I am a bit confused by the terminology. When I was involved with tube power amps there were three schemes which went like this.
"self biased" ....Bias voltage derived by a fixed resistor from the plate voltage. No provision for any adjustment. Output power reduced by about 10 percent compared with adjustable.
"adjustable bias"....Bias provided by a separate voltage generated by the power supply, and having adjustment capability by a pot.
"AutoBias"....Same as adjustable except with the pot replaced by a circuit that makes measurements and adjusts voltage accordingly.
"self biased" ....Bias voltage derived by a fixed resistor from the plate voltage. No provision for any adjustment. Output power reduced by about 10 percent compared with adjustable.
"adjustable bias"....Bias provided by a separate voltage generated by the power supply, and having adjustment capability by a pot.
"AutoBias"....Same as adjustable except with the pot replaced by a circuit that makes measurements and adjusts voltage accordingly.