Installation and debugging of Powon-HE328 Hi-Fi power amplifier

Powon-HE328 50w×2 Class A ground push-pull power amplifier
is improved by referring to the ground push-pull principle of the American Harman/Kardon PS2200 power amplifier.
    The circuit principle is shown in Figure 7-37. In the figure, VT1 and VT2 are balanced complementary differential amplifiers. VT3 and VT4 are
cascade (source and base) circuits designed to overcome the voltage characteristics of VTl~-VT2 field effect transistors, so that the first stage has good frequency characteristics.
sex. VT7~VT10 are Miller constant current power supply circuits of differential circuits, which make the common mode suppression bit of this stage high. VT11 and VT14
form a pair-to-ground push-pull circuit (Wallman circuit). This is an inter-stage voltage conversion circuit, which is effective against power supply noise. It has good
suppression effect on digital noise. Among them, VT11 and VT13 are current bootstrap tubes. The function of these two tubes is to overcome the influence of Cob on the circuit and can further
reduce the distortion rate by about 40dB. VT15. VT16 is the driver of current amplification. circuit, the final power amplifier is a parallel emitter output
circuit. The circuit uses a quasi-DC negative feedback circuit without large-loop negative feedback, thereby eliminating
the interference of the speaker's reverse electromotive force on the front stage. oVT23--VT28 is a "Kubota type" high-speed regulated power supply, VT29~VT33 and VT22 is
the midpoint delay protection circuit n