Public address (PA) system is everywhere. But it’s a setup that the audience only cares about when the sound quality is awful, like those screeches from the microphone or voices muffled. As part of the audio-team sound check or doing your thing on stage, it means that every speech, music, or sound is heard loud and clear.
Regardless of the design, configuration, or venue, perhaps, any PA system is incomplete without these devices.
This device is the hub that combines sounds from various sources that go out to the speakers and amplifiers. It holds inputs and outputs whose number depends on the audio signals that need to be supported (e.g., microphones and instruments).
For example, a 32 × 8 means 32 channel inputs and eight output channels. Recording studios often use 72-channel soundboards. The input strip of mixers typically has equalization, microphone preamplification, dynamic processing, routing, and level-control faders for functions.
The core of the PA system goes by a lot of names, such as mixing console, mixing board, audio mixer, mixing desk, and soundboard. Nowadays, you can select an analog mixer for the familiar physical layout, where each input at the back goes to its assigned place, or a digital mixing board, which provides flexibility for assigning input channels.
Some mixers also have built-in reverberation, or reverb, which occurs when a signal or sound is reflected and absorbed by surfaces or objects. In some applications, reverb can make speech less intelligible, but it can enrich music or voice as far as DJs are concerned.
Simply put, they carry the sound that everyone hears in the event. A PA system can have main speakers, subwoofers, and monitors. Because these speakers need to fill the place with sound, power is essential. This power is then magnified by a matching amplifier (amp).
- Powered speakers have built-in amps and do away with the nitty-gritty of audio setup. These speakers are found in cafes or midsize venues for live concert gigs, DJ performances, and in-home settings like cinemas and computer speakers. You will plug these speakers directly to an electrical source.
- Unpowered speakers derive their juice from the amplifier and appeal to people who want more control over the sound.
While powered and unpowered speakers are referred to as active and passive, respectively, some contend that the latter designation has more to do with crossover or how a signal is distributed and not whether the speakers have an amp or not.
Subwoofers bring in the bass and enhance the overall sound quality. They make a great addition to the PA speakers and even home-entertainment systems. Other options are stage monitors that let performers hear their sound. These speakers usually face or angled toward the band on stage.
Notably, public address speakers can vary from that sound-reinforcement PA system in line with volume levels and purposes.
Amplifiers are independent devices or built into speakers, noted above. Given how closely intertwined these two devices are, it’s only natural for you to consider during your purchase whether the amp has speakers and vice versa.
There are three types of amps: voltage, power, and current. Power amplifiers are used alongside PA systems and the subject of this section. These amps are also designated by a class that affects the distortion levels (linearity) and use of power (efficiency). You can refer to the graph on this page for details on amp classes.
The implication of these terms and others you will across about amps is that the devices ought to deliver (1) a level of loudness that matches the venue and (2) power to the speakers without burning out or distorting the sound.
These staples in the PA system come in various types, depending on the use. There’s a mic for church-based sound system, onstage performance, recording or mixing, and public announcements.
Generally speaking, microphones fall under two categories:
- Dynamic mics. The size of their diaphragms indicates the smoothness and depth of sound. They are almost all-purpose and less expensive than their priciest condenser counterparts. They are also more durable, with parts that can survive wear and tear.
- Condenser Mics. Their strongest suits are sensitivity and accuracy of the sound quality. The electronics that go into the diaphragms make them more labor-intensive and costly in the process.
Finding the right mic means looking into the inner workings of the device.
These wires and connectors allow the interaction of the electronics that make the PA system. Before you trip on any wiring or plug the jack to the wrong output, get to know them quickly:
- XLR connectors have male and female versions.
- TRS phone connectors, or phone connectors, are classified as stereo/balanced and monaural/unbalanced.
- RCA pin connectors are white and red cables that are often used in audio-video applications.
- USB connectors are for computers and other devices to connect to mixers.
- Speakon connectors have a lock that is turned clockwise when you plug them.
Cable connectors can transmit balanced and unbalanced signals. The first type is good at eliminating noise, while the second type is susceptible to noise interference.
Speakers can have XLR, TRS, or Speakon connectors, which figure commonly in power amps and passive speakers. For microphones, they usually have XLR or TRS jacks. Mixing consoles have input or output for devices with XLR and TRS connectors.
A PA System That Works for You
There are many ways to put together complete PA systems for weddings, parties, religious and corporate events, music festivals, and the like. For example, a basic DJ setup involves a controller, amplifier, and speakers. A mobile DJ can add to the above system with sound sources like microphone and DVD player to the mixer.
As events happen outdoors or anywhere outside four walls, portable PA solutions are gaining ground. The equipment is easy to transport from venue to venue. More importantly, some of these compact and complete systems come with rechargeable batteries for outdoor fun like the beach and barbecue parties without access to direct power.
However, you are building your audio system, pay close attention to acoustic feedback, as well as the direction and distribution of the sound.