Sound Advice: Stereo Recording Techniques

Hal Robertson
November 2001

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Today's camcorders are marvelous devices. They allow us to relive events of the past with vivid color and "you-are-there" picture quality. Unfortunately, the audio we record with our camcorders often pales in comparison. Usually noisy, distant and unfocused, typical camcorder audio leaves quite a bit to be desired. But it doesn't have to be that way. With some planning (and a little extra equipment), the audio on your video recordings can rival that of mega-buck productions -- with a broad stereo soundscape you'll be proud to play on any home theater system.

Is stereo audio worth all the extra effort? In many cases, yes. In this article, we will explore several of the most popular techniques for recording stereo audio and how you can apply them to your next video shoot.

Before we start talking about microphone patterns, distance measurements and the like, lets take a quick look at what you'll need to record stereo audio. First, forget the "stereo" microphone built into your camcorder. Yes, you might put it into service in an emergency, but your recording will include noise from the tape drive, zoom motor and focus mechanism. It will also pick up any noises you make, including your breathing and hands. Simply put, you need external microphones.

There are several hardware items to acquire as well: a tall (10-15 feet) microphone stand, mounting hardware and long microphone cables are necessities. Depending on your microphone choice, you may also need an audio mixer to combine and power the microphones. Of course, a good pair of headphones and a 50-foot power cord will come in handy too.

Finally, you have to decide where you will record the audio: direct to the camcorder, to a master video recorder, or to another audio recording device (MiniDisc, CD recorder, etc.). This decision affects both your hookup for the recording and your options during post production. Recording to the camcorder is the most direct method, but will require some special adapters. Using a master video deck means that you won't actually record any audio in your video camera, but is simpler to set up. A separate audio recorder is the most complicated method, since you will have to recombine the audio and video elements later, most likely in a computer. Just make sure you are completely prepared for whatever technique you choose.

There are several methods for recording stereo audio. Some are very simple while others require hours of setup time and a crew to keep everything straight. Let's focus on a handful of the most popular techniques -- those requiring a minimum of equipment and producing maximum results.

Also called A-B Stereo, this technique uses a matched pair of omnidirectional microphones positioned 40 to 60cm apart on a very tall mike stand or suspended above the recording subject . This stereo technique is well suited to large concert events -- choirs, bands and orchestras -- where you set the mike stand several feet behind the conductor and position the microphones 10 to 15 feet in the air. Of course, several real-world factors will determine your actual microphone position: size and liveliness of the room, depth of the stage and loudness of the recording subject. As a general rule, the further back you position the mike stand, the more ambient the recording becomes - picking up more of the room and less of the subject.

There are strong benefits to this technique. Spaced omnis usually produce a large, spacious soundfield with excellent detail. Low frequencies are faithfully reproduced and the recording will have a very natural sound. If there is an audience at the performance, its applause will be just as clear and detailed as the music. On the other hand, the spaced omni technique can sound very different when played back over a typical mono Television speaker. That leads us to the next technique:

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