This is a bass booster circuit that use transistors as base. It is designed to increase a low frequency of audio on cheaper than ICs or normally circuit.
t is Treble Booster circuit help give the sound of music that you listens to bright go up. it is cheap, easy to build because a few pats with IC-741.
The Passive tone control circuit, to adjust bass-treble with no the expansion, use equipment R and C only, to filter frequency,easy without power supply! [...]