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!
