Using two common operationals, such as 741, this circuit serves as a medium control in an amplifier. The power supply must be symmetrical between 6 and 12 V. The circuit is placed between the signal source and the amplifier input. The signal cables must be shielded. C1 and C2 may have values between 22 nF and 100 nF as the desired control. Other operational equivalents may be used.
