The VBE multiplier is the circuit around the 2N3904 transistor in the schematic I posted in reply #7. For simplicity, replace the 68 Ohm resistor with a short. The circuit multiplys the Base to Emitter Voltage of the transistor so that it acts like several diodes in series. The pot adjusts the amount of multiplication so that the power transistors turn on just enough to eliminate crossover distortion. As the power transistors heat up, they need less Voltage to conduct the same current and the VBE multiplier (hopefully) reduces the Voltage applied to the Bases.
A power transistor could be used to make it easier to mount to the heat sink. You will need an insulator. This circuit works better with a high beta transistor, the beta interacts with the resistor values to some extent. It takes a little experimentation to get the thermal compensation just right. But this is a guitar amplifier, it doesn't need to be perfect.
A power transistor could be used to make it easier to mount to the heat sink. You will need an insulator. This circuit works better with a high beta transistor, the beta interacts with the resistor values to some extent. It takes a little experimentation to get the thermal compensation just right. But this is a guitar amplifier, it doesn't need to be perfect.