Integrated OTL power amplifier circuit composed of TDA2040

The OTL power amplifier circuit composed of the integrated power amplifier TDA2040 is shown in the figure. It uses a +32 V single power supply as the operating
voltage. The voltage gain of this circuit is 30 dB (amplification 32 times). When the speaker impedance ZBL = 4 Q, the output power is I5W.
When the speaker impedance ZBL: = 80, the output power is 7.5W.
    In this circuit, the signal voltage is input from the non-inverting input terminal of the integrated power amplifier integrated circuit. cl is the input coupling capacitor. RJ and
R2 are bias resistors , which bias the non-inverting input terminal of the integrated circuit
the input impedance from being reduced due to the bias resistors R, Rz. Rs is the feedback resistor , which together with C4 and R4 forms an AC negative feedback network to determine the voltage of the circuit.
Voltage gain, the amplification factor of the circuit A=RS/R4. C7 is the coupling capacitor. R6 and C6 form the output end vibration elimination network to prevent the circuit from self-excitation. C, and
c5 are power supply filter capacitors.