40W power amplifier circuit

It is a 40W two-channel power amplifier using NE5532 as preamplifier and equipped with treble and bass controls.
    NE5532 is a well-known high-speed, low-noise dual operational amplifier. In this circuit, the left and right channels each use their own One
and a half o This stage voltage gain Av = 2010g (R3佃5)≈24dBoC7～ClZ and island～R12 and RP3褂)4 are composed of
attenuated high and bass control circuits. Although the attenuation of this control circuit is larger, it can achieve a wider control range
.
    The power supply of the circuit adopts double-bridge rectification and large capacitor filtering. The power amplifier IC is directly
powered by the rectified and filtered ±27.5V ; the pre-stage
is formed by the ±27.5V power supply, which is stabilized by the three-terminal integrated positive and negative voltage stabilizing blocks 78 1 8 and 7918, and filtered by the island ~ ±18V power supply. This power supply method has a simple circuit structure and stable operation.
    After the input signal is input from the input terminal, it is appropriately attenuated by the potentiometer RPi, and then coupled to the input terminal 3 of Icl via C1. After being amplified by IC1, it outputs a full RC tone control circuit. The RC circuit performs necessary
adjustments on different frequency components in the signal spectrum.
After boosting and attenuation, R13 and the island are coupled to the final power amplifier IC2 for power amplification.