Sound Track: A Perfect Connection (page 2)

Unless you're producing videos with full surround-sound audio, you'll be dealing with just two signal types: stereo and mono. Mono is the simpler of the two, consisting of a single audio signal carried on one cable. Even if it's coming out of multiple speakers, mono audio seems to come from just one point in front of the listener.

Stereo audio uses two signals, two wires, two amplifiers and two speakers to place sounds across a "soundstage." Sounds can then seem to emanate from either speaker, or anywhere between the two. Almost like the difference between binoculars and a telescope, stereo audio gives sound "width." You'll find most stereo signals on a pair of RCA cables. Stereo camcorder microphones will often use a stereo minijack, much like that found on portable stereo headphones.

Connecting like equipment (stereo or mono) together is a piece of cake. But what about when you need to convert from one to the other? No problem, provided you remember a few simple guidelines. Let's start with a look into attaching a stereo source to a mono input.

If you have a stereo camcorder and a mono VCR or editing system, you've probably faced this situation before. First off, resist the instinct to combine the left and right stereo outputs with a splitter. Splitters, or "Y" cables, are for making two sources out of one, and not the other way around. When you patch the left and right outputs of your equipment through a Y cable, you're wiring these two circuits directly together. While this may not seem to pose any problems, it can cause harm to certain pieces of gear.

Your best bet is to use just one of the stereo outputs, leaving the other unused. Which one should you use? Convention dictates using the left, but there are times this isn't the best choice. Say you shot a lecture or concert from near the right side of the stage. Your stereo camcorder's right mike picked up clean audio from the loudspeaker located to your right. The left mike picked up more audience noise and room ambiance. If clarity and audibility are your goal, use the right signal.

It is possible to combine the left and right signals into a mono signal, but you should always try to do this with an audio mixer. This will electrically "buffer" the left and right outputs so they're not feeding directly into each other.

Recording a mono signal on a stereo VCR or camcorder presents less of a challenge. With a Y cable, you can record the same mono signal on both left and right tracks. On playback, the end result will be mono sound that seems to be coming from directly between the two speakers. You can also record the mono signal onto just one of the two stereo inputs (usually the left).

By now, you should have a better idea how to connect your audio and video equipment for best results. Here are a few parting tips to help ensure your connections continue to pass pristine, unpolluted audio:

• When disconnecting a cable, always pull by the connector itself. Pulling directly on the cable to detach it will eventually ruin the cable, guaranteed.
• If you have to convert from one connector type to another, use as few adapters as possible. Each adapter you add increases the odds of a flaky connection. If you're handy with a soldering iron, make a custom cable to replace your most-frequently used adapters.
• Don't bother with fancy, hi-fidelity cables bearing gold connectors and designer price tags. They may offer a minuscule improvement, but only on a test scope. The real-world performance of these cables rarely justifies the added cost. At the same time,
• Avoid flimsy, thin cables that look like they'll break the first chance they get. Stick with good-quality, sturdy-looking cables. Audio cables the size of angel-hair pasta don't hold up to repeated use.
• If you're trying to interface with an existing sound system while on a shoot, don't assume you know what a cable is carrying just because you recognize the connector. Though we have some established guidelines for connector usage, no real rules apply. Try to trace any cable you plan to use back to its source. Make sure the signal type and strength are correct before you plug it into your equipment. (For a more complete discussion on cables, connectors and signal types, see "Cables and Connectors: Handle with Care" in the September, 1996 issue of Videomaker.)

So when it comes to audio connections for video, you don't have call a plumber. Just follow the directions listed above and your signals should flow smoothly from source to destination.

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