Power amplifier using LF356

It is a power amplifier using LF356 as preamplifier and equipped with DC servo circuit. In line with the principle of simplicity, the circuit
uses an I_F356 to form an attenuated tone control circuit with a pass-through switch . The function of the pass-through switch
is to cut off the tone circuit when playing music with high fidelity (such as CD records), so that the amplifier outputs unmodified
sound.
    For the power amplifier A1514A, remove the bootstrap circuit and connect pins 6 and 7. After canceling the bootstrapping, although the output power
is reduced by 4W, it is beneficial to reduce transient distortion and improve the sound quality.
    The power amplifier is DC. By short-circuiting the inverting auxiliary terminal in the typical application circuit and adding LF356 to form a DC servo
circuit, a DC power amplifier circuit is formed.
    The power amplifier stage uses a double-bridge rectifier power supply, and the pre-stage and servo circuit use independent active servo power supplies.