Pro audio mixer buying guide
How to find the right mixer for your needs
Buck Pomerantz was born and raised in Philadelphia. His parents bought their first television set when he was born. He figured out how to run it by the time he was two. Besides athletics, his formative interests included electronics, amateur radio, music, and stage crew work. He got his BA in writing from Brown University. Then he joined a rock 'n roll band as their soundman and moved to Charlottesville, Virginia. After that venture failed, he spent time in Boston, New Orleans, and Berkeley. He worked in a music store in Austin manufacturing, installing, repairing, and operating sound systems for recording studios, clubs, and bands. He moved back to Charlottesville, ran a little recording studio and finally joined Crutchfield as a copywriter. He has 2 grown children and 3 grandchildren, but after a good nap he can still rock out.
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Mixers, like the 6-channel Yamaha MG06, let you blend the incoming audio signals into a balanced mix
A mixer is the brains and control center of a recording studio or PA system. It connects all the sources of music and sound to a studio's recording system or to the amps and speakers of a PA system. This article will help you figure out what size and which type of mixer is right for you.
What's a mixer do?
Every audio signal brought in gets custom blended with the other signals, and they all get directed out to where they need to go, either to amps and speakers or to a recorder.
Most of the knobs and sliders of a mixer are volume controls that send each input signal to the output it belongs to and at the volume it needs to be. The other knobs are mostly tone controls — each channel usually has a treble, midrange, and bass tone control.
A mixer also pre-amplifies weak microphone-level input signals up to the "line-level" that mixers and other pro gear need to process sound with the best signal-to-noise ratio.
How will you use your mixer?
Before looking through a random selection of mixers, you'll want to consider how you intend to use yours. If you're putting together a PA system that'll travel with a band, for instance, you'll choose a very different set of equipment than if you're creating a permanent installation for a conference room or church, or for a home recording studio.
Having extra input channels is smart, but not many people need something as big as Behringer's X32 32-channel digital mixer
How many input channels?
The first rule of choosing a mixer: You should always get a mixer with more input channels than you think you need. This will accommodate those special occasions when you need extra inputs and also allow for future expansion of the system.
Let's say your school or service club wants a lectern and a single microphone for presentations. You should consider a 4-channel mixer, so you could also play pre-recorded music before the presentations, and in the future add a couple of extra microphones for a panel discussion, for example.
Let's take a church PA system as another example. We need a microphone for the minister, mics to cover a 25-member choir with soloists, and a keyboardist. For the choir, you'll get good coverage with a solo mike front and center, two mikes on stands for the front left and right groups of singers, and two more mikes on stands covering the left and right singers in the back. That's five microphones for the choir plus one for the minister, and a channel for the keyboard. Seven channels total.
What this means is that for this size PA system, you could probably get by with a 7-channel mixer, but it'd leave no room for expansion or unaccounted options. Maybe you want to play pre-recorded music before the service — that's another stereo input. Maybe a guest musician could join the choir. Or another speaker could use a microphone while the minister uses his at the same time. So, to allow for expansion, you should figure on 3 "talking" channels, 7 choir microphone channels, and 2 stereo inputs; 12 total input channels. When in doubt, get a mixer with more input channels than you think you need — a 16-channel mixer would work even better for this kind of PA.
Another input feature you may want for your mixer is a USB input, so you can conveniently play music from your portable digital device without needing adapters or using up input channels. A digital mixer will probably already have a USB input as well as a second USB connection to use as an output.
The output section of this mixer covers most situations you'll need for live sound
All mixers have at least one set of main stereo, left and right, outputs.
- For recording, those outputs would go to an analog-to-digital (A/D) converter, and then on to your PC software or other recording device. Some mixers have built-in A/D converters and a USB or FireWire output ready for direct PC connection.
- For a live sound mixer, the main outputs send the final mixed signal to the amplifiers, which boost it, and send it on to the speakers for everyone to hear.
There are situations, however, where you will need other outputs to deliver the music to speakers not heard by the audience, stage monitor speakers or a DJ's headphones, for instance.
That's why mixers have monitor or auxiliary output "buses" that can be configured differently than the "house mix" — so singers can hear themselves clearly over loud drums and electric guitars and the DJ can hear his mix without noise from the room.
Buses transport the mixed signals to the outputs
You can think of a bus as a wire, inside a mixer, stretching all the way from left to right. The mixer assigns input signals to a bus, and the bus carries all the signals, mixed together, to an output. The main output buses carry the signal to the main speakers or amp, or to your recorder. There are often other types of buses that you can use:
- Monitor and auxiliary buses — Some larger mixers have multiple monitor and auxiliary outputs that can send different mixes to each monitor, so each musician can hear just what they want to hear from their monitor. Auxiliary outputs work the same way. They can be used to send the mix to recording devices, for example.
- Effects buses — An effects bus usually sends its signal out an "Effects Send," where it travels to an outboard effects device like a reverb or echo unit. The effect's output then comes back to the mixer through an "Effects Return," and gets blended back into the mix. Some mixers have built-in effects, so the signals' return path to the main mix is controlled by a knob.
- Subgroup buses — If you plan to record live, look for a mixer with subgroup outputs. These are preliminary outputs, before the main out, where you can group parts of the music together — vocals, drums, and keyboards, for instance — to record distinctly and clearly for later mix-down and processing. Subgroups also come in handy during live sound mixing, allowing you to control the volume of multi-miked parts like a drum kit or backup singers with one fader.
Meters and peak lights
Input channel clip lights help you set up a mixer's gain controls for the best possible signal. Output clip lights and meters let you keep an eye on the final mix's level, and warn you when it needs to come down. A lot of mixers have a monitoring bus, called "PFL" (pre-fade listen) or "Solo," which connects a channel directly to the output meter or LED array and shows you the level of the signal you want to monitor. A headphone jack is usually associated with this system so you can listen to as well as see the signal's level.
Insertion (I/O) and direct outputs
For extra-fine control over an input channel, there's a feature to look for called "insertion" or "I/O" (for input/output). A 1/4" TRS (tip-ring-sleeve) jack provides a way to insert sound processing devices into a channel's signal flow. This way, for instance:
- You could connect an audio compressor to a vocal channel to control its dynamics and smooth out any rough loudness peaks.
- Or, you could insert a noise gate in a microphone channel to clarify the mix and reduce bleed by automatically keeping the micropone off until the instrument it's miking starts playing.
- If you plan on recording multiple tracks at the same time, you may want to consider a mixer with direct outputs on each channel, so you can record each one separately.
Onboard EQ, effects, and other features
A few other features that you might see on a mixer:
- Onboard EQ — Most mixers have at least treble and bass EQ controls, and often midrange as well, so you can adjust the tone of each channel for clarity and fidelity.
- Phantom power — If you plan to ever use condenser microphones, make sure your mixer comes equipped with "phantom power." See our Microphones Buying Guide for more info about the different types of microphones.
- Onboard effects — Sonic effects like reverb and echo often add pleasantness to dry, lifeless sounds. Mixers that have onboard effects conveniently let you enhance your sound without needing any extra outboard equipment or cables.
Types of mixers
Besides all of the features and functions discussed above, there are different kinds of mixers to choose from as well.
All of the knobs on this Cerwin Vega CVM-1022 10-channel analog mixer make it easy to adjust the sound on the fly
Analog mixers are great for live sound, and can also often be used for recording. Each control on an analog mixer performs a single function, and provides you with a visible indication of how it's set. The positions of all the knob pointers and channel faders on a mixer give you an instant view of exactly what effects the mixer is performing on the sound.
If you don't like what you hear, you can reach for the controls and fix the sound without going through assignment or menu selection buttons first like you would have to do with many digital mixers. The number of adjustments you can make at the same time is limited only by the number of fingers you can use at once to turn knobs or push sliders. This is important in live sound situations when speed is of the essence.
Some disadvantages of analog mixers include the lack of any automation or programmability for complex shows, and the fact that relatively few analog mixers have any digital outputs for recording.
Sound is an analog phenomenon — musical instruments, ears, microphones, and speakers all perceive or create sound in analog fashion. However, the digital electronics used in signal processing and storage are smaller, cheaper, faster, and often of higher fidelity than analog circuitry.
Digital mixers have an analog-to-digital converter on every input, so all the mixing, processing, and signal directing occurs in the digital realm, for efficiency and advanced control capabilities.
The overwhelming advantage of using a digital mixer is the almost infinite sound configurations possible due to the power and scope of its software. It can remember and instantly recreate mixes performed in the past, which is an invaluable time-saver for touring bands and club venues. All audio processing can be performed via software, so no expensive outboard processing devices are necessary in order to produce good sound.
A special feature found in many digital mixers is the capability of programming automatic "scene" changes and triggering other devices, like stage lighting, to change their settings along with the music.
The Mackie ProDX8 uses your smartphone for its control surface
A cool feature showing up in more and more mixers is the ability to mix remotely via your smartphone, tablet, or other wireless device. These kinds of mixers allow their users to walk around a venue, while mixing, in order to ensure that the music sounds good everywhere.
A disadvantage of using a digital mixer is that making changes live, on the fly sometimes becomes a challenge when a menu or assignment button must be manipulated before the individual control is reached. And changing two or more settings at the same time is often impossible without pre-programming the changes.
Powered mixers, like this Behringer PMP2000D, give you power and control all in one box
As pointed out earlier, powered mixers include onboard amplifiers and processors, so all you need besides microphones and cords is a passive speaker or two for a complete PA system. A powered mixer is a great solution for a band playing small venues when space and portability are major concerns. Most powered mixers have a main amp and a monitor amp, to accommodate bands playing live.
Another great option, especially for touring bands, is a non-powered mixer and powered speakers. Just like with the powered mixer, having the amps built into the speakers means less gear to lug around and faster set up and tear down every night.
Check out our Live Sound Speakers Buying Guide for more discussion on this topic.
How to decide which one's for you
If the mixer you want is for a public address system permanently installed in a conference room or auditorium, you won't need any of the features used for recording or the effects used to enhance live music. If you're only going to use a mixer for a single purpose, be it live sound for a small band or church system, or recording at home, you should only consider mixers that have the specific features you'll need for the chosen job.
If, however, you'll be mixing live sound and recording, make sure the mixer you choose has all the features that facilitate those two functions. This means having both built-in audio effects, for live sound, and high-quality outputs, like USB, for recording.
If you have any questions or need more help before choosing a mixer, contact our advisors. They'll help you find the mixer that's best for your situation.