Added a second potmeter to control filter resonance of the bassline. Had to place it horizontally to avoid obstructing the usb cable.

new situation :

pot1 : bass line filter cutoff control
pot2 : bass line filter resonance control 

This allows to shape your sound like an analog synth. But there's more ! You can not only filter synth like sounds such as the square and sawtooth synth leads.  You can apply to piano, flute, gunshot, applause, oooh choir, bird tweet, telephone ring, ... 

Amazing effects :-). The code is updated in the repo.

 See photo for the new setup :