There are a number of electronic parts and circumstances to consider when choosing the best PA amplifier system for your needs. Budget, music style, and types of instruments in the band will be important to identify when choosing a PA. You should take transportation capabilities into consideration as some PA amplifier systems can grow quite large and extensive. There are three basic components to building a working PA system: power amplifiers, mixing board, main speakers, and monitors.
If the artist or band is a quieter acoustic act or just looking for a practice PA system, combo PAs are a great option. These are known as powered mixers and have around eight inputs on the basic models; they are compact with mixing consoles and power amps built into the units. The user can get small PA speakers at 200 watts each or less to combine with the powered mixer. These models start around $300 US Dollars (USD) and can provide great sound for small acts. The, you'll need speakers and a monitor to complete the PA amplifier system.
Beyond smaller performances, you may need to assemble a larger, more traditional PA amplifier system. Power amplifiers power the main speakers and the monitors. The speakers and monitors are almost always unpowered on their own, so you should run one amplifier to the mains and another to the monitors. Sometimes, the monitors or speakers will be self-powered, which won't require a power amplifier but will still be plugged into the mixing console.
Most mixing boards are unpowered but run as the main console among the amplifiers, compressors, main speakers, and monitors. You can buy basic accessories such as cords separately if they are not included in the PA amplifier system package. Standard mixers will have 8 to 12 channels, which should be sufficient for most groups. These mixers start at around $300 USD. If the band exceeds six members and runs several microphones, it will need a larger mixing console, which can run up to $800 for a basic, good model.
Twelve- and 15-inch (31- and 38-cm) speakers are standard sized and are usually sufficient for small rooms, small bars, and clubs. Fifteen inchers (38 cm) are the best way to go for most acts. Two main speakers and two or three monitors will suffice for most bands. If the band is looking to add a subwoofer to the mix, it will need to purchase another amplifier to power it. The low end of live performance subwoofers runs at around $200 USD.
You can purchase PA amplifier systems new as a package deal from major retail outlets. Shopping used is also a great way to build your PA amplifier system piece by piece, customized to your liking. A rack case will help keep all the power amplifiers in one box. This is highly recommended to protect and transport the gear. Speakers stands and cords are added accessory costs that you should account for as well.