Many low pass filter circuits for subwoofer are given here and this can be simply another one. The circuit given here using the opamp TL062 from ST Micro electronics. TL062 is twin high input impedance J-FET opamp that has very low power consumption and high slew rate. The opamp has wonderful audio characteristics and is extremely appropriate for this circuit.
Out of the 2 opamps within TLC062, 1st one is wired because the mixer cum pre amplifier stage. The left and right channel are connected to the inverting input of IC1a for mixing. The gain of 1st stage will be adjusted using POT R3.The output of the first stage is connected to the input of second stage through the filter network comprising of parts R5,R6,R7,R8,C4 and C5. The second opamp (IC1b) is a buffer and also the filtered output is offered at the pin 7 of the TLC062.
