A quartet of 6L6GC on top of a 12AX7 phase inverter, signal strength from the bank of tube oscillators was at a sufficient level to drive the amp directly. My aim is to tailor this amplifier for use with guitar, and as such a preamplifier is in order. That's a potential subject for another day, let's just have a look at the voltage supply & power section, as everything else is slated to be changed.
Power supply contains a parallel pair of 5U4 and a choke that would do some damage if it was dropped on a foot. I've found what appears to be a potential candidate for the schematic via search for "Baldwin PC", but it provides little data not already apparent by looking at this thing. I will, for example, have to measure out the choke to determine henries.
Did I infer above that the power section of this will remain untouched? Apologies. That was, in essence, bullshit. The twisted section of 6.3 volt filament pair incoming at lower right is the only twisted pair in the entire amplifier. Lead dress is a nightmare. I theorize that the air core coils at each anode are there to suppress supersonic oscillations that are bound to happen with a rat's nest mess like this. I further speculate that they got away with this due to the overall low gain in the amp. This is a quartet of 6L6, yet I recall seeing reference to an output of only 40 watts or so.
I'm okay with the idea of having a heavy and overbuilt amp for a scant 40-50 watts, I figure the output tubes will last forever here - and if it sounds good I'll leave it be. Of course, when I say leave it be, I mean live with the stock voltage supply and standard component values to support a cathode biased quartet of 6L6. Pretty much everything depicted above will be gutted and rebuilt, and while the spaghetti pile of wiring may have worked fine for many decades I'd like the ability to ramp up power and sensitivity without motorboating.
Another design change I plan on deploying is some variation on a cathode bias balancing circuit such as Blumlein's Garter Circuit so I can "use up" unmatched pull job & oddball tubes instead of saving them for single ended 6L6 amps (of which I think I only have one).