Excellent performance two-channel subwoofer circuit

Circuit principle: The input signal is processed by a fourth-order low-pass filter composed of IC1-1 and peripheral components with a changing slope of 24db/oct (the value in the figure is fc=70Hz, A=8.2dB), and then is processed by IC2 The inverting AC amplifier centered at -1 performs 10 times buffer amplification and outputs it. The greatly enhanced low-frequency signal and the original signal are sent to IC2-3 by C4 and C3 respectively for mixing processing, and the mixed signal is output by C5. W controls the mixing amount of the low-frequency signal and the original signal. In order to ensure that the C5 output signal is 'original' when W is turned off, the gain of this stage is set to 0 dB. Component selection: The error of R and C, which determine the low-pass cutoff frequency, should be less than 1%. R2--R5 can be selected from resistors with an error of 5%, all of which use 1/8W RJ series; the non-polar capacitors use CL series, C4, C4 , C5 uses tantalum electrolysis; it is best to use a digital meter to select and test RC components, and use authentic TL084 for IC. When in use, just connect this circuit in series between the signal source and the power amplifier.