RF Osc for Audio Output Bias.

[Eddystonepete]

Seems like an awkward way to avoid dissipation in a cathode resistor. They could have gone the whole hog and used a cap dropper for the heaters too. That said the live chassis aspect means that it limits the amps usefulness. Further thought, why not tap off the heater chain with a diode to give the neg. bias ? That could be used with a cap. dropper.

Peter