Audio Mixer Buying Guide
(Mixers | Posted 2011-03-07)
Fifty years ago, between the period when Elvis was drafted and The Beatles roared over to America, it wasn’t unusual to see a band playing a club using a Bogen PA system amplifier and Shure mini-mixer — a black box that had four volume controls on its front panel, along with a master volume and VU meter. Back then, it wasn’t uncommon for a band to be able to play a club with that 50-watt Bogen, two PA columns and one microphone for each singer. Microphones weren’t placed in front of amplifiers or drums, and volume levels were sometimes lower than what you’ll hear in your neighbor’s backyard barbecue in 2011. However, these days —unless you’re a solo act that uses one guitar and a microphone— you’ll need a mixer at some point in your career. Typically, the plethora of mixer choices in the modern age is both a blessing and a curse. This guide is designed to help you navigate through the sea of possibilities.
Powered or unpowered?
Although it’s possible to buy a powered mixer we’re going to assume that you’re planning to buy PA amplifiers and a mixer separately, or powered speaker cabinets and a mixer. We’re also going to assume that you won’t try to run your own sound from the stage. This means you’ll need a “snake” (pictured at right) to carry signals to the mixer and back to the amplifiers. In sound reinforcement terms, a snake is a thick housing for multiple cables that is used to route many signal sources from the stage to the mixer, which is usually located among the venue’s seats. Instead of running dozens of individual microphone cables through the audience area, the classic snake has a box at the stage end with microphone and other signal source connectors. Three-prong XLR connectors are most common, but there may also be 1/4” connectors. The wires from the stage are bundled into the snake housing and they exit the mixer end of the snake individually, ready to be plugged into individual mixer channels. The number of channels in the snake usually corresponds to the number of channels in the mixer, which commonly are configured in multiples of 4. For modern club applications, 24 is about the minimum number of channels for a mixer. Why so many?
Let’s say that we’re working with the classic four-piece group setup of two guitars, bass and drums. Each member sings, so we’ll need four channels for vocals. Well also run microphones on both guitar amps and the bass amp. So we’ve used eight channels already. Now let’s say that our drummer uses a 5-piece kit (bass, snare, two mounted toms, a floor tom, a high-hat cymbal, one crash cymbal and one ride cymbal. At a minimum, an engineer would want to place one microphone on the bass drum, one on the snare and use a single overhead microphone to pick up the tom toms and cymbals, meaning a total of 11 channels. However, for maximum control of drums sound, most sound engineers prefer to place one microphone on each drum, one on the hi-hat and a minimum of two overhead. That means you’ve used eight channels for drums as well, so you can see how 16 channels may be barely enough for even a small band. If you have keyboards or if one of your guitarists also plays an acoustic occasionally, you may use as many as five more channels to accommodate their needs. Thus, although it may initially seem like overkill, a 24-channel board may be a starting point for bands. For a good sound engineer, running many microphones allows maximum control of the sound.
Analog or digital?
Since we’ve ruled out using a powered mixer, your choice of will be between an analog or digital board. Analog mixers continue to be popular for their ease of use and relatively low cost. A 24-channel analog, non-powered mixer can be purchased for around $1,500 (USD), while a comparable digital board would likely cost around $2,500 (USD). If even $1,500 sounds prohibitive for only a mixer, consider starting with a board having fewer channels, then adding a second board when money becomes available. The great advantage of a digital mixer is its flexibility. For example, most digital mixers allow various settings to be saved and recalled at the touch of button. These settings include not only channel volume, but EQ, effects and more. Sound will also be typically be cleaner with a digital mixer, meaning a better overall sound for not only the audience, but also the band.
No matter which type of mixer you chose, channels are likely to be laid out vertically, side by side. Each vertical channel strip likely will house identical switches, knobs and sliders, all of which perform specific functions. Although some less expensive mixers with a small number of channels may use a rotary volume knob on each channel, most professional mixers use “faders” (pictured at left) that slide vertically, increasing volume as they are moved up. A mixer will also have some type of tone control knobs.
Inexpensive mixers may have one Bass knob and one Treble knob; more advanced boards may add a single Mids knob, and high-end models will most often offer midrange controls that allow the user to select center frequencies for maximum control. Tone controls typically are Boost/Cut. That is, a center position allows a flat signal; turning the knob to the right increases the amount of tone while turning the knob to the left decreases it. If you have a guitar with an active preamp that allows boost or cut for tone, it's the same principal.
Each channel also usually has some kind of “pad” control to adjust single levels — either a pushbutton with a preset value or a continuously variable knob to boost or cut signal level — and a mute pushbutton to stop sound from being output by that channel. An overload LED also will tell you if you’re driving the channel too hard. A “Solo” button allows your sound person to mute everything but the channel on which the “Solo” button is engaged. This allows the engineer to quickly find problems, such as buzzes or other noises.
Finally, each channel will usually have an effects level control (for reverb, echo, compression or other effects) and a Monitor send volume, used to control the level of signal that is fed to onstage monitor speakers, which face the band rather than the audience. Although monitors are taken for granted today, remember that The Beatles played even outdoor stadiums without having any kind of monitor system. Although larger bands may be able to afford a separate monitor mixer, it is possible for a band to get a decent monitor mix using what is available from the Front-of-House (FOH) mixer. In many cases, a couple of wedge monitors in the front line will suffice.
A word of advice to young players: Simply because you have stage monitors doesn’t mean you can crank the volume of your amplifiers. Any good sound engineer will tell you — low stage volume makes for an easier mix and happier ears. Listen to your sound person so the crowd can be able to listen to you.
Master controls section
Depending on its level of sophistication, your mixer may have a separate master control section with several sub-areas. The picture at right shows a typical mixer with master controls section on it's right side.) At the very least, this Master area will contain a master volume slider that controls the overall level of the sound being fed to the crowd and some kind of output level display -- either a VU meter with a needle display or a series of colored LEDS. The master section also typically will contain controls various outboard effects such as echo and reverb, and a master monitor volume slider plus a “talkback” section that allows the engineer to talk to the band through the stage monitors. More sophisticated mixers will allow the engineer to send separate monitor mixes to band members.
Where do I start?
Our recommendation is to find a local music store whose personnel can help you tailor a system to your needs. It’s also handy to be able to go to a place nearby for help rather than to spend hours on the phone with an online retailer's support people. The best music or sound companies will even come along to your gig to help you set up and tweak your system if that’s required. If such a store isn’t available locally, please do take advantage of the customer service offered by major retailers such as American Musical Supply, Musiciansfriend and Sweetwater, all of which have staff ready to answer your questions and make recommendations.
To help you get started in your search, here’s an alphabetical list of manufacturers which have established reputations for quality and reliability.
Allen & Heath
Last but not least, don't forget that MGR offers a Forum section where you can ask for advice and help from professionals and gigging musicians like yourself. And don't forget to search our reviews database to see if the equipment you're considering has been evaluated by MGR or a user.