Bass boost circuit for audio amp

          This schematic is of bass boost circuit which  can be made by popular and easily available ic 741.By adding few components a simple bass boost circuit can be made for your amp.The power supply required is dual power supply of +/- 12V.
           The switch S1 is used to bass boost or cut.When the switch is closed bass cuts(No bass).When switch is open Bass boost is on

Low pass filter for subwoofer

This is high quality low pass filter for subwoofer for best bass response to your audio system.It uses 4558 opamp ic for its operation.It has volume control,bass boost control and frequency control pot for best results.The power supply required is dual power supply of  +/-  12V.The pin no. 8 of IC 4558 is connected +12v and pin no. 4 of IC  4558 is connected to -12v of power supply.The switch SW201 in scematic is for changing the phase to achieve accurate bass in listening postion.It also has Hi level inputs facility to take source signal from another audio amp.