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Reverse connected Futterman (sometimes called the Technics futterman)...It yields the lowest output impedance of any topology that I know of. I considered 6C33 tubes last year in the design/prototype stage (I don't think I found a type better electrically suited to the task), but abandoned the idea because I could not find a remotely reasonable price from any source that had some...From what I've read they used to be cheap and plentiful, but are now scarce and costly.
I was able to achieve +-60V output supply rails with a 60V secondary of a transformer, a doubler circuit, and a lot of filtering....The only problem was the transformers and the grid bias circuits tended to sag under load. I have plans to remedy it with beefier transformers I have laying around, and linear regulators which should arrive within the week.
If you have a decent amount of tube and SS power transformers on hand it is doable to build a supply from junk....The only difficult part is finding a beefy enough filament transformer for most output tube compliments. 6AS7 tubes use 2.5A @ 6.3V so my unit takes 11A @ 12V from 2 12V windings of a transformer whose secondary windings are composed of wire thicker than the wiring in the walls of my house.
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