The EM Poll

P.A. 101

Mar 14, 2008 3:24 PM, By Emile Menasche

           

HOW TO CHOOSE THE RIGHT SOUND SYSTEM FOR YOUR NEEDS WITHOUT TEARS

Illustration: Phillip Brooker

Sound reinforcement may not be the most glamorous area of the music industry, but it's certainly an important one. If you want your performance to reach your audience whether you're playing in a church or a coliseum you depend on the P.A. system to get it there. Having a good understanding of sound-reinforcement concepts will not only assist you in dealing more effectively with your own system, it will also help you make informed gear purchases and better communicate your sound needs to other musicians and engineers at your gigs.

In this article, we'll cover some basic ground about the most important sound-reinforcement components and key concepts. So whether you're new to gigging or are a longtime musician, we'll help you raise your P.A. IQ.

First, let's review the obvious stuff. Every sound-reinforcement system consists of three main elements: mixer, amplifier, and speakers. These elements can be used to create a wide variety of systems, from the all-in-one units designed for solo performers to the full-blown, multikilowatt road rigs that touring companies carry. In all cases, the basic mission remains the same: to blend and process signals so they're loud enough to hear, clear enough to understand, and pleasing enough to keep the audience interested.

The kind of system you need depends on the makeup of your band and the size of the venues you're playing. To a lesser degree, the type of music you perform and the audience's composition are also factors. As you evaluate your choices, you should ask yourself the following questions:

How many inputs do I need? Remember to count each vocal microphone, as well as all instrument mics and line-level signals that will go through the sound system.

How loud do I need the P.A. to be? Are you hammering out rock 'n' roll in a noisy, crowded bar? Will the singer be competing against a wall of Marshall amps? Or are you just adding some depth to an acoustic instrument so the people in the back of the room can hear it?

I know what I want the audience to hear-how can I control what the band hears? Onstage monitoring is almost as important as projecting the sound to the audience. Before buying a system, figure out how many separate monitor mixes you'll want and how many monitor speakers you'll need based on the physical dimensions of your stage setup. For example, a four-piece band playing small clubs usually needs at least two monitor cabinets-one for the front line and one for the drummer. Adding a second front-line monitor would be a big improvement.

What else will I be doing? If you plan to take breaks, you'll probably need a way to pump prerecorded music into the house. You may also want to record your performances, in which case you might want a mixer flexible enough to route different mixes to the house and to your recorder. (For more on what you need for live recording, see "Caught in the Act" in the May 2000 issue of Electronic Musician.)

Once you've answered these questions, draw a chart that maps all the inputs you'll need. Be realistic. If your band specializes in small clubs, you probably won't need to reinforce the guitar and bass amps with the P.A. If you'll be playing larger stages (such as outdoor venues), you'll probably need to pump those instruments through the system, and the band members will most likely require more monitoring than in a small club because they're going to be spread farther apart.

If you're a gigging musician looking for a system, you have a choice of three main types of rig.

All-in-one systems. These units combine a small mixer (sometimes as few as three channels), a power amp, a speaker system, and often some effects in one easy-to-carry package. Some keyboard amps and acoustic guitar amps qualify because they can handle mic and line inputs, and they offer a wide enough frequency response to reproduce a variety of instruments. Solo performers will find these units useful because they're easy to transport, can be set up quickly, and are simple to operate. Generally, these types of systems have only a few inputs: a microphone jack, an instrument jack, and an auxiliary input for a CD or cassette deck. Many of the newer models also provide onboard effects. In large venues or in band situations, you can employ an all-in-one unit as a personal self-powered monitor.

Powered mixers. Offering a nice balance of integration (mixer and power amp in one unit) and flexibility (expandability options and the ability to choose your own speakers), powered mixers are the choice of many club-level acts. There are two common types: heads that look like large power amps with integrated mixing controls, and consoles with built-in power sections. Both versions generally offer a full array of line and mic inputs, multiband EQ, aux sends and returns, fold-back inputs (for the CD player), and a master-section graphic EQ. Many newer models have stereo power amps, built-in digital effects, and recording outputs.

Mixing consoles with separate power amps. The bottom line is that most powered mixers are designed for small acts with relatively simple needs. Unpowered mixers, on the other hand, come in all shapes and sizes-including huge behemoths-and offer a wider variety of outputs than you get with most powered mixers. Therefore, using an unpowered mixer and separate power amps is by far the most flexible way to go; you can mix, match, and upgrade the individual parts of the system as necessary. On the downside, you need to do more wiring with discrete components, and larger consoles often are complicated to use, hefty, and a pain to haul around.

Both types of mixers offer main, monitor, aux, and effects buses. In addition, many unpowered mixing consoles offer direct-channel outputs (useful for multitrack recording), multiple aux sends on each channel, semiparametric or fully parametric EQ on each channel, individual channel inserts (useful for plugging in outboard gear such as compressors and gates), and submix buses that can route an alternate mix to a monitoring system or 2-track recorder (see the sidebar "A Typical Mixer Channel").

Digital mixers offer many features that are beneficial for live performance. Configurations vary, of course, but you often get flexible EQ, onboard dynamics processing, and snapshot automation, which allows you to set up and store a mix for each song. Some digital mixers offer individual channel delay, which is useful for correcting phasing problems between speakers that are installed far apart on the stage. As with analog consoles, you can rack-mount some models, such as the Yamaha 01V.

Before choosing a digital mixer, however, make sure it has enough analog inputs to meet your needs. The typical low-cost digital unit offers a mix of analog and digital I/O. The 01V, for example, is a 24-channel board, but only 16 of those channels have analog inputs.