This edited schematic diagram is came from the Service manual of CARVER 705X, an audio power amplifier produce at 90-s era that using OCL type amplifier 300 watts output.
CARVER are a audio vendor that came with advance components and different architecture of the schematic diagram.
Looking for genuine service manuals check HERE.
Here is edited schematic diagram of CARVER 705X it can be reach up to 300 Watts over 4 Ohm load.
By looking at the schematic above, we can ensure that the power amplifier circuit is symmetrical.
The first block is the OPAMP which functions as a buffer amplifier.
Next block is a differential amplifier using transistor 2SC2240 2SA970.
GAIN factor can be determine by calculation between R46,R48 as paralelled feedback resistor with R21 as input resistor.
Q4 and Q7 are Voltage amplifier to amplify signal came from the preamp transistor Q2, Q5.
There is a servo driver feature using a transistor Q9 laying between collector of Voltage amplifier.
The amplifier using 2 stage Driver Amplifier as using Q12, Q14 pair with Q13 Q15 as current Amplifier.
Final Power amplifier using 2 pair of 2SC3281 / 2SA1302 that can deliver 150 Wats of dissipation each.
It mean the maximum dissipation of the Final Power is 300 Watts at 4 Ohm load.
OCL POWER 300 WATTS
SKEMA YOHAN ( HERE )