When you have a video production that begs for creative, high-impact audio, the limited audio abilities of
your camcorder may not cut it. To put together the soundtrack you know your video production deserves,
you may need a multi-track audio recorder. Modern audio/video post-production is totally dependent upon
multi-track recorders to layer up a number of audio tracks. You can do this as well, using techniques like
“bouncing tracks” or “sound-on-sound” to provide professional audio-for-video when a limited number of
tracks are available on your machine.
A multi-track recorder allows you to individually record, re-record, modify or erase a number of
audio tracks that are perfectly in sync with each other. Afterwards you can combine or “mix” the multiple
tracks into your high-impact mono or stereo soundtrack.
The latest software-based multi-track audio systems use a hard disk as the storage medium. These
systems are becoming more common and less expensive, making them the wave of the future for multi-
track audio. Their flexibility makes the job of producing complex audio soundtracks even easier. It’s like
putting a puzzle together one piece at a time until the whole picture emerges.
Putting the Pieces Together
Once you understand the concept of multi-track audio recording, the process of putting together a
multi-track audio soundtrack is not hard. In fact, it’s as easy as 1, then 2, then 3…, right on up to the limits
established by the number of tracks you have to work with.
If you are using time code or MIDI to keep both your video machines and audio tracks in perfect
synchronization, you might start with a sync track. More commonly, you are operating on a budget, and
you will start by dubbing the audio track from your camcorder onto one track of the multi-track recorder.
Other times you may just want to narrate a video clip, or maybe you want to look at the video and create
original music or sound effects to enhance the visual images. The choice is yours.
You “lay down” the first track by putting that track number on the recorder into the record mode.
After that, you just go to the next track number on which you wish to record a signal and put that track into
the record mode. By putting another track into the record mode, the machine will automatically switch into
the sync mode, assuring that your subsequent tracks are in sync with the previous tracks.
A typical audio-for-video soundtrack might include music, narration and sound effects. You can
weave the various elements of the audio track in and out as is appropriate for the production by controlling
the various individual audio tracks during mixdown with your audio mixer.
The mixing console is a device that lets you be creative in combining the individual audio tracks you
recorded earlier. Small four-track cassette multi-track machines will usually have a built-in mixer that
allows you to mix the tracks right on the machine. These machines range from very basic, with a barely
functional mixer, to quite elaborate, with a high-tech mixer whose function and abilities make the unit a
mini-studio in a box. Cassette four-track machines are still the least expensive way to begin doing multi-
track audio production.
Once you jump up into eight tracks or more, you will need a mixing console. This is true with
either the analog or digital multi-track machines, though a few hard disk recorders do have built-in mixers
or mixing software for use with a computer. The console allows you to input microphone signals and line-
level signals (from camcorders, CDs and other sources) and mix them onto the multi-track. When you have
all the tracks you need on the multi-track, the console then serves to do the mix, combining the individual
tracks into one audio soundtrack.
If you are working with a limited number of tracks, you can “bounce” them to free up room. With
a four-track machine, for example, you can combine (mix) three tracks to the blank fourth track, leaving
the first three tracks available for more audio signals. Once you do the bounce, you can’t change the
relative mix of the elements–they’re combined for good as soon as you erase and reuse the first three
tracks. This technique gives you six tracks of audio from your four-track machine. You could bounce again
for even more tracks, but the audio quality begins to suffer on analog machines as each bounce puts you
another generation away from the original signal. Noise builds up with each generation, because the audio
signal carries a certain amount of tape noise.
A better way to squeeze in another track is to do “sound-on-sound” while mixing the first three
tracks to the fourth. As you do the track combining mix, you can also mix in another original audio signal
at the same time. This audio signal merges with the signals from the first three tracks, hence the term
Staying in Sync
To sync–or not to sync–may be the big question as you step up to a multi-track recorder. If you are
doing a lot of serious video production, you should only consider multi-track equipment or systems with
synchronization capabilities. If, on the other hand, you only plan to play around with the concept, I suggest
a small cassette four-track with a built-in mixer. You can then do short sections of audio-for-video
productions and manually sync it with your images. If you put your video camcorder and your audio
recorder on pause at a given point, you can start both at the same time and achieve a pretty good sync for
short sections. This won’t work if you have lip movement to sync to.
With time-code or MIDI synchronization, you can go over and over a given section of the audio
or video production and make lots of changes until you get it just right, never having to worry about losing
your synchronization between the audio and video signals. The machines are “locked” as if they were on
the same piece of magnetic tape, but they are not. In fact, the video may be on a VHS or Hi8 tape and the
audio may be on another VHS or Hi8 tape, or even on a cassette tape or computer hard disk. It all depends
on the type of equipment you are using.
Hard or Soft
Multi-track recorders are currently available in software or hardware, with anywhere from four to 128
tracks. Current storage mediums include magnetic tape (VHS, Hi8, cassette or open-reel) and computer
hard drives. Your multi-track system could be either analog or digital and be hardware or software based,
controlled manually or on a computer screen. Let’s work our way up the multi-track systems ladder.
Most basic are the four-track and eight-track cassette machines. The four-track machines usually
have a basic mixer built in, but not the eight-track machines. Don’t expect them to be able to sync the audio
and video with time code, but for a few dollars you can do short sections with “wild” sync. Fostex, Tascam,
Vestax, and Yamaha offer numerous models of these machines, some with MIDI sync capabilities. Expect
to pay between $200 and $700 for a four-track cassette machine, depending on features. The eight-track
units, mostly from Tascam, cost from $2000 to $9000, depending on features and the complexity of the
Reel-to-reel multi-track recorders, which were the workhorses of this domain, are now the
dinosaurs. Most manufacturers have stopped making them, so unless you plan to pick up some used
equipment, don’t waste your time trying to find one. Most open-reel recorders use one audio track for the
time code signal in order to synchronize, so you lose one track. Fostex and Tascam do still make a couple
of open-reel recorders.
Digital multi-track recorders that use magnetic tape are now the audio-for-video workhorses.
Typically boasting eight tracks and costing between $3000 and $5000, these machines record on VHS or
Hi8 tape–the same tape you may use in your camcorder. Alesis, Tascam, Fostex and Panasonic
manufacture digital multi-track machines. Alesis got this format off the ground with their ADAT machine,
the first to use S-VHS tape. Fostex and Panasonic also use S-VHS tape, but Tascam uses Hi8 tape stock. S-
VHS and Hi8 tapes are relatively inexpensive, so you can store your multi-track production on tape for
later reuse if necessary. All these machines require the use of an external audio mixer, available from many
sources including Tascam, Fostex and Mackie, to lay down the audio tracks and do the final mixdown. All
can sync to time code with optional equipment.
Today’s tape-based workhorse is beginning to see a challenger on the horizon. Hard disk multi-
track recording systems are coming on strong. There are a number of companies offering hardware-based
hard disk recording systems that function much like the tape-based digital multi-tracks. Instead of tape,
though, these machines use an internal or external computer hard drive to store the audio tracks. This
approach is more expensive due to the current cost of hard drives, but gives you the advantage of instant
access to any audio on the drive. Because this systems does not use a removable storage medium for the
audio tracks, this approach may not be for you. Current suppliers of hard disk hardware include Akai,
Vestax and E-MU Systems.
A bit more flexible are the software-based hard disk recording systems that use your personal
computer as the control system and your computer hard drive as the storage medium. You need a fast
computer, lots of memory, a big hard drive and, as usual with computers, more than a little bit of patience.
This approach is proving to be cost-effective because you don’t pay for another piece of hardware and
because fast, powerful computers are becoming more affordable. Low-cost software, like Opcode System’s
DigiTrax ($199), or OSC’s Deck II ($399), MacroMedia’s SoundEdit 16 ($379) or
Avid/DigiDesign’s Session ($199) offer many functions and features for the money. If you are now
doing video editing on your computer, why not do your audio production on it as well?
Multi-track recorders that use magnetic tape to store the audio signals appear to be headed down a
rough road, as audio/video production software for computers continues to proliferate. It is now possible to
do multi-track audio production and video editing and effects on your personal computer. Software
programs like Adobe Premiere ($795) offer you this ability with one software package. In
addition, there are many third-party plug-ins available to enhance the performance of this widely used
multimedia software package.
With the concepts, techniques and equipment detailed in this article, you should be able to start
producing more creative and exciting soundtracks. You may want to start small, with a four-track cassette
machine, to get a feel for the techniques involved. Once you get a taste of it, a simple soundtrack just won’t
do anymore, and you’ll probably want to move on to using digital multi-track machines or computer-based
hard disk multi-track systems.
The quality of your audio soundtrack is one of the real indicators of video production
professionalism. Using a multi-track audio recorder to produce your audio soundtrack represents a big step
towards producing more professional work.