This is a novel OCL power amplifier circuit with bootstrap. The circuit principle is shown in the figure. It consists of NE5532 (other op amps can also be used) and two high-power NPN transistors. BG1/R4/R5/R6/R7 form the push stage, where R4/R7 determines the gain of the latter stage circuit. BG2/BG3/D1/D2/R8/R9/C7 form the output stage.
The characteristic of this circuit is that a certain voltage is applied to the output tube when it is static, so that it is in the class A bias state. Such a circuit has small distortion, high power, and high efficiency.
Debug: Adjust R6 in static state so that the collector voltage of BG3 can be 0.6V.
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