Public Address System was design for public announcement in public building, schools and commercial building. Should there be any fire breakout or emergency evacuation process the announcement coming from the speaker has to be easily understood. A good public address system design will ensure that people will be able to hear the announcement clearly and not confuse with what it is trying to say. You can also play back music in with this system.
The speakers will consist of ceiling speaker and box type distributed evenly to the area. Office areas or restaurant will require this type of speaker. In places like car park or outdoor area the speaker use will be horn type as this will produce louder and long throw.
To design the public address system design in the building we need to determine the number of ceiling speakers needed to cover the area. Most of the buildings will either have high level ceiling like the lobby area at the entrance or lower level ceiling commonly seen in the office block. By indicating the correct number of the speakers needed for each this area will ensure coverage. As a rule of thumb the more ceiling speaker the better is the sound distribution. From here we can easily calculate the number of amplifier needed to power the speaker. Finally we divide the speakers into different zones for easy identification like different zone for each office block in each floor and zone for lobby area and another zone for car park area.
The ceiling speaker is usually a low wattage type and with built-in matching transformer it can be link together with other ceiling speaker. With this you can link to as many ceiling speakers as possible into one zone but the total linked speakers’ wattage must not to exceed the power amplifier wattage. So let say your power amplifier is a 240 wattage amplifier and you can link up to 80 numbers of 3 watts ceiling speakers.
If you want to design sound system for meeting room then you will need a bigger loudspeaker and powerful amplifier as compare to public address system. Meeting room and auditorium will require this system for live speeches and audio playback.
One of the advantages using bigger speaker is that it can produce louder sound level that will definitely produce better sound clarity. Same with the public address system design we need to ensure that sound coverage is even and loudness is maintained throughout the room. In order to achieve these design criteria, the speaker has to be aligned and position in such a way that the sound will be projected to the listen audience. Sometime we need to include long throw speaker to cover the back rows seats and the short throw speaker will be align to the front rows.
Thus designing a sound system for meeting room is much more complex compare to design public address system. A small meeting room design will be simple because it will only require two loudspeaker producing but for a large room like the auditorium the design will need about 8 to 12 of such speaker quantity in order to produce a good sound pressure level to all the seating area.