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