The series ofserves to eliminate in system that comes from the power grid. Noise coming from power lines is often called the HUM is located at 50-60Hz frequency range. The series of audio serves to eliminate at 50-60Hz frequency range is. Audio is made with an active filter of the IC TL071 which serves to throw the 50-60Hz frequency.
Audio Noise Reduction Circuit
Audio noise reductionis equipped with 2 units of VR that serves to regulate the frequency cut-off point of the noise and the noise level in the exhaust. VR1 serves to set the cutoff frequency noise and VR2 serves to regulate the level of noise is discarded.