PRS100 is a talkback desk with 4 wires. It allows:

• To receive orders on a loudspeaker or headphone (pluging headphone, cut off the loudspeaker). Amplifier and loudspeaker  are  enough powerfull to allow a perfect intelligibility. It is also possible to use an external loudspeaker. Transformer balanced input on XLR. A warning shows incomming order by audio detection.
• To send orders from the microphone (front panel XLR with phantom supply) to a transformer balanced output on XLR. The microphone level is adjustable (peak led) and a limter avoids any input saturation. An adjustable dimmer reduces the loudspeaker output,during the sending order. A switch at the rear copy input to output allowing to chain several PRS100.
• Unit can be powered from the mains or a 12V battery.

Some other talk back desks are available, referenced PRS200, PRC100.