The Henry Engineering MixMinus Plus is a differential amplifier designed for use with telephone hybrids in broadcast applications. The MixMinus Plus eliminates the caller audio from an entire program, the program-minus-caller audio is fed back to the caller via the telephone hybrid. Up to 40dB of caller null is typical. There are inputs for both caller and program signal sources via screw terminal connections. The MixMinus Plus needs no adjustment once installed, and will work with virtually any console and hybrid.