What were they thinkin' in this old tube PA

[Sweetfinger]

I'm working on a 1940's to early 50's Operadio(Dukane) PA head. It is similar to this schem at triode electronics:

http://www.triodeel.com/du1a45a.gif

Mine has just two mic inputs, 2 6L6's, and a 5V4 rectifier. I've replaced all the electrolytics and it powers up and sounds pretty good with a guitar. The thing I'm wondering about is R15 on the schematic. In my amp, its a big chorkin' ceramic wirewound 10K that connects the screens to the cathode on the 6L6's. It just seems to me like i'm throwing away some power here. The first dropping resistor in the power supply (2K in mine) is also a big ceramic and it heats up QUITE hot indicating a fair amount of current. Any thoughts?

[Bruce / Mission Amps]

And I've seen those resistor cracked and burned open in those amps.
I don't care for that method either.

It's just a way of loosing a bunch of B+ so the screens are not as high B+ as the plates.
It is a B+ voltage divider (R15, R16 and the cathode biasing resistor, R17) and an AC bypass from the screen to a very low impedance ground point.

Measure the voltage drop across the resistor and divide that voltage by the resistor value and you'll see how much current you are loosing in the B+ rail to that circuit.

[loudthud]

Your amp was designed for a very early version of the 6L6. The 6L6G has the same ratings as the metal 6L6.

Max plate volts 360
Max screen volts 270
Max plate watts 19

With this in mind, it was probably cheaper to use resistors to reduce the screen voltage than to have more transformer windings, another rectifier tube and filter cap.

I think the 6L6GC was the first version to have a 30W plate rating.