Thanks for the help. I have attached the service manual and schematic I have obtained.

In of itself, "325mV" is a meaningless term.

I agree. I should have been a little more specific. The emitter resistor value is 1 ohm, rail voltage is 77, and number of transistors is 36.

325mV is part of an equation that will get you to your answer. Also I'd stay away from any bias procedure where the temperature at some location is the target. The temperature at any particular location will be a function of dissipation and ambient temperature and airflow.

To calculate what each transistor is dissipating, you can sample the idle current through it by measuring the voltage across each transistors emitter resistor, then dividing that voltage by the emitter resistor's value. That will get you the current. To find the power, while idling, of each transistor, multiply each transistor's current by the voltage across the Emitter and Collector.

325(mV)/0.15(Ohms)= 2.1(A), 325(mV)/0.47(Ohms)=691(mA)

If the rails are low-ish, 2.1(A)*40(Volts) = 86(Watts) per device, 691(mA)*40(Volts) = 27(Watts) per device.. If this amp does not have forced cooling, given time, it will exceed 120 deg (F), I believe. I'd check the bias values. Make sure all of the emitter resistors are not open and all have a similar voltage drop across them.

Based on the stated bias (325mV), rail voltage (77V)emitter resistor value (1 ohm), and number of output traunsistors (36), I get this equation:

325(mV)/1(Ohms)= 325(mA)

325(mA)*77(Volts) = ~25(Watts) per device

25(Watts)*36(Devices) = ~900(Watts) consumption at idle

Based on my minimal understanding of class A being extremely inefficient the 200WPC is a little high for the 900(Watts) dissipation.

If I use the equation from the review by Atkinson (stereotimes) in regards to calculating true class A watts I get this:

If assuming 200 WPC:

Using equation: sqrt(WPC/2*speaker Ohm)

sqrt(200/2*8) = 3.54A

then using: Amperege/transistor pairs per channel

3.54/9 = 393mA

393mA = 393mV given 1(Ohm) resistor value

Based on that the voltage change across the resistor should be higher than the spec. Of course I am assuming the equation is an accurate estimate.

If it is and I reverse the equation given the 325mV bias I would get only ~137 WPC in class A.

I have left the unit on for several hours and I think the highest it has gone is around 130F. Ultimately I plan on setting the bias (not by temp

) and checking various components. I just find this stuff very interesting and enjoy learning about how these amps work.