This is archive material from Jay's popular Audio Solutions column in DV Magazine.
Most of this content is still valid and useful... but some of the specific information may have changed. You'll find newer, more comprehensive, better written tutorials in my books. The blatant ads on the right take you to downloadable samples, critical comments, and discount sales.
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Got to Lav it!
by Jay Rose Published January, 2000
What's been around a long time, is popular on stage and screen, and doesn't get any respect? We're not talking Rodney Dangerfield...I used to keep an RCA 77DX mic in my studio, because of its wonderfully mellow sound. This is the giant jellybean-shaped mic on David Letterman's desk, that instantly says "microphone" to anyone who sees it. But everything is shrinking these days, and mics are no exception. Letterman is really being using a tiny lav, because it sounds better in his application. That classic RCA 77 -- one of the all-time great mics -- is there just as a visual prop.
Lavs work because they can be closer to a performer's mouth than any other kind of mic, so they hear proportionately more of the voice and less room noise than a boom or camera mic. While those larger mics tend to be directional and most lavs aren't, proximity is the more important factor. (Besides, even the most directional microphones are less directional than you'd think: see the March, 1999, Audio Solutions )
In fact, a lav's sound is often considered too tight for dramatic dialog. But if a video spokesperson is talking directly to the viewer, their intimacy can be perfectly appropriate. In fact, I usually ask for a lav track on dramatic scenes, just as a backup in case the boom track gets noisy. When they're recorded right, you can cut between boom and lav on a syllable-by-syllable basis with just a little eq and digital reverb to smooth out the difference.
Lavs are also fairly cheap to use, which makes them even more attractive to the video producer: a good miniature mic costs about a third as much as an equivalent-quality boom mic, and doesn't require a skilled operator at the shoot. But -- like everything we cover in this column -- there are a few tricks to using them right.
The first lavalieres, in the early days of television, were so big and heavy they had to be worn on a lanyard. In fact, their name came from Louise de La Vallière, a girlfriend of Louis XIV, who liked to suspend pendants from a gold chain around her neck
Today, lavs use tiny electret elements and can range in size from about 3/8-inch diameter, to smaller than the head of a match. The smallest ones can be virtually invisible, even when they're on-camera.
Figure 1. A little mic that isn't there. The Countryman B6 is so small, it disappears on camera.
Figure 1 shows a Countryman B6 lav on my collar... well, actually it doesn't, unless you examine the inset. Close-up, the B6 looks like a drop of glue on the end of its wire. It can be poked through a buttonhole or loosely-woven sweater and secured with tape on the back and completely disappear.
A mic that small can be electrically noisy, but designs have gotten smarter as well as smaller, and the Countryman sounds about the same as my standard-size Sony ECM-55Bs (shown in Figure 2).
Almost all lavs are omnidirectional, but their actual pickup is one-sided if the actor's body is in the way. There are also a few directional lavs available, but they're best as planted set mics. It's almost impossible to mount a directional lav properly on an actor.
There's often no need to hide a lav if the talent is obviously talking to camera (Letterman's mic is in plain view). It's always easier, and always sounds better, to clip the mic outside the clothing. But a surface-mounted lav can still be relatively invisible: Try wrapping paper tape around the mic and clip, and coloring it to match wardrobe. Some of the smaller mics come pre-colored, or with plastic caps, to match skin tones and clothing. If the colors are close, television's natural blur will make the mic disappear in all but the tightest shots.
A lav should be as close to the mouth as possible. A shirt collar or high up on a lapel is always preferable to the middle of a necktie. If talent's head will be turning during the shot, choose the favored side -- usually the side facing the interviewer or camera.
Figure 2: Run the cable up into the clip (A)... then, inside the wardrobe, let the clip keep the cable in place (B). Don't ask what my model's hand is doing INSIDE the shirt.
Don't let a lav's cable dangle. Mechanical noises, including clothing scratches, can be transmitted up the cable and mix with the voice. Some pro mics use special Kevlar-based wires to reduce noise and add strength, but you still have to provide a strain relief. If you're using a clip, loop the wire up through it and into the clothing (Figure 2a). Then grab it with the clip's teeth (Figure 2b) to hold the loop in place. If you're using a tie-tack mount, make a loop of wire and put some tape on each side.
You can guarantee a mic will be invisible by hiding it inside the wardrobe... again, as close to the mouth as possible. The sound will be muffled, but that can be helped by using a mic with a high-end boost or by equalizing in post.
There's a bigger problem with clothing mics: when wardrobe rubs against them, the rustling noise is impossible to remove. The best cure is to provide a relatively solid mounting. Take a couple of pieces of one-inch tape and fold them, like a flag, into triangles that are sticky on both sides. Place one triangle inside the outer layer of clothing, and stick the mic onto it (being careful not to cover the holes where sound comes in). Then press another triangle onto the mic, and stick it to the next layer of clothing. If the talent is wearing a blouse and the next layer is skin, use anti-allergy surgical tape... and wipe the skin with alcohol first to remove grease and perspiration. Tape a small loop of cable a few inches below the mic as a strain relief.
If you still hear wardrobe rustling, try softening the cloth with anti-static spray. Or if the clothing is heavily starched, spray water on it near the mic for some local de-starching.
Mics can also be hidden outside the clothing. One favorite trick is to cut open a pen, place the mic inside, and stick it in a shirt pocket. You'll have to make a small hole for the wire, but presumably your video has some budget to repair wardrobe. Very small mics can be taped to the skin under long hair, or even mounted to an eyeglass frame for long shots.
GET PLUGGED IN
Lavs -- like other condenser mics -- require power. There's usually a battery built into their XLR connector, or they can be powered from the mixer. Current drain is low, so the battery is good for at least a day's shooting. Most lavs are also available to use with wireless transmitters, and are powered by the transmitter's battery. Of course, wireless batteries are good for only a couple of hours.
A wired connection is more reliable, so cable is usually run out the back of a jacket or down a pants leg. But don't let the XLR connector dangle! This puts extra strain on the thin cable, and the connector can rattle when the character moves. Instead, use a safety pin to attach the connector to the clothing -- or an Ace bandage or ankle warmer to hold it to the leg -- and run an extension cable to the mixer or camera. Between takes, the talent can unplug and roam around.
Jay Rose (firstname.lastname@example.org) is an Emmy- and Clio-winning sound designer. Visit his studio at www.JayRose.com.