The basic task of the sound system of facilities and institutions is to alert the persons and indicate the problem in case of danger (fire or any emergency), and to report the evacuation route, while in the case of normal activities inside and around the facilities the system can be used to play music content, broadcast advertising messages, and issue various announcements or notices.

Most often they consist of an appropriate number of speakers, a volume controller with or without so-called. overwrite functions in the event of an emergency and an amplifier.

 Due to the large line lengths, there are transformers at the outputs of the amplifier, which raise the voltage of the speaker power line to 100V, while on the speaker side there are so called. stepdown transformers that move the specified voltage to the required level.

Apart from this, the components of the equipment are audio sources (MP3, FM and CD players, microphones, various speech modules or automata, intermediary modules eg from telephone exchanges, etc.), as well as devices for integration with other technical systems (alarm, PPZ , access or CCTV).

Due to their ability, public address systems have quickly found their use value in all types of business premises, large retail outlets,
office buildings, health facilities, airports, rail and buses
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