This circuit was adapted from a 1995 Electronics Now magazine. He shows how to implement a type of tone control Baxandall using an integrated circuit 741. The control for bass and treble uses a 9 V symmetric power supply. The power supply must have excellent filtering, but may be utilized in the own amplifier to which the circuit will work. If mounted on a separate board, input cables and output cables for signals must be shielded. Equivalent operational amplifiers can be used. The level of the output signal excites the inputs of most common audio amplifiers. For a stereo version must be used two units supplied from the same source and with a double operational can save space on a printed circuit board. The pots used to be linear type. The circuit does not include volume control.
