The output transistors MJL21194 are of great power and performance. They must be very well adjusted with through screws, washers and nuts and properly insulated from the heatsink with mica insulators. Remember to use silicone grease and tighten the... Electronics Projects, Stereo Amplifier Of 500 Watts Quasi Complementary "audio amplifier circuits, transistor amplifier, " Date 2019/08/04