It is SE actually since the bottom driver tube is backward-powered. You loose lots of power on phase-splitting transformer that is 15K:600 Ohm. And to get full advantage from GU-50 tubes in pentode mode you need no less than 600V of B+. I use 850V in my Pyramid amps getting 80W per channel.
It is SE actually since the bottom driver tube is backward-powered.
My mistake - I forgot to flip the tube, I will redraw the schematic.
... And to get full advantage from GU-50 tubes in pentode mode you need no less than 600V of B+. I use 850V in my Pyramid amps getting 80W per channel.
I have the same experience. In my Bass Amp with 6 GU50 I have 950V of B+ (Idle), the resulting output power is 320Watts. Schematic is attached for info.
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I have the same experience. In my Bass Amp with 6 GU50 I have 950V of B+ (Idle), the resulting output power is 320Watts. Schematic is attached for info.
Hi,
what's the plate-to-plate impedance of your OPT?
Best regards!
Raa = 2K, a little bit lower than the optimum of 2K7
Ok, thanks!
2k7 would be according to the Telefunken EL152 datasheet, p. 9, last column.
Best regards!
Interesting, but the GNFB loop is very long now IMO, 3 tubes, 2 transformers and a capacitor. That's a long journey to correct any errors..
My solution is/should be to limit the feedback to each half of the amp (the push and pull phase split sides), but I'm not sure how good that will be for crossover distortion.
Like the interstage in general BTW, very nice!
My solution is/should be to limit the feedback to each half of the amp (the push and pull phase split sides), but I'm not sure how good that will be for crossover distortion.
Like the interstage in general BTW, very nice!
Have you continued you work on this amp? Would love to hear about your experience and results.
That was one of the version. Triode straped GU50 in PP. The front tube was 6350 and the driver 12B4A. The output transformers were 14K:8. I made a mistake when ordering transformers - thats why 14K:8. The power was around 18W. The sound was good. Realy good. Excellent bass.
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Matejsirk
Did you ever build this circuit you posted last year? If so, how did it sound?
No, I did not. It is only simulation in LTSPICE. I have 6 sons and almost no time. Maybe in the future.
The output transformers were 14K:8. I made a mistake when ordering transformers - thats why 14K:8. The power was around 18W. The sound was good. Realy good. Excellent bass.
So, what's the impedance of your OPT?
Thanks!
And this is my last version, not finished yet. I am still waiting some material.
I do like your (optical) design very much! Looks really, really cool to me.
Congratulations!
Ulrich
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