Using active circuit for tone control means that we can provide cut and boost, maintaining overall amplifying factor of original system (before adding the tone control). Very simple circuit can be built using Baxandall configuration, which uses only capacitors, resistors, and one transistor. The firs potentiometer give treble cut and boost. Note that the potentiometer is connected to the amplifier input (transistor base) via the center tap. When we turn or slide the potentiometer tap approach the input line, then the input signal which is high-passed via capacitor will be amplified. On the opposite, when we turn or slide the tap toward the feedback line then this filtered signal is cut or attenuated. The second potentiometer is similar, but it works for bass signal because the capacitor filter is configured in different formation.