6C45 SET spud

[e_fortier]

Before spending any cash I'll listen to the 6C45 a little more, so far the highs are a bit aggressive compared with the Darling or ACA (no pre-amp used with these two). Maybe it's my friend's pre-amp. Must check all this first.

Thanks everyone
Eric

 

[needtubes]

The Darling is such a laid back amp, so that's not much of a surprise. I have also built both amps - Darling variant and 6C45 spud - and like both. The detail of the 6C45 is nice.

 

[audiowize]

I too had a little parallel feed Darling and a CCS loaded parallel feed 6C45 for use with headphones.

(The 6C45 is still here, the Darling got sold)

 

[e_fortier]

It would be nice to see your operating point, Va, Vk, Rk, some use 10mA bias while other find their sweet spot at 40mA. I haven't built the one in my first port, I just draw the schematic. I might try some Cree Schottky diode instead of Rk

 

[audiowize]

IIRC, it's set for about 25mA of current and 1.5V of bias with a CCS plate load and a 5K:150 output transformer. It's currently setup with a cathode resistor/bypass cap combo. The LEDs that I would want to use won't be so happy with that kind of current passing through them.

 

[e_fortier]

Thanks

 

[e_fortier]

Just received the small transformers from Edcor, Phyllis provided amazing service (as always).

Just want to verify the wiring to prevent blowing my DAC...

I connect the output (1 of them) from my DAC directly to pin 1,2 (2.5k) and then pin 5,8 (10k) to the input of the amp.

Pls confirm even though it's a basic question.

 

[PRR]

...DAC directly to pin 1,2 (2.5k) and then pin 5,8 (10k) to the input of the amp....

Yes.

 

[e_fortier]

Thanks PRR

 

[papparazzi]

I use PSE 6c45 Spud driven through 10k pot ,220vdc over tube ,2.5k load and 90 ohm cathode res each tube with 1kuf bypass . So about 25ma per tube Gain is littlebit small ,yes but in right speakers no problem . Of course voltage is much over recommended 150 vdc but sound is better with higher voltage . I tried cheap input transformer and also GG type preamp . I solve gain problem ,but loose special sound character with more gainstages

papparazzi

 

[e_fortier]

Final schematic

Despite it's low cost the sound of this transformer is quite transparent. I have increase the overall gain of the amp without using SS components, that was my goal .
Thanks to all for your help.
I'm attaching the latest schematic with the added transformer.

BR
Eric