The MCS-D 3173 H chairman microphone unit provides a microphone, priority and clear button, five voting buttons, four navigator buttons for channel selection and volume control of a connected headphone as well as a two-way loudspeaker system. The LC display displays the selected channel, headphone volume, device ID or messages. The microphone button is used for normal switching on and off of the microphone. The chairman does not depend upon the maximum number of open microphones. With the priority button, the chairman can join the discussion and mute the activated delegate microphone units. The clear button switches off all of the activated delegate microphone units. The illuminated LED on the microphone button and the LED strips on both sides indicate that the microphone is ready to speak into. The integrated loudspeaker provides superb clarity and intelligibility. If the participant switches on his/her microphone, his/her own loudspeaker is switched off. The Revoluto microphone array technology with integrated microphone capsules provides a so-called corridor characteristic which ensures a wide range of good voice quality. The speaker can move freely, i.e. can stand up or sit down, can move his/her head and move towards or away from the microphone unit. Power is supplied to the microphone unit via the bus cable. As part of the MCS-D 200 conference system, the microphone system can be employed at any position in the bus network.