has driving 90lb’s from a 921a ever been tried?
I guess it cannot be done ..but maybe perhaps with modification?
if not, could the 901a be modified to make it more stable around Q6 (say with a transister IC ..3046?) and omitting the diode clusters..
I am more focused on more exact scaling and tracking rather than temperature drift. (Does temperature drift effect scaling or just general tuning drift?)
the 921a’s are simpler circuits compared to the 901a’s