Edit Points: A Sound Investment

by Mark Bosko
January 1995

Imagine this: you're a freelance videomaker, and you've landed a great job covering election night for a local TV station. The job requires you to provide the equipment and crew. As you unload equipment at the packed voting center, Mr. On-Camera has a question. "How are you gonna mike the interviewees?"

The teed-off talent assures you that one mike will not be sufficient. Luckily, you have a spare (just in case), but now you have a problem. Two mikes, one input.

You need an audio mixer.

What is a Mixer?
An audio mixer is a device that combines (or mixes) several independent audio inputs into one signal. Say you are recording an interview in which two or more people are talking. You can feed each of the different microphone inputs into a mixer where the signals will merge into one. The final output of the mixer is a single mono or stereo signal. You can then record this onto videotape.

There are two basic types of mixers: passive and active. Passive mixers are very simple machines. They combine a number of individual inputs into one output. But the passive mixer does not allow for amplification of either the input or output signals. Passive microphone mixers are very popular with video enthusiasts. Most field production situations require the use of only two mike sources--the interviewer and the subject. A passive mixer is a simple solution.

When you need control over the amplification of each of the incoming audio sources, look to an active mixer. Each channel on the mixer has its own potentiometer. Commonly known as a pot, this control increases or decreases the amplification of a signal. In addition to these individual gain controls, one additional pot controls the master gain. This governs the overall amplification of all the channels together. Many active mixers, low and high-end, come equipped with VU meters so you can set levels for each individual input as well as for the master gain.

Depending on the type of mixer you work with, you may have two, four or more channels to work with. Four channel mixers are very popular, satisfying many video/audio needs. They are able to combine four separate audio inputs into a single output signal. The inputs may be mike level or line level, amplified or unamplified, or some switchable combination of all three. Often, the output level is switchable too, which means you can send the signal to a VCR as a microphone-level or a line-level signal.

While the opening example describes a portable mixer, audio mixers are built for the studio as well. They function in much the same way. Studio mixers offer much more in terms of features. The accompanying price tag reflects this fact.

Why Use a Mixer
You may be thinking you'll never find yourself in the aforementioned scenario. You're strictly a social occasion taper--weddings, anniversaries, bar mitzvahs, and the like. The sound you need can come from the on-camera microphone. If the occasion calls for more versatility, you can always plug a mike into the auxiliary input. Sooner or later, however, you're going to want to up the quality of your productions. When this happens, a mixer should be the first item on your shopping list.

Placing mikes on the minister, bride, groom and organist lets you capture the best possible sound during the ceremony. You don't have to worry about a baby in front of the camera drowning out the vows. A four channel mixer can handle all of these inputs, providing a nice mix down into one signal. If the mixer has separate pots on each channel, you can effectively boost the bride's faint voice to match the jittery chirps of her soon-to-be hubby.

Say you are a sports video enthusiast. Why would you need a mixer for a production? Here's what Alan Giullito of Cleveland-based Sports Videos has to say on the subject.

"For the past six years, I've been taping the local gymnastic meets. This has become something of an affair in our town. More than 200 children compete. That means more than 200 potential tapes to sell!

"In the beginning, I simply set up my camera in an advantageous position to get coverage," says Giullito. "Sound was recorded through the on-camera mike. This worked O.K., but the sound quality of the tapes really lacked something. I wasn't producing anything more special than what a parent with a camcorder could do. And when the price of camcorders fell, so did my sales."

Giullito knew he must deliver a more professional product. Investing in a new camera wasn't an option. He chose to work on the audio problems.

"When you watch sports events on TV, the audio makes you feel like you are right beside the athlete," says Giullito. "If you just heard assorted crowd noises, you wouldn't be able to stand it. That was the problem with my tapes. I got the chance to talk with a professional sports cameraman at a seminar. He explained to me how TV crews use multiple mikes and mixers to record all the sounds associated with a particular sport. That got me thinking."

The Upgrade
Giullito's first move: purchase some microphones. "With gymnastics, much of the sound of the event comes from impact with the floor. Eventually, I bought several contact microphones and placed them in different areas around the floor. They function by picking up sounds generated by contact. It all depends on the activity. With something like the floor routines, there's a lot of contact with the mats.

"I also got my hands on a slightly used, but high-quality shotgun mike," says Giullito. "This let me get the sound from the parallel bars and rings, places where contact mikes wouldn't work. Finally, I fed my own mike to the announcer's table. Before, I would pick up the distorted sound of the announcer as it came out of the loudspeakers. Now his sound was clean and balanced.

"All of these new mikes fed into a portable audio mixer. The model I purchased had a separate pot on each input. This was important. It let me adjust each individual sound input. And boy did the sound vary! Sometimes the contact mikes were really soft and the shotgun super hot. The mixer really brought the production quality up quite a few notches. I now again offer something the average Joe can't do. And my sales prove the investment paid off."

Again, the sports field isn't the only place for a mixer. "I do a lot of music videos for local bands," begins Rodger Hoskin, freelance videomaker. "And without a mixer, I couldn't even begin."

Hoskin shoots low-priced music videos that bands use to get club bookings. "They're very simple productions. Performance-based videos, set on a stage. I feed all of the miked singers and instruments into the mixer, just like a live set up. The output goes to my deck. Sometimes I feed the output to an video/audio effects mixer. This lets me shoot with two cameras as well," says Hoskin.

"I have to use the separate audio mixer because the A/V mixer only has two inputs," Hoskins continues. "I went from two-track audio capabilities to eight after picking up a mixer. The experimental freedom the unit allows me has definitely been worth the cost."

Optimizing post-production sound is another popular use for a studio mixer. You can add numerous tracks of audio without multiplying the generations of the video. With a time-coded master, you can strip off the audio and remix it with as many auxiliary audio sources as your mixer will allow. When the audio work is complete, you can resync it perfectly with the video via the time code. Any Hollywood movie is a great example of audio mixers at work. Some of these technical marvels are playing over 100 channels of audio at once.

What to Consider
When choosing an audio mixer of your own, there are several features to consider.

First, of course, is cost. It'd be great to go out and buy the costliest mixer available. But do you really need it? You're guaranteed high quality and performance by dropping the big bucks. Sometimes, however, your needs don't demand so much. If you are only going to use the mixer in field interview shoots, all the bells and whistles really aren't essential. In fact, they may even get in the way.

"I have a buddy," relates Hoskin, "who picked up a pretty high-end mixer. He uses it both in the studio and in the field. Once in a while he'll use some of the fancy functions in the studio. But when he takes that monster on location, it really drags him down. He thought he'd use the fancy effects more. That's not the case. His bulk of jobs are field interview situations. He could've gotten by with a low-priced, four-channel unit."

The number of inputs on the mixer is another important consideration. Four channel mixers serve many purposes on the road. And if a crisis arises, you can always get by with some Y adaptors.

To determine how many channels you will need, think about the future growth of your business. Are you planning to work on larger scale projects than you currently produce? If so, will the mixer you buy today serve your needs tomorrow? You don't want to get stuck with a piece of equipment that is inadequate for your purposes. For sophisticated projects, such as broadcast-quality work, you might want to try an 8 or 16 channel mixer on for size.

Microphones and other audio sources tend to have a variety of connectors. Professional mikes use XLR connectors. Mid-level and lower priced audio gear may sport mini-plug, RCA/phono or phone plugs. Make sure the mixer's input jacks can handle your outputs. If you are not working with professional quality audio equipment with standardized connectors, a set of audio adapters can solve your input problems. This collection enables you to adapt any type of microphone or cable to any type of input connector.

What's Out There?
For the budget-conscious, there are several mixers available for less than $80. Azden's CAM-3 ($60) features three inputs, switchable for mono-line or mike. At $79, Radio Shack's 32-1101 is a bargain. It sports a combination of five stereo, mike and phono inputs. Another nice touch is the linear fader (slider). Easier to control than the rotary type, linear faders let you quickly determine the status of the mix set-up at a glance.

In the $500 and under price range, Fostex's 2016 gives the user 16 mono line inputs. Its digital meters make for accurate signal monitoring. Or you might try the eight-input MS1202 by Mackie. Audio sources can be mono, stereo or mike, with equalization available on two frequency bands. Both the Yamaha AM802 and Peavy's Unity 1000-8 offer 8 inputs, equalization and slide faders.

If you've got some cash to burn, you may want to check out the M-1016 from Tascam ($1500). It has 16 inputs for a variety of mixing duties. For $100 more, you can get your hands on Carvin's DX-2442. An audiophile's dream, the DX offers 24 inputs, digital meters, stereo output and linear faders. This unit should handle all of your audio needs now and in the future.

Get Mixing
Considering the large selection and affordability, buying an audio mixer is becoming a must do for any serious videomaker. Adding one to your collection of gear will do two things. One, it will drastically improve the quality of your productions. And two, it'll make you wonder why you've waited so long to get one!

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