Stereo phono amplifier circuit with bass control composed of LM1877

As shown in the figure, this is a stereo phono amplifier circuit with bass control composed of LM1877. The stereo metal ceramic pickup picks up the stereo left and right channel audio signals on the turntable, which are input through two 1MΩ potentiometers and coupled by two 0.1μF capacitors to the input terminals 6 and 9 of LM1877 respectively. After amplification, they are output from pins 2 and 13 respectively and sent to the left and right channel speakers respectively. Among them, the two 1MΩ potentiometers are volume potentiometers, and the two potentiometers are linked to adjust the volume. The two 1MΩ resistors connected to pin 1 are used to set the DC bias operating point of the amplifier, and at the same time, they form an input high-pass filter with the 0.1μF coupling capacitor. The 100kΩ potentiometer connected to the feedback loop between pins 2 and 7 of the amplifier (similarly, the 100kΩ potentiometer connected to the feedback loop between pins 13 and 8 of the amplifier) ​​is a bass control potentiometer. The 2.7Ω resistors and 0.1μF capacitors connected in parallel with the left and right channel speakers are used to filter out high-frequency noise.