The AC-1h provides an active, balanced, audio output and a bridging, balanced, audio input that is ideal for IFB feeds from intercom systems and any other system that needs a bridging feed. Depluggable screw terminals give you easy access to the local audio input and outputs. An active audio limiter gently prevents telephone line overload while maintaining optimum "send" levels so callers will have no trouble picking up audio from your couplers. The AC-1h includes gain controls for both local send and receive levels. Designed from scratch in 2008, the AC-1h is microprocessor controlled and adds even more features beyond the original AC-1 coupler series.