A public address system (PA system) is an electronic sound amplification and distribution system with a microphone, amplifier and loudspeakers, used to allow a person to address a large public, for example for announcements of movements at large and noisy air and rail terminals.
The term is also used for systems which may additionally have a mixing console, and amplifiers and loudspeakers suitable for music as well as speech, used to reinforce a sound source, e.g., recorded music or a person giving a speech, and distributing the sound throughout a venue or building.
Simple PA systems are often used in small venues such as school auditoriums, churches, and small bars. PA systems with many speakers are widely used to make announcements in public, institutional and commercial buildings and locations. Intercom systems, installed in many buildings, have microphones in many rooms allowing the occupants to respond to announcements.
Sound reinforcement systems and PA systems may use some similar components, but with differing application, although the distinction between the two is not clear-cut. Sound reinforcement systems are for live music or performance, whereas PA systems are primarily for reproduction of speech. In Britain any PA system is sometimes colloquially referred to as a Tannoy, after the company of that name now owned by TC Electronic Group, which supplied a great many of the PA systems used in the past.
Choose an amplifier with the right amount of power. School auditoriums or churches need 100 to 300 watts, a nightclub 1000 to 2000 watts, an outdoor concert 10,000 or more watts.
Select speakers that handle exactly the wattage of the amplifier. Overloading and under loading speakers can damage them.
Get a mixer if you have many microphones, CD players, turntables and other devices. Include an equalizer if you are working with live music or complex sounds.
Allow speakers, singers and actors to move freely by choosing wireless microphones. Look for sound quality, durable hardware and multiple frequencies.
Choose cables with tough, flexible casing that are long enough to meet your needs, but not so long that you lose too much signal. Shielded cables prevent noise from nearby radios and power tools.
Your public address system can be the difference between a successful event and a disaster. Whether you need a portable or a built-in system, consider every component so you get the power and features you need without wasting money on capabilities you don't need.
Tips & Warnings
Rent a system before purchasing to learn what you truly need and don't need. Spend time talking with the technicians at the rental service to learn more.
Test every piece of the system before you buy a used system. Disconnect and reconnect everything yourself as part of the test.
Protect your equipment with strong, weatherproof and padded cases. Always pack and cover equipment against dust and moisture when not in use.