Thursday, October 6, 2016

Public Address system

The Public Address system shall be a complete system for amplifying sound signal from
microphones, background music source and distribute them to loud speakers at various
locations with provision to distribute sound on selective and zonal basis as shown on the
riser diagram.
-          Microphones ( wire & wireless )
·         Types:
-          Dynamic microphones
-          Condenser microphones
-          Ribbon microphones

·         Specification
-          Sensitivity
-          impedance

-          Speakers
·         3 types ( wall mounted, surface mounted & recessed mounted )
·         Cover area approximately about 30 meter square and located every 6 meter at corridor.

-          Amplifiers
-          is an active component that increases the output signal of a sound source (e.g. microphone) and passes its output signal to a sound transducer (e.g. loudspeaker).
-          Capacities
( 120w, 240w............)

-          Matrix
§  The main unit for the system which work as the interface between the system inputs as ( microphone, radio & CD player ) and the ouput units as speakers
-          FM\AM radio

-          CD\DVD Player

-          Volume control ( attenuator )
·         Located at closed rooms and it have different wattage capacities depend on number of speaker connected to volume control.

-          Network audio adaptor
·         Used only in IP public address

-          Rack
·         All previous devices will be located inside the rack which will be located in the main control room of the project

-          Types of cable used in public address system
·         Shielded twisted pair cable 2 x 1.5 mm   

-          Types of conduits  used in public address system
·         PVC Conduits
·         EMT Conduits used in Exposed installation when using public address in voice evacuation
·         UPVC Conduits used in outdoor installation

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