The circuit is based on an Integrated Circuit which provides three sharp active filters for each channel. Three independent controls vary the amount of light for low, midrange and high frequencies. In addition, a built-in microphone is incorporated which allows the circuit to capture the ambient sound and to operate without requiring a connection to your stereo system. The circuit can handle up to 200W of lights per channel. Power supply 12VDC 500mA. Positive center. Recommended model: RPR-12600-P5