Stereo Balance indicator with control function circuit diagram

Using electronic diagram below can be designed a simple balance indicator with control function. If it is connected to the amplifier circuit equipped with two potentiometers for balance, you will have, in fact, balance control, and at the level. For this circuit to work properly it is necessary that the two potentiometers used to be double.
IC1's circuit forms a differential amplifier and resistors R5 and R6 creates a virtual ground for LED output as needed to obtain a positive or negative voltage, although power is asymmetric.