 90V more and total 123+90=213V of B+ for the first two stages. (215-113)/1,5=1k3, but not 10k! Or the original schema values was completely irrelevant?

[bartas]

I went for Jims SAKURA values on V1-2 plates (120v) so had to adjust the resistors. Current now is 0.6 mA. And for V3 I tried to reach 10 mA point or 90 trough the tube and 125 cathode.

[poty]

Trying to analyse the possibility to build the same layout for the new Cornet. But I'm thinking about inverted phase since you have changed the last stage.

[bartas]

What do you mean?
Are you planing to go for balanced output?

[poty]

No, it doesn't related to balanced things. Just the signal in the output has 180 grad phase relating to the input.

[GRD]

Poty,

How did the last stage change?  Looks like a cathode follower (no phase change).  So I'm missing something.

Thanks,

Grant

[poty]

Grant,
You are absolutely right. It's my mistake - looking through so many schemes, so forget about each already! 
Regards,
Poty