AV Australia has a variety of packages of compatible components well suited to specific uses, venues and budgets.
A PA, (Public Address) system, has three components:
An input device, (such as a microphone), converts sound waves into electronic signals.
An amplifier then boosts that input weak signal produced to a level that can power a speaker
Loudspeaker/s then convert electrical impulses from the amplifier back into sound waves
There are numerous different types of PA systems but, with some initial due diligence, your selected PA will fit for their needs and facilitate broadcasting your message for many years.