The public address system is a branch of the sound reinforcement system and the sound reinforcement system, also known as the professional sound system It involves three disciplines:electroacoustics,sound construction and music. Therefore, the final effect of the public address system involves a reasonable and correct electro-acoustic system design and debugging, a good sound propagation environment (building sound conditions) and accurate on-site tuning and all those three factors are indispensable. The public address system is mainly composed of signal sources, power amplifier equipment, monitoring equipment, control equipment, fire accident broadcast control equipment, user equipment and broadcast transmission lines.
The design of the best public address system is firstly the transmission method, and the output power feeding method of the system adopts the cable broadcasting transmission method. For line attenuation requirements, in the public address system, the line attenuation from the output of the power amplifier equipment to the farthest user speaker on the line should meet specific requirements; the feeder line with constant voltage output should be used, and the output voltage should be 70V or 100V.
Also we should pay attention to the calculation method of the capacity of the PA (power amplifier) in the design of the public address system, the calculation method of the fire accident public address system, the backup of the power amplifier and the power amplifier in the public address system should be equipped with a backup power amplifier so that if something wrong happens, it can be started automatically or manually. The power amplifier used for important broadcasting (such as the power amplifier of fire accident broadcasting) and its backup power amplifier should be able to be put into use automatically when the working power amplifier fails. The number of spare power amplifiers should be determined according to the capacity of important broadcast loads.