SSS phase inverter

[txbluesboy]

I understand that the Steel String Singer used an Ampeg SVT style output section ( Isodyne?). This has a driver section after the phase inverter feeding into what looks to be a cathode follower with an adustable voltage divider circuit. Is this actually a cathode follower or some sort of constant voltage bias regulator or what? Who is up to trying to explain this system to a clueless boy from Texas?