Clear-Com’s TW-12C intercom system interface is designed to provide an electrically isolated interface between two intercom systems, without compromising the audio quality of either system. This transparent device consists of two identical 2-wire-to-4-wire hybrid networks, with transformer isolation between them. This complete electrical isolation breaks ground loops that occur when two systems are run from separate power sources - thus elimnating hums and buzzes. The TW-12C compensates not only for level differences between systems, but for varying impedances caused by transformers and capacitance on the lines.