It's the heart of an especial installation for the sound reinforcement in small town, high industrial plant for public announcement, emergency announcement etc. When the area to be conveniently covered is too large far a normal P.A. sound reinforcement installation an installation based an the  TR40401 allows transmitting audio signals up to 10km through dedicated telephone lines to amplifiers fitted with the receiving board RT40402.

• Microphone input for dynamic or condenser microphone (with PP)
• Auxiliary input (stereo-mono)
• Input/output for tape recorder
• Low and high tone controls
• Master level control
• Six output amplifiers with output transformer
• Signal generator for remote control of the receivers.

It is a power amplifier with a receiver board built in. When a signal from the telephone line arrive, the amplifier is turned on and the audio signal is connected to its input. At the end of the message the amplifier is turned off automatically and the system returns in stand-by status waiting for a new message.

• The device provides the following features:
• An input translator to connect the apparatus to the telephone line.
• A receiver for the signal that controls the ON-OFF status of the power unit P.U.
• An amplifier to increase the received audio signal to the level for driving the P.U.
• A -TEST- push button on the front panel for control the efficiency of the power unit during the installation and maintenance operations.
• Output power 75W or 120W.
• Outputs 4-8-16W and 70/100V with output transformer.