Sound Advice: Mix it Up!

My first experience in video involved producing audio for a one-hour, live, multi-camera television program. Many times, there were dozens of microphones, both wired and wireless. And don’t forget audio playback, from both cassette tape and reel-to-reel. Don’t laugh; it was a really long time ago! The point is, we had to combine audio elements from a wide variety of sources, on the air, live, every week. And sometimes, it was scary. By contrast, much of the video sound I deal with today is single or, at most, two microphones. One person serves as director, camera operator and audio mixer. And if there’s a mistake, the scene can be done again – comfortable territory for a video producer.

If the thought of mixing audio from multiple sources makes your palms sweaty, relax. There are some specific tools and techniques you’ll have to learn, but the finished product is worth the effort and the experience will serve you well for years to come.

The Venues

Before we discuss the hardware required to create a multi-microphone audio mix, let’s consider the various types of events and locations where you might need such a mix. In generic terms, they fall into three categories, but there is quite a bit of overlap depending on the specific event you’re working.

First is the play or theatrical presentation. These affairs often require several concealed wireless microphones in addition to broad area microphones, music and sound effects feeds. Plays are often an hour or more in length, so you have to make absolutely sure everything works beforehand, and will continue working throughout the presentation. Balancing all the various sources is quite a challenge, but, fortunately, there’s a script to follow. Theaters are quite comfortable with technology, so your presence won’t be much of a distraction. But, you’ll have to make fast friends with the stage manager and technical director as well as the actors and others involved in the production. Their acceptance of you and your equipment is critical to the success of your mix.

A second type of event that requires multiple microphones is a concert. Whether classical or heavy metal, you’ll need a variety of instrument and vocal microphones along with stands, cables and other hardware. Since these productions often have their own sound personnel, one possible solution is a unique tool called a splitter snake. This is a special box that splits each microphone into two or more copies of the same signal. Splitter snakes allow the house sound engineer to create one mix while you receive a duplicate of everything to make your own custom mix. One of the biggest problems for a video sound mixer in a concert situation is isolation. You need a quiet place to create the proper mix, but concerts don’t offer much seclusion. Your options are simple – set up your equipment in another room or use headphones. Neither situation is ideal, but both are workable.

Yet another multi-microphone event is a conference or seminar. These occasions are often recorded on video for later sale or simply to create a document of the event. This may be the most intense of all the categories for one simple reason: you never know what will happen next. For instance, a round table discussion may involve a dozen or more microphones for the panel, a commentator microphone and a wireless or two for audience questions. Unfortunately, you can’t have all of the microphones wide open all the time, but you could miss some critical information if you shut off the ones that aren’t used all the time. And there is no script, so you’ll have to be on your toes.

Of course, there are events that combine some of each of these components. A modern church service, for instance, may include a dramatic presentation and music from a band in addition to the sermon and other more traditional elements. It’s common to see 32 or more inputs in many church sound systems.

The Tools

Now that you’re familiar with where and what you might mix, let’s look at the tools of the trade. First, of course, are microphones. Your existing handheld, lapel and wireless microphones will all work perfectly in a multi-microphone situation. Even a shotgun microphone can be useful in certain circumstances such as distant voice pickup. Unfortunately, you probably don’t own multiples of each microphone or type. If you’re like most solo video producers, you have one each of the microphones you use most often and that’s all. If you plan to mix audio for many complex events, it’s worthwhile to purchase your own equipment. If you’re planning a one-shot mix or will only do this occasionally, it’s better to rent (or borrow) the equipment you need. The downside to renting is that you’ll never have the same setup twice, and you’ll need to spend some time with each piece of equipment to ensure it works properly and plays nicely with all the other equipment.

Next, you need a mixer. The number of required inputs is dictated by the specific event you’ll mix. Whether you need four inputs or 40, there is no shortage of affordable, high quality mixers on the market. Behringer, Carvin, Mackie and Yamaha, along with other manufacturers, all offer a wide range of features at attractive price points. Regardless of the brand of mixer you use, make sure it has a few common features. First on the list are balanced microphone inputs with phantom power. These will accommodate any professional microphone, including condenser microphones that require external power. Next, make sure the mixer has sliders for each channel’s main volume. Although knobs are more traditional and cheaper to manufacture, sliders are much easier to operate and it’s easy to get a mental image of your mix at a glance. Finally, make sure your mixer has some basic audio meters and a headphone jack with a volume control. Although common today, these two features were considered optional on many mixers just a few years ago.

In addition to the microphones and mixer, you need a solid pair of headphones, some microphone stands and a boatload of cables. Obviously, you need a cable for each microphone, but maybe that’s not enough. Many times, you need just a couple more feet of cable to get to the source. Besides, a few spares never hurt anyone.

The Mix

In theory, a multi-microphone mix for your video should be identical to a mix created for live sound in the venue. After all, a good mix is a good mix, right? You should be able to take the house mix, add an audience microphone or two and you’d be set. In practice, though, the two are quite different. Due to room size and acoustics, sound system issues and stage monitoring, the house audio mix is often a compromise of levels to make the system sound good as a whole. If you record that compromised mix on your video, you’ll hear drastically different volumes for various microphones and an imbalance of instruments, music and other audio elements. Alternatively, an independent audio mix can be closer to the ideal balance of voices and instruments, allowing you to make complimentary changes that won’t affect the sound in the venue.

Once you’re familiar with all the hardware and setup of the microphones and mixer, audio mixing becomes more art than science. As a result, it’s difficult to distill years of mixing experience into a single paragraph, but there are some basic things to listen for.

Once everything is working properly, rely less on the meters and knobs and more on your ears to determine the proper blend of sources. If one voice seems louder than the others do, it probably is, regardless of what the meters tell you. Sometimes, these differences can be corrected with tone adjustments rather than volume changes. If possible, mix and record a rehearsal before the actual event, then play the audio back on a simple sound system.

Listen for specific sounds that stick out or are covered by other sounds. Take notes as you listen and touch up your mix accordingly. If you have trouble keeping an even mix, try adding an audience microphone or two to your mix. The sound of the room often smoothes over some of the rough places and adds an air of excitement to the final mix.

[Sidebar: Location, Location, Location]

Where you mix is just as important as the equipment you use – maybe more important. Even though audio isn’t technically visual, a vantage point inside the venue is important, both for ease of cabling and to help you keep an eye on things. A birds-eye view of things will help you catch microphones that need to be turned on or off as well as blown cues and production blunders, improving the quality of your mix.

[Sidebar: Help!]

Maybe all this audio stuff is just too much for you to handle. After all, you have enough on your hands with the video side of things. It’s perfectly all right to recruit someone else to take care of the audio duties. In fact, it may be easier and better to find someone who already owns all the necessary equipment and knows how to use it. If they mix audio for festivals, conferences or even church events, they’ve already learned many of the hard lessons and can spend their time finessing the mix, rather than learning the ropes from scratch.

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