[sdiy] sort of OT: The virtues of solid state bridge rectification vs. tube half-wave rectification

[anthony]

I have a nice, big HV transformer from a piece of tube gear that used solid
state rectification of the full-wave bridge type. The HV secondary is 300V
with no center tap. I'm sure it can handle a lot of current because it
served as the B+ supply to about 20 tubes, 4 of them EL84's pulling voltage 
regulator duty, but mostly
twin-triodes.

I am planning on using it in a push-pull amp using 2 EL34's that I want to
bias purely Class A. I always forget how to figure out what the final
rectified and filtered output would be based 9on the P-P or RMS voltage,
whatever. I had a thought that bridge rectifying the 300VAC would give me a
voltage too high to run the amp purely in Class A. But then I haven't really
run the numbers on EL34's, except to figure that one of the filament
windings (there are 2 6VAC filament windings with no center taps) will work
for 2 EL34's if it worked for 4 EL84's.

Anyway, now comes my second idea: I have this big 9-pin (noval? whatever the 
non-mini 9-pin base is...) damper
rectifier, a 6DW4B, whose specs seem stout enough (unlike the 3A3 that I 
looked up too). Wouldn't the half-wave
rectified voltage ultimately be lower than with a solid state bridge?

I've run a few configurations on Duncan Amps' PSU designer software and this 
does seem to be the case. I think I'll need a separate filament transformer 
for the heater on this though, since one winding will be just for EL34's and 
the other one for the 12AX7's.

So I suppose my question is: is there really any mojo in using a tube 
rectifier in a more or less 100% Class A push-pull amp. I remember reading 
something somewhere to this effect, but I can't remember what. I tend to 
ignore claims made by boutique shops trying to sell you some $1000 amp with 
cloth insulated wiring for that vintage tone only cloth insuylated wire can 
give.

cheers,
aa