A) I like the idea of the split rail B+ concept. If I am using a stereo PPUL design, would one rail be enough to feed one pair in PP, or should each tube have it's own supply (i.e. 4 rails)?
B) This question will show how green I am.........Which Impedance value do you match to the primary of the OPT? (Rl(a-a), or Zout) And in a tube data sheet, when it lists these values under a PP pretense, is that the combined value for both tubes?
You can just split it after the first choke like I did on my 300B amp. a-a measurement on a PP transformer is the anode to anode resistance so yes that is for both tubes. Z out is the speaker impedance i.e. 8 ohm.
I just thought about it for a second and realized that in PP the B+ goes to the CT of the Primary. So I suppose that a single split rail system for PP stereo would be correct?