• 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.

Will this supply work?

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Nothing left but final assembly on the 26 pre so it is time to start thinking about the amp it will drive. I’m considering all transformer coupled diff 6CG7 driving 6b4Gs. Since the interstage I have is sensitive to dc imbalance I want to independently bias the grids of the driver stage through the split secondary of the input transformer. I will also do the same thing for the B4Gs

I would also like to use a depletion mode mosfet as a current sink on the tail to force ac balance. So I need a negative voltage for the bottom of the CCS and 2x -35 to -70V 2x -6 to -10v

Modeling the supply as positive with the mess of 50K pots at the end as a single 50K resistor I get 21mV ripple at the 70v tap and 701uV ripple at the bias resistor.

Thanks,
Marty
 

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Thanks for the replies

Could someone please help me to understand what is wrong with the doubler circuit?

It is just a standard full wave doubler with the diodes flipped which I assumed I needed to do to get a negative voltage. I included the choke only to block any HF noise on the supply and used common mode because they are small and inexpensive.

Thanks again,
Marty
 
An easy way to figure out the Henries needed is to divide the load resistance by 1200. Example, 400 VDC@20ma. 400 divided by .02 is 20KOhms. 20K divided by 1200 is 16.66666666666666666666H. This mainly works for a constant load. Also if you notice the smaller the load the more Henries needed.

Craig
 
Thank you both again. Here is a new version with diodes in the correct place and a bleeder to make sure there is enough current through the choke. I also omitted an rc filter section as the big choke really quiets things down in psud.

I get 253uV ripple at the -80 and 1.5uV ripple in the bias stack which I guess should be more than quiet enough.
 

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