FC, in looking at that schematic again I now see what you're referring to with the 12AX and 12AU. Honestly, I missed that originally.....I thought that might be some vestige of the 'pre-amp' section and that all that was necessary was the 12AX portion. I'd mention here that I've planned the amp with only 2 driver tubes.....so I'm going to need a driver section that consists of just that. Be it a 12AX, AU, AT, a 'dis-similar twin-triode like the 7247, or a triode / pentode like the 7199, 6GH8, or even a 6AN8. I guess I'll cross that bridge when I get to it. For now, I just want to get the output tubes lit and 'powered' such that it's drawing current. Once that's done I'll worry about what driver design to incorporate. Given this 'glitch' with the need for the AU (or BH7 as you recommend).... I'll probably go back to either the Rowe driver or something else. The Fisher schematic I have uses one 12AX7 per side...... but I don't recall the model. I've seen what appeared to be this same amp with both 12AX7 and 7247s......so, I guess there are some 'Fisher' deviations that one does need to be careful about.