The simplest PA system is a microphone or instrument plugged into a powered speaker
How powerful does my PA system need to be?
To answer this question, you need to know how you intend to use the PA system. Is it for an auditorium or a lounge? Are you giving talks to small groups or a large group? Once you know how you intend to use the system, the gear you need starts to fall into place.
Volume (space) and volume (loudness)
The PA system you want should easily fill the volume of your intended space, and sound loud enough for its intended purpose. The music system in a nice steakhouse, for instance, allows a singer/piano player to entertain the whole restaurant without blasting any diners out of their seats. A small dance club will have some high-powered subwoofers that help keep its customers coming back to the dance floor. To read how to install and design a dance club sound system, click here.
Another factor will be the number of people in attendance. The more people there are in the audience, the more the sound will be absorbed by their bodies, and the more it will become necessary to increase the volume to compensate.
This chart is a very rough estimate of how powerful a system should be, depending on the size of the space or audience. Use these numbers as general approximations — a 100- or even a 200-watt difference in the larger systems won't matter. When in doubt, pick a higher power value — extra headroom usually comes in handy.
|Recommended total PA system power for different venues and sound levels||Conference room, coffee house, school room;
up to 50 people
|Small auditorium, restaurant, bar;
up to 200 people
|Auditorium, theater, church, club;
up to 500 people
|Talking||50 watts RMS||200 watts RMS||500 watts RMS|
|Acoustic ensemble with vocalists||100 watts RMS||400 watts RMS||1,000 watts RMS|
|Jazz band||150 watts RMS||600 watts RMS||1,500 watts RMS|
|Orchestra and chorus||200 watts RMS||800 watts RMS||2,000 watts RMS|
|Rock band||225 watts RMS||900 watts RMS||2250 watts RMS|
|Techno/dance/hip hop||250 watts RMS||1,000 watts RMS||2,500 watts RMS|
Building a sound system
Now we'll examine each piece of equipment you might need for a sound system. If you're doing anything more than having a single person speak to a small room, you'll need most of these items.
Speakers are the workhorses of your system, and how many you need depends on what you're doing.
D.A.S. Action 12a is a 2-way multipurpose amplified speaker that can be used as a main speaker or monitor.
- Main speakers – Speakers come in two categories. Active speakers are powered, meaning they have amplifiers built into the speaker cabinets. All you have to do is connect your instrument or mixing board. Passive speakers are unpowered, which means you need to add an external amplifier. There are pros and cons to using each type of speaker, and it greatly depends on how you intend to use your PA system. For example, powered speakers are easier for travelling bands since all the processors and power are built in. Unpowered speakers are more flexible since you can choose how much power and what kind of processing to use in your system.
You can never go wrong with Cerwin-Vega! subwoofers. The EL-36DP is the first of its kind. A folded horn subwoofer packed with 2,200 watts executes the rich bass you need and the oomph you need to turn up a crowd.
- Subwoofers – Subwoofers are used to reinforce the deep bass sounds of kick drums, bass guitars, and synthesizers in order to add impact and excitement to any kind of music, but especially dance music. If you intend your PA for speeches and lectures, folk music, or a chorus, you probably won't need a subwoofer.
- Monitors – Monitors are speakers set up so musicians can hear themselves over the noise of the crowd and musical echoes from the venue, and thus be able to play better. The "sound guy" can usually benefit from having a monitor or headphones, too.
The 4-channel iNUKE NU4-6000 power amplifier packs 6,000 Watts (4 x 1,600 Watts @ 2 Ohms; 2 x 3,000 Watts @ 4 Ohms) into exceptionally lightweight and rack mountable packages. Now you can run your stereo full-range mains plus two separate monitor mixes with this one exceptionally lightweight, rack mountable powerhouse.
If you're running passive speakers with separate amplifiers, each amp should have at least as much or, better yet, more output power than the total wattage ratings of the speakers it's driving. Having extra wattage available (headroom) ensures clean, distortion-free sound, especially during sudden musical peaks.
The Behringer X32 Digital Mixer makes the transition from analog to digital an easy one. The 32-channel X32 gives you all the controls you're familiar with from the analog boards you're used to, and merges them with digital mixing advantages including total mix recall, built-in FireWire/ USB/ ADAT expansion, virtual FX rack, high-resolution 7" color display and more.
The mixer is the brains and control center of a PA system, and the coolest place to hang out. All of the sources of music and sound can be mixed and then sent out to the amps and speakers. The mixer has volume and tone controls for each input channel, allowing you to balance the individual signals and create a clean output signal.
Sound processors and equalizers
The Behringer FX2000 is single space rack unit features 71 algorithms, including true studio-grade stereo and 3D effects, and employs the company's RSM (Real Sound Modeling) technology to simulate acoustic environments with stunning accuracy.
Effects options include modulation, amplifier simulation, distortion and special effects, as well as effective dynamic and psychoacoustics processing. Performance is further enhanced through user-addressable high and low EQ and wave-adaptive Virtual Room reverb algorithms.
Most of the sound processing you need is likely built into the mixer and amp, especially if you're just starting up. Adding more complex processors give you even more control over the sound.
- Equalizers – Equalization lets you adapt your sound to a room's acoustics or finesse the sound of an instrument at a particular frequency. Some amps come with equalizers built into their input circuitry. Some mixers have them in their output sections. And of course, there are the outboard EQs that give you the greatest amount of control. Where a mixer usually has high, mid, and low tone controls (a 3-band EQ), an outboard equalizer can offer, for instance, 15 or 31 bands of control over the audio spectrum.
- Limiters – Another common device found in amplifiers and powered speakers, or as an outboard unit, is a limiter. A limiter imposes a set limit to the output level of the amplifier so it will never exceed the capacity of the speaker and damage it. A limiter is like a safety valve on a pressure cooker — you'll never have to worry about it blowing up.
- Effects – The output sections of many PA mixers feature acoustic effects like reverb and echo, which can be used to color the sound for dramatic and pleasant effects. If your mixer's onboard effects aren't enough for your needs, there are varieties of outboard effects devices you can get that can produce countless numbers of sonic effects.
For live sound applications, don't buy any microphone so expensive it'd give you a panic attack if it gets dropped or knocked to the ground. Expensive condenser and ribbon mics sound great, but belong back in a safe studio. Dynamic microphones offer more rugged and practical solutions for everyday use. (Condenser, ribbon, and dynamic mics get their names from the different ways they create signal.)
There are some essential accessories to get, in order for your PA system to function.
All of these sound components need to be connected somehow. The cables you need depend on the component. You'll find a variety of connector types on the gear and cables available.
Mic Stands hold your microphones where you want them. They come in many different configurations and shapes, so you can place and hold a microphone in any position and in any situation. A mic stand can be very short, for holding a mic on a desktop, for instance, or very tall, with an extension or boom arm and counterweight, for holding a mic up high and off to the side.
If your PA speakers are on the floor, it's pretty obvious that only the front row of people will hear the music properly, and they'll be in the way of everyone else hearing it. A way around this is to elevate each of your speakers with a speaker stand. Most PA speakers have a socket or other kind of holder, so they can be mounted on a stand. Just make sure the stand you pick is rated to hold at least as much as the speaker weighs.
Examples of PA systems
Here are a few basic diagrams of what most PA systems will look like. The real differences are in where the amplifier is located: built into the mixer, built into the speakers, or an external component.
This PA system uses a powered mixer to send power and signal to the speakers
Built-in power — Whether the amplifier is located in the mixer or in the speakers is a matter of choice. Either way makes setup and tear-down of the gear easier when you're on the road.
In this system, we're using a regular mixer and powered speakers, a popular arrangement for travelling bands and DJs
External amplification — The greatest flexibility comes when the amplifier is a separate component. This makes it easier to replace any piece of the system, but will require longer to set up. It's best for systems that are being permanently installed somewhere.
The traditional PA system uses an external amplifier to power passive speakers
Multiple amplifiers — PA systems for larger locations or very loud bands will need multiple amplifiers and quickly become more complex to set up. In systems like this, the most important piece of equipment is the sound guy.
Larger, more-complex audio systems might route the audio signal through a crossover into multple amplifiers and speakers
Put together the PA system that's right for you
As we mentioned throughout this article, be sure to read our other shopping guides for more detailed info for each component and browse our pro audio equipment offerings. If you have any questions not answered on our site, or don't have the time to research, contact our advisors. We are available via phone, email, or chat, and we are always ready to help.