The TC-Z904B/Z906B/Z908/Z912 infrared transmitter is a microprocessor based central unit which is designed to modulate and transmit 4 or 6 sound channels to different carrier frequencies. It features independent channel volume control, independent channel output level indicators, and independent channel audio output for sound recording. Test mode produces a different frequency tone for each input/channel. Two BNC sockets can link up infrared radiators in two lines. Multiple interpreter consoles can be connected to the transmitter in a daisy chain.