There are three modes of operation:
1. Press-to-talk, release-to-listen using the speaker as the microphone in the talk mode,
2. Full duplex, simultaneous talk/listen when a close-talking, noise-canceling gooseneck is plugged in.
3. As a headset station when a headset is connected instead of a gooseneck mic.
The full duplex feature will work in moderately noisy environments because of the deep cut in sidetone automatically applied when the LS3 senses that a microphone has been connected but not an ear speaker. In this mode, sidetone can be adjusted with a front panel recessed screwdriver adjust control which is rotated until any feedback is suppressed. When the LS3 senses a headset, sidetone is automatically restored to a setting which is fixed, but ideal for use with a headset.
Since LS3s are likely to be used in remote locations, they are subject to having their front panel controls left in positions that will prevent communications from the Master Station. The level can be turned down, the speaker switch left in the Off position etc. Pro Intercom Master Stations are all equipped with an override tone generator. When this inaudible tone is sent out and received by an LS3, it automatically shifts to a predetermined group of settings, restoring volume, and resetting the speaker setting to Listen. The choices of these override settings are determined by the positioning of links on the rear of the LS3’s circuit board, and fully explained in the instructions. When override is controlling the LS3, a green LED lights on the front panel.
The LS3 version is mounted on a thick, sturdy aluminum plate for flush mounting and fits a U.S. 6-gang electrical box. Circuit connections are via a plug-in terminal strip on the rear. The mating plug is provided.
The multi-circuit model of the LS3 is designated the LS3M.
The LS3T version is fitted into a heavy metal enclosure with keyhole slots on the back and plastic feet for desktop use. Circuit connections are via XLR connectors on the top/back.
The multi-circuit version of the LS3T is designated the LS3MT.