Thanks Miles!
Your posts are always insightful. Pentode is fine really. Just a toy to play with while I buy parts for my bigger amps.
Maybe 3.3-4K / 60W Edcors for a pair in pentode?
Forch, I saved all the original notes. Loadline (attached) Do keep in mind that this particular project never got built, so it's very much a preliminary design.
With an Rl= 635R/phase, you'll need ~2.54K (P-2-P) A 3K3, 60W Edcor should be just fine here, and the somewhat lighter plate load will drop the output a bit, and maybe the distortion as well (though it doesn't look like you're gonna get very much of that anyway).
Even though these H3 estimates are rough, and high-side errors, they
do correlate somewhat to sonic performance. However, in the final analysis, you still have to spend some time listening to the open loop performance to see how that distortion sounds, and what's likely to be necessary to correct for those sonic defects. If the 6CB5 is like the 6BQ6, all it'll need is enough gNFB to take the "edge" off. There shouldn't be any of that "pentode nastiness".