"Bob"

IIRC, impedance is turns ratio squared. That would mean that he should
tie the "4 ohm" tap to ground instead of the 8 ohm tap. I would
presume that he wanted the same voltage levels (but 180 degree out of
phase) on both cathodes).



** Correct - the posted ( hypothetical) diagram is wrong on that.

http://www.nashaudio.com/Public/6550_OUT.pdf





.......... Phil