Iron Schmitt - low THD phase inverter, vintage too ;)

[Dorin Bodea]

Here's my version of a phase inverter with high voltage swing capabilities, built around my custom made IT26 xfmr and cathode choke. The amplification is by default (like in any LTP/Schmitt inverter) a bit less than mu/2. Try to obtain THD levels like this with classic inverters!
A direct application of this can by the input/driver stage in a PP amp, with or without GNFB - in my opinion eliminates at least one stage

 

[Dorin Bodea]

... and this the response for 2Vrms input, about 30Vrms output between phases, for 6N6P/ECC99 with 16mA per branch