Here’s a simple circuit you can use to boost more bass from your music. It can be powered by 9V battery or a 12V DC adapter. Take note that this is just basically a 1 band tone control with +- 17dB range at 60Hz bass frequency. You need it to connect before the amplifier input. This can’t be connected directly to speaker. The output of this circuit will be connected to the input of your amplifier and the input of this circuit will be connected to your audio source(i.e. mp3 player).
For deeper bass, you can try to increase value of C2.
Simulation Result
The frequency response at different setting of the potentiometer (0% – 100% at 10% increment)
