For the CCS in the front end, it is good to have at least 20V to dictate operation where the capacitances have stopped changing due to delta-voltage. Too much voltage requires troublesome heatsinks.

The supply uses a 30VAC input to a voltage doubler. Two CRC stages, one full voltage, and the other from the midpoint and also dropped through the decoupling resistor.

One could also terminate the two supplies with chokes. From Mouser, a 6.8, or 10 millihenry high current choke ( J.W. Miller 5800 series, PN 542-5800-682 and -103 ). They're $1.48 each. For the cap, a good film or film/foil unit. The ASC X387 of 7.5 or 10 uF from the bias pot wiper to ground will do nicely. The split-CT grid chokes need the two center ends AC coupled to ground anyway, and this cap is a very good choice there.

More drawings to come...:)
cheers,
Douglas

The unloaded AC voltage of the supply TX should be very close to 30. AC voltge * 2 * root2 needs to be always less than the PIV of the diodes used. There are Schottky of higher voltage, so uprating is fairly easy.
cheers,
Douglas

Good work! May I suggest a schematic for bias pots?
Pots are 100k/lin, (50% on the scheme just means that program needs % of "opening" the pot...); in the middle position we have about -65V out.
Resistors R2 & R3 (between the wiper and "input" leg of the pot) are not necessary, but it`s a precaution if wiper gets discontinued. The useful range is about -50...-80V.

For valves like the 1619/1624 or triodes like the 2A3, some makers suggested inductive coupling to ground. Either the secondary of an IT or a grid choke. For a pure resistive element would load the previous stage too much.

Hence Galahad, with its 10k plate load. Even a 2A3( which seems to accept over-spec grid circuit resistance values ), a 60 or 70k might be a better idea...:)
cheers,
Douglas

What does the sentence negative rail supporting front end current mean?

good to have at least 20V capacitances have stopped changeing due to delta-voltage?
Why are the heatsinks troublesome?

Thanks; if this kind of questioning is not productive let me know.
The rest I understand.

On heatsinks, anything is a bit ov a pain compared to bare TO-220's for me. But I am a bit on the lazy side. It shows everywhere: simple PP circuits, simple linestage circuits...nothing too complicated anywhere...:)
cheers,
Douglas

• http://www.audioroundtable.com/GroupBuild/Projects/Galahad_Bias_Doubler_Schematic.pdf