Amplifier circuit built-up is pretty nice not always complex. There are a series of amplifiers that I saw a picture of the kit immediately. The circuit is quite simple, there was the most complex in the pre-amp and its protector. Click to view larger | CSE-Circuit Schematic Electronics How a series of ...Op-amp stage 1 is the heart of the circuit, the input stage with enough power to drive the power transistor. Sensor1 ntc & 2 can be attached to the main heatsink, this is optional so it can be eliminated, its functions to lower the bias voltage value if the heatsink overheating. There is no bias trimpot, R6 and R8 instead divide the voltage so we get <= 0.6V at the base driver tr. If the voltage is just a little more driver transistors can be damaged and could trigger the final transistor is damaged in congregation / pairs. These transistors are used frequently broken, but after replaced by Sanken, safe. Thus the risk of the snaps without a limiter amplifier. A pair of Q1 & ...