Getting the Best From Lavalier Microphones, January 1998EXPERTS SHARE THEIR TIPS 5/17/2004 8:00 AM Eastern
Experts Share Their Tips
lav·a·liere, n. an ornamental, usually jeweled, pendant on a small chain, worn by women about the neck. Named after the Duchesse de La Valliere (1644-1710), mistress of Louis XIV of France.
The lavalier (or lavaliere) mic is a special-purpose device, not unlike a shotgun mic or hydrophone. And like those devices, the “lav” has some sonic characteristics that restrict its usefulness. However, though the lavalier mic is rarely a first-choice mic for music recording, there are many situations in which the advantages of small size outweigh sound quality considerations. For example, though a well-positioned overhead microphone is usually the ideal location sound recording tool, when the mic must be invisible to the camera, a lav may be the only choice. Similarly, a well-positioned rostrum mic will usually sound better on an “industrial” presenter or motivational speaker, but the reality is that a lav is almost always the production manager’s first choice.
Which is not to say that it’s always the sound mixer’s first choice. A common refrain, whether on a Broadway show or on location for a big-budget feature film, is that “lavaliers are a necessary evil.” Well, they don’t have to be. This article explains how to get the best results from lavalier mics in less-than-ideal circumstances.
When selecting a lavalier mic, most of the P.A. rules of thumb apply: Gain before feedback and a flat response are primary considerations (fortunately, these two characteristics are usually complementary). Coverage pattern is also important, though even the most hypercardioid lavs tend to be far less directional than larger-format mics.
If you are renting lavs, try to stick to one model; mismatched lavs can result in impossible situations, especially when there are several lavs and a P.A. feed in the same room. An exception to this rule is when a particular mic model accentuates an unwanted timbre or sibilance.
Accessories can make the microphone. Ask your dealer what accessories are available and buy extras—when you are on location and find that you need more mics than you have, the extra clips make it feasible to pre-rig several locations and switch mics around quickly. Plus, you can now afford to lose an accessory, which is all too easy on a busy set.
In general, stick with the manufacturer’s supplied mic clip or windscreen; a substitute “universal” clip rarely works as well as the original. Also, compromised mic-mounting solutions tend to fail in the middle of a live feed, leading to stress on the mic-to-cable connection (not to mention stress on the director-to-sound-recordist connection). A warning: Don’t temporarily store accessories in your pocket. They all seem to start at a replacement cost of $30, and if you walk off the set with a pocketful of accessories, that can take the profit out of your whole day.
POSITIONING AND SECURING
The all-round best spot to aim for in hiding a miniature mic is just above the sternum or breastbone. The resonance of the chest cavity sounds much better than when the mic is positioned at the throat area. Often, a vampire clip to hold the mic inside the shirt, touching the skin, is all you need. Layers of clothes and physical action can spoil this setup fast, but if you place the mic to favor the head turn (if there is one in the shot), this placement often does the job.
Warning! When using a metal-bodied mic next to the skin, be sure that your power source is grounded properly (especially if it’s a generator) and that all cables are wired correctly. A wet field, leather-soled shoes and a truck generator in combination with a hard-wire lav can make your star anchor do the “You’re fired!” dance.
To hide a mic in or under clothes, choose a mic with a recessed grille, rounded edges and an LF roll-off characteristic. “On collars and ties, I like to hide the lav in the tie knot,” says Pete Verrando, C.A.S., a freelance production sound mixer in Dallas for the past 12 years. “The perspective is pretty forced, but the clothing noise is really minimized. Suits make tons of clothing noise. I usually tape the tie to the shirt, as well. I wrap the lav in toupee tape before concealing it in the tie knot.”
Once the mic is hung and dressed, the next few inches of mic cable should be loosely looped into an overhand knot, then strain-relieved at the nearest belt or collar. This is the little-known 9dB knot, so called because the nature of the loop and knot allegedly reduces noise by 9 dB. Hey, it works.
Successfully positioning a lav mic often necessitates a rather intimate relationship between the sound engineer and the performer. Sometimes actors and models are asked to work in cold environments, yet are costumed as if for a heat wave. A cold-metal sound component against the back can be just the thing to trigger very unphotogenic goose bumps; so, after you battery-up your transmitters and preamps, store them in your pocket for a while.
When your job involves shoving your arm under somebody’s clothes, tact and consideration are extremely important. “I don’t get much hassle from actors when futzing with their clothes,” says Verrando. “I tell them what I’m going to do first, and then get them to help me string the wire through the clothing. It helps to kind of narrate the process as it’s happening.” This goes double for high-power CEOs. These days, most are pretty media savvy, but if you’re on their turf, watch out! Confidence and politeness in these situations are essential, and don’t forget those breath mints!
Make friends on the set or backstage. Wardrobe and hair people can help you immensely or, intentionally or not, make your life miserable. They can make useful accessories like mic belts, which can help hide a radio transmitter when a dress has no pockets. Hairdressers can help you with a good head mount that positions the mic in a hat, wig, glasses, mask or hair. A good head mount is hard to beat; the proximity can be excellent, the skull resonates nicely, breath pops are eliminated, and head turns are not a problem. Make sure you have proper strain relief, and keep the wire invisible at the neck. In the case of a dancing performer, take extra care with strain relief.
Wardrobe can also provide you with integral mounting as part of a costume and quick solutions to clothes that rustle. Everyone has an opinion on which fabrics make the most noise, but most problems seem to come from layers of different types of clothing rubbing over each other. Starched or stiff clothes tightly worn are also noisy, as is contact with the windscreen, body or cable of the microphone. A few quick passes with needle and thread can often eliminate such problems.
Nevertheless, some wardrobe choices are bad news for the sound person. Jewelry, running suits, corduroy and plastic fabrics can all cause problems and should be tested for sound in an air-conditioned trailer, rather than on the set. Better yet, convince the director that you should attend wardrobe pre-production meetings.
“The main thing about body mics is letting the [assistant director] or who-ever is in charge know that sound needs some time to wire actors,” says Verrando. “On crazy shoots, when in doubt, wire ’em and it’ll be there if you need it. But it’s good form to let all involved know what I’m doing. It also trains the crew chiefs to occasionally expect a little sound setup time.”
Every sound pro carries a comprehensive spares kit and toolbox, but you will need a few more items for lav mics. It’s extra stuff to carry, but if you hang up the production while you fabricate and perfect an improvisation, you may not be hired again.
A few thoughts about adhesives. Gaffer’s tape, toupee tape and moleskin should be chosen carefully and used wisely. Residues can fill in microphone windscreens and may gunk up the diaphragm. Never store mics with tape still on them. Camera tape and paper-based tapes are bad choices. Try waterproof adhesives like surgical tape; good, fresh gaffer’s tape is always hard to beat. Most of the rest of the kit resembles items from the hairdresser’s kit, but have the items on hand anyway.
Lavaliers require maintenance, just like any other piece of pro audio gear. In normal use, there is very little that can go wrong with a lav mic, but heavy use and wet conditions should inspire cautious preventative maintenance. Molded connectors should be visually and operationally inspected, especially after a good yank on the cord. Don’t lose your chance to identify the problem before the mic is stored with its twins. Fastener-assembled connectors are notorious for coming unscrewed, so make sure you have the right screwdrivers on set. Make sure all your fasteners are well-seated, but not too tight. Watch for corrosion build-up or dirt in the contacts.
Moisture is the enemy, sweat is the worst. Joe Pino, resident sound designer at the Tony Award-winning Alley Theatre in Houston since 1990, recommends the following for sweat-outs: “There’s nothing you can do after it happens, as far as I know. Let them dry out and see if they start working again—after a few days, Pow!, there they are like nothing ever happened.” In desperate situations, try storing the mic in a zip lock with some form of sealed desiccant. As a preventative step, Pino recommends spraying or dipping new mic windscreens in Scotch Guard and then immediately blowing the mesh out with canned air.
Windscreens are often necessary outside, but they are not “rain screens.” “Lately we’ve been leaving the windscreens off—the windscreen seems to actually wick the moisture into the capsule,” says Pino. “We still use moleskin or Elastoplast occasionally as a cover and moisture barrier, especially if the mic needs to be colored to match make-up. It really depends on the performer and the application.”
A particularly important point to consider is battery power, including electret batteries, battery-driven phantom supplies and transmitter packs. Pino recommends checking the latest Consumer Reports battery tests to see how the various manufacturers’ models stack up. Such articles usually include an informative treatise on different battery compositions. The major point to note is that as voltage goes down, the noise floor seems to rise, the output is reduced and gain before feedback is reduced. The preferred type of battery starts with a high sustaining voltage that drops off sharply, rather than gradually. Never compromise on batteries, and properly dispose of them immediately to prevent reuse. No matter how much the producer whines about budget, just remind him that cameras need light and sound needs batteries. Never accept rechargeables.
And when you’ve wired the actors and are set to record, please remember: Critical EQ decisions are often better left to post-production! The watch word is consistency. In live situations, radical EQ settings chosen to favor one voice can leave other actors’ voices too thin. Further, radical EQs will not cross-cut well against the “average” EQ setting. Make sure to record some ambient room tone while you still have everyone wired.
In order to reduce noise from handling, clothes, ambience and breath pops, a low-cut (bass roll-off) EQ is allowable. High-frequency EQ should only be added in cases where intelligibility is being lost, such as when the mic is obscured by thick clothes. Unnecessary use of HF EQ can result in too much sibilance, especially in a wireless/Nagra combination. In such situations, another mic placement or another type of mic, such as a shotgun, will often yield better results.
Properly used, lavs can provide an elegant solution to many modern sound design problems, and they can often be used in conjunction with other mics to improve overall sound quality. “I often use a lav to help clarify a line in a boomed scene,” says Verrando. “When a scene is great on the boom except for a line or two, I’ll sneak the lav in the mix to perk up those lines. A scene doesn’t have to be all boom or all lav.” Don’t be afraid to experiment, and give yourself time to use the best test equipment in your rig: your ears!
PREPPING MICS THE ALLEY WAY(courtesy of Joe Pino)
1. Power up the pack.
2. Quick vocal check (“One, two, testing”).
3. PFL in cans, work the entire length of the cable, looking for continuity faults, especially at the connector.
4. Second vocal check.
5. Repeat for next mic. Note: Once mics are turned on at the console by the engineer, they should never be turned off. If you try to save batteries by leaving them off for a late power-up, you’re courting disaster.
6. After check, which should be as late as possible (keep the batteries fresh), the mics should go straight to the performers.
7. In long shows, it’s not a bad idea to change batteries at intermission.
Pino claims that, thanks to these procedures, he has mics over seven years old that are still in fine condition!
LAVALIER TOOL KIT ESSENTIALS
• Small rolls of gaffer’s tape, toupee tape, medical/surgical tape
• Vampire clips, tie-tack clips, button-hole clips
• Extra batteries
• Foam windscreens, cheesecloth windscreens
• Velcro body-pack holders
• Zip-lock bags and a sealed desiccant package
• Battery-powered shaver (used to prevent “five o’clock shadow” noise on the collar)
• Breath mints (self-explanatory)