Designed to replace the STK-0050 in the Pioneer SX-780 and other stereo receivers using the old Sanyo module. They have been successfully used in Fisher, Technics amp and receivers. Eliminates the probability of poor quality modules. Discrete design allows for easy repair. Improves reliability and performance. Can be used with many amplifier front-ends to make a complete amp. You need special tools such as a soldering iron, DC voltmeter, side cutters, needle nose pliers, screw drivers etc. Prior Audio Electronic knowledge and interpretation. There is help at Audiokarma. All Electronic Components are supplied. Listing is for two blank PCB’s, heatsinks, all parts, wire, documents, assembly instructions for two modules. Heatsink is tapped for M3 x 0.5 screws, supplied. The module will improve the amplifier’s reliability and operational specifications for stereo’s using STK modules, up to 85 watts. Outputs transistors are specified as Onsemi 200W devices. There is another listing/item available, using the lower power 150W Toshiba devices, which is offered at a reduced price. Output transistor bias adjustment is included in circuit design. This allows for the modules to be adjustable for matched performance. 0.02% (20-20KHz, 4-8 ohm, 31mA bias). Gain (based on Pioneer SX-780 design) = 15.5 (23.8 dB). Bias: Each emitter resistor in the SX-780 are 0.22ohm, that would be 0.22 0.031A =. Across each emitter R or. Across the two of them. Increasing the bias current will make the output transistors to run hotter. This lowers the crossover distortion and allows for a larger class “A” operating region. Audiokarma web site for additional details on our design.