A field audio mixer is the key to creating perfect audio. These machines give you more control to mix your audio on location, thereby dramatically increasing the overall production quality.

An audio mixer combines sound from two or more input devices and lets you control the mix. For example, say you are going to shoot a PSA about a local college. You want to capture the "feeling" of what it's like to be on campus. You start by recording only the natural, background sounds of the grounds, the wind in the trees, the birds chirping, the trickling of a waterfall nearby. You want to capture the sound of the football team practicing on the field at a distance. As you enter the main building, you want to capture the sounds of students walking in the halls, doors opening and closing, perhaps a voice over the loudspeaker.

Now, consider what you'd do if you want to add snippets of conversations among students and some sound bites to the natural sound? What if you also want to add some ambiance music into the mix, and then fade in even more music, perhaps from the school band, as a narrator begins to speak?

Another scenario might be that you are recording two people on location at the same time, who are each hooked up to different mics. But Subject A has a big booming voice while Subject B has a tiny soft voice. The ability to get a correct level of each separately in the field is crucial, you might not be able to split them later on during editing and what a nightmare that would be trying to bring one level up and take the other down with extensive audio tweaking.

Why you need a Field Audio Mixer

Now things gets tricky, unless you use a field audio mixer. With a mixer, you have the ability to monitor, adjust, separate, mix, and blend two or more mics. You can even do some damage control by eliminating hum, wind, and proximity noise. You can send level signals out to your camera or to a separate recorder, or both simultaneously. In other words - you have options.

What Kind of Audio Mixer Should You Buy?

Understand the usefulness of a field audio mixer is just the beginning, so now that you know you can use one to enhance your video work, might need some help picking one out. There is a wide variety of field mixers to choose from and the one you chose largely depends on what type of movies and videos you make.

When shopping for mixers, it's important to understand the features you need. Make sure you get one with a headphone jack, so you can monitor your signals. Headphones are an invaluable tool if there is noise and other distractions while you're recording. Another handy feature is a preset option, so that you can quickly set your sound level exactly where you want it to be. You'll want at least two mic inputs, either XLR, 1/4" phone, or mini plug, depending what type of mic you have.

If you think you might be working with some complex soundtracks in the future, consider the mixers that have multiple input and output channels. This enables you to assign incoming sound sources to any output. Instead of having all levels going to the same outputs, you can add variety to your mix. Look for a mixer with separate microphone and line-level inputs, where each channel has a switch to change the input between microphone level and line level. This will make the mixer more versatile and allow you more flexibility in the edit room. A VU Meter is an absolute necessity to monitor levels and adjust them accordingly. Also, if you are going to mix your audio live in the field where there are no electrical outlets, your mixer must run on batteries. Battery-powered mixers are smaller and lightweight, ideal for use in reality shows, news, documentaries.

How Much Will it Cost?

An entry-level mixer like the 302 Compact Production Field Mixer by Sound Devises is a professional, compact, three-channel audio mixer designed to meet the demands of professional film, ENG / EFP, and broadcast applications. Features include three balanced XLR inputs that are capable of accepting mic or line-level. Three AA batteries or external 5-18 VDC power source powers this unit.

In the mid-level category, SignVideo's ENG44 is a rugged, lightweight, compact mixer. It has four balanced mic/line XLR inputs, stereo paired XLR outputs, auxiliary 1/8" unbalanced mic level output jack, VU meters, master gain control, and it runs on four AA alkaline batteries.

For higher-end productions, there is the Wendt X4. It has many features, including four-balanced XLR inputs, two balanced XLR mic/line outputs, VU Meter, and Stereo 6.5mm 1/4" headphone. It runs on eight AA Alkaline batteries for up to 15 hours.