The Crow 300 Power Amplifier

In 1987 I decided to try my hand at designing and building a high-end amplifier capable of giving the Phase Linear a run for the money. The result is my Class AB, variable Widlar current mirror biasing MOSFET discrete output power stage Crow 300. This is a 150 watt R.M.S. continous power (@ 8 ohms) per channel prototype I built that winter. Using my knowledge of variable frequency AC inverters (industrial motor speed controls) as the basis, I wanted to create an amplifier that could, like an inverter, monitor the voltage and current demand of the load (speakers) and adjust the bias (the electrical current precisely supplied in this case to make the power transistors that actually drive the speakers work most efficiently) in a "constantly calibrating" fashion. The end result is a very clean signal output that can respond to heavy power transients almost instantaneously, yet avoid wasting power when low music levels are present.
Crow's Own Amp Design / Christopher S. Rider / syzygy@oldcrows.net