Megatron Electrostatic Headphone Amplifier

[JoaMat]

Schematics auto switching. Not sure it's accurate, but that's what I've done.

New Grid Voltage Control boards.

One trimmer for offset and the other for balance so, both sides are controlled simultaneously. Two jumpers. For 300B/2A3, EL34 and EML 20B-V4. Works al right, quite easy to use.

The -510V is achieved with help from GRHV 110V supply. Here is one with Hammond 2VA trafo on board - 2.75in x 2in. 
 

New idea - servo controlled grid voltage.
Okey, I've tried servo controlled Megatron (with solid state CCS) before and that failed...

[kevin gilmore]

better put a 300v zener across the output of the h11d

 

[JoaMat]

Thanks a lot.

I've been thinking of a 300K resistor cross the h11d to limit the upper grid voltage.