Selecting a Microphone:
A majority of the production dialogue recorded in major "Hollywood" theatrical productions and television series is miked from overhead, utilizing either a fishpole or studio boom.
Overhead miking provides a natural sound. Normal sound effects and some background ambiance are also picked up, and at lower relative level than the dialogue, thus rounding out the total track.
Perspective matches camera angles, since the boom mic is able to get in closer on tight shots, and is further away on longer angles.
In contrast, the use of lavalieres and radio mics produces dialogue that is often sterile in texture – lacking natural sound effects and ambiance. Perspective is always forced and "close-up" – regardless of camera angle. Audio is often subject to abrupt changes in presence, such as those caused by talent turning their head off-axis to the lav, or leaning over a hard surface (such as a desk or podium). Last, though surely no least, lavalieres are prone to distracting clothing noise and other interference.
A good technique is to follow the same approach towards dialogue recording as practiced by feature mixers: Use lavalieres with discretion and take advantage of overhead miking as much as possible.
Microphone selection plays an important role in overhead miking technique, along with choosing a skilled and experienced boom operator. Just like camera lens focal length, there is no one choice of specific microphone that will be right for all situations A professional package should include an assortment.
It cannot be over stressed that, for best results, only the highest quality condenser microphones – such as those discussed in this section – should be used in capturing dialogue. Although most electret condensers are very good microphones for their price and features, they simply do not perform as well as condensers for professional or theatrical dialogue applications. Top of the line condensers offer superior reach and sensitivity over the electrets, and that can spell out the difference on those more demanding shots between getting ‘rich’ dialogue versus ‘weak’ or ‘thin’ audio.
Allow the extra room in the budget to purchase or rent a package of true condenser microphones along with the proper accessories (power supplies, shockmounts, blimp windscreens) to make them work.
Similar to telephoto lenses, shotgun microphones tend to compress the distance between foreground and background. Avoid pointing the mic as if it were a rifle, unless you are totally unconcerned about bringing up the background. Be careful of what is I the "line of sight’ behind the talent.
The best way to eliminate this "telephoto" effect is to aim the mic down from above, so that the only "background" in the microphone line of sight is the silent ground.
The most popular microphones for exterior use are long shotgun microphones. Long shotguns offer narrow pick-up patterns and excellent sensitivity and reach. Deployed overhead of talent, tilted just slightly towards the mouth – these mics will eliminate considerable background ambiance while still picking up natural sound effects such as footsteps and hand business. Because of their directionality, these long shotguns can be played at greater headroom above the actor when necessary (up to several feet depending on ambient noise), thus facilitating the wider frames more common on exterior set-ups.
The disadvantages of the long shotgun are its directionality and physical dimensions. The narrow pick-up pattern requires that much more care be taken in cueing (aiming). Moving talent must be meticulously followed; multiple talent requires rapid and precise repositioning of the mic for each person’s lines. The physical length sometimes becomes a problem, for example, in interiors with low ceilings.
The extended length of the shotgun is usually not a problem when working outdoors, although situations may arise where a shorter mic is necessary. Weight, on the other hand, can be a definite problem Do not underestimate the strength required to manually support a fully extended fishpole complete with shotgun mic, shockmounts, and windscreen over the course of a long day!
As mentioned before, there are situations when a long shotgun may not be the microphone of choice due to size, weight, or narrow degree of pick-up.
The short shotgun is characterized by its more manageable length and wider pick-up pattern (supercardioid or hypercardioid). The somewhat wider (though still very directional) pattern makes it easier to follow, or cue the talent. On the other hand, the effective working range (maximum distance)of the mic is diminished. Also, the wider pick-up pattern tends not to isolate talent from ambient noise as well as the long shotgun.
Interior situations pose an entirely different set of problems for the sound mixer. It becomes a question of striking a balance between reach versus acoustics.
Shotgun microphones with interference tubes tend to exhibit loss of definition when used in confined, bare-walled interiors such as kitchens, bathrooms, small offices, and so on. This phenomenon is caused by reflected sound waves interfering with the acoustic noise canceling principles employed with the interference tube.
The solution is to use the wider-angle condenser mics without interference tubes. The problem is that these wider-angle mics (cardioids and hypercardioid) also have less reach. It becomes a matter of trade off between choosing the crisp sound offered by the wider pattern mics versus getting the reach needed to isolate dialogue from the background noise due to higher distance often demanded by the camera angle.
Applications and Types of Wireless Microphones
Wireless microphones can be categorized as handheld, body pack, or plug-on; VHF or UHF; and diversity or non-diversity.
Hand helds refer to the hand held microphones that have transmitters built into them. They are popular for vocalists, and variety stage performance. Body packs consist of transmitters only and can be thought of as "wireless cable" rather than "wireless mics," since any microphone (with the appropriate adapter cable) may be plugged into them. Body pack transmitters are generally used with lavaliere microphones. Wireless units can also be used with a condenser mic on a fishpole or a stationary mic planted on the set.
Wireless mics can be VHF or UHF. Most professional units share the upper VHF television bands (TV channels 7 through 13). If you expect to be shooting out of town or on the road, make sure there are no local TV stations broadcasting on the same frequency as your radio mics. For instance, manufacturers’ designated (A) "traveling" channels (169-172MHz) are popular for use in most places across the United States.
Wireless microphones are available in the UHF frequency range. The UHF frequencies, compared to VHF, are less susceptible to most common sources of radio interference. A greater number of UHF units can be operational at the same time without cross interference, a definite advantage when doing stage and variety work. Another advantage of UHF is that the transmitter antennas on the body packs are very short and do not require careful rigging to the actor’s clothing.
"Diversity" receivers work on the principal of switching between two receivers, with antennas placed at least ¼ wavelength apart. The diversity unit compares the incoming signals continuously, and instantly switches to the better signal, thus eliminating "drop outs" or dead spots.
Body Pack Application
Without question, the most difficult aspect in using radio mics is correctly attaching them to the body of the actor or actress.
Body pack transmitters can be hidden almost anywhere. The most common sites include the small of the back, rear hip, inside thigh, ankle, pants pocket, and inside chest pocket of a jacket, or in the heroine’s purse. When talent is wearing a scant bathing suit, for example, radio mics can sometimes be hidden under straw hats, or even on the back of the neck under long tresses of hair. Leg warmers provide a convenient place to hide radio mics when dealing with exercise attire.
There are a number of ways transmitters may be secured. Belt clips work fine under a jacket or loose top. Special pouches or pockets can be pinned (or permanently sewn) into wardrobe. Sometimes it is possible to merely hang the unit with a safety pin that has been tapes onto the transmitter casing. Specially constructed elastic belts known as belt and pouch kits, such as those manufactured by PSC, can be worn around the waist, thigh, calf, or ankle. Transmitters can be also held in place by elastic bandages.
Any time camera and gaffer tape is used, special care must be taken not to tape directly to skin or delicate wardrobe (such as nylon stockings). Fold the tape over itself to form a non-adhesive strip to wrap around first. Better yet, use some sort of liner, such as a strip of cloth. Avoid placing the transmitter directly against the skin; since body moisture tends to interfere with (absorb) the outgoing signal.
Care should be taken in securing the flexible transmitter antenna cable. To prevent the antenna from being torn from its connector the first time the actor moves or bends over, use a rubber band to provide elastic strain relief. Attach one end of the rubber band to the tip of the antenna. The free end of the rubber band can be safety-pinned to the clothing or taped in place (use medical tape on skin). Thus, the antenna can be maintained reasonable straight (a little bit of slack is okay) yet protected against damage.
The transmitter antenna can be run vertically up or down from the body pack. However, if the antenna trails downward, then the transmitter should be mounted in an inverted position to avoid making a loop in the Antenna. The transmitter antennas can also be run horizontally, such as partially around the waist. However, in these instance, the receiver antenna may need to be tilted sideways (matching the angle) to improve reception.
Under no circumstances should the mic line and antenna wire ever cross. This will definitely reduce your range. Run the mic cable out from the body pack in the opposite direction of the antenna. When the transmitter is mounted on the body upside down (the antenna running downward), it is okay for the mic line to loop upward, as long as it doesn’t cross the antenna. Install a fresh battery in the transmitter every time you use it. It sounds like a detail that should be obvious, but all too often, radio mic problems boil down to a weak battery in the transmitter. Change the battery frequently – every four to six hours with most brands.
Forced Perspective
There are a couple of ways to soften the problem of forced close-up perspective. The first is to select a lavaliere with an open sound, such as the PSC MiliMic, Tran TR-50 or Sennheiser MKE-2, rather than a lavaliere that tends to isolate, such as the Sony ECM-55. Another solution is to attach the lavaliere a little lower on the body than usual. When there are two people playing close to each other, it sometimes helps to mic each person off of the opposite person’s microphone.
Antenna Placement
The antenna of the receiver should initially be adjusted to match the angle of the transmitter antenna. Then experiment with changing the angle, for sometimes an unusual condition on the set may favor an odd combination of antenna angles to yield best signal.
A clean line-of-sight between receiver antenna and transmitter is important, since almost any object or body and deflect or absorb the RF signal. Mounting the receiver on a wooden ladder usually helps.
Wireless mics come equipped with one of two forms of receiver antenna: the straight wire "whip", or the shorter helical "rubber ducky". The straight "whip" will yield the best reception, although the "rubber ducky" offers more convenience in terms of mobility.
There are some special antenna systems that can be used to improve reception. Directional antenna systems can be used to reject radio interference, when the source is identified. High-gain antenna systems can significantly increase the range of most wireless mics.
Anytime the receiving antenna is separated from the receiver, care in selecting low loss cable becomes important. 50 ohm RG-58U is a standard cable, however it has significant loss especially at higher frequencies, keep the cable length as short as possible, and select lower loss cable for longer cable runs and higher frequencies.
Placement and Environment
Strive to maintain minimum distance between the transmitter and receiver. Move the receiver/antenna from shot to shot in order to achieve close and clean line-of-sight placement. Don’t’ be afraid to locate an antenna just outside of camera frame, or even to conceal it behind a prop right in the shot or set itself.
Sometimes, it maybe expedient to have the boom person or third person physically carry the entire receiver during the take in order to maintain proximity with the actors. Given the option, it is better to run long lengths of audio cable (from receiver to recorder) than to have long lengths of antenna cable (from antenna to receiver).
Virtually anything can interfere with good radio transmission and cause bursts of static. Check for metallic objects of any kind, such as jewelry, zippers, coins, and keys. If you cannot eliminate the metal, then at least reposition the antenna on the actor.
Carefully look at the path of transmission between the actor and the receiver. Pay attention to lighting or grip stands that may suddenly have appeared. A new influx of crewmembers or spectators can also block the RF signal.
Examine the location itself. Check for additional electrical lines, especially coiled feeds, which can generate magnetic fields. Dimmers and special effects equipment (especially neon) are always a problem. Motors can produce interference: Be aware of golf carts, forklifts, camera cranes, automobiles, and kitchen appliances.
Video and computer equipment can create strange fields. Be aware of Steadicams and other camera mounts relying on high intensity video or radio-controlled camera functions.