The musical was going smoothly, and as the chorus rushed off stage the star began to sing her love ballad. As the orchestra finished the introductory notes, her mouth opened. But instead of a lyrical soprano voice pledging her undying love to her beau, a metallic male voice intoned “Base to Car 7. Car 7- I got a fare for you. Pick up a lady at the bus depot.” The look on her face was a combination of shock and anger, and the stage manager began to panic since the sound system seemed to have ghosts! Does this ring any bells with sound technicians and roadies- it’s the wonderful world of wireless microphones.

Radio communications equipment has come a long way in the past twenty years, and the older analog receiver has been replaced with digital technology. The microphone packs and base stations have gotten smaller, and more channels have become available for entertainment use. But we still have a major problem: There are only so many frequencies in the spectrum, and they are shared by many applications simultaneously. All that you have to do is monitor the UHF radio band with a police scanner, and before long you will be eavesdropping on a neighbor’s baby monitor or cordless telephone conversation. Many homeowners have received a surprise when their radio-controlled garage door opens while their car is still inside, or your favorite fishing spot is suddenly crowded with fellow boaters who tuned in on your ‘private’ conversation with your buddy on the marine band.

Thus, the first advice that I offer to a technician who is planning to use wireless microphones in a show: find out what frequencies will be used by your system. Then, check with the local two-way radio shop or a ham radio enthusiast to see who else may be lurking nearby on the same channels. For example, many newer wireless transmitters operate on the 720 Megahertz band. When it was first authorized by the FCC (Your taxes at work support this agency, sometimes known as the frequency gods.) there was nobody else sending signals out in that portion of the spectrum. However, within the past five years there has been a move to convert the local television stations to a new format called DTV. (No, not Disney TV but Digital TV!) Guess what channels were assigned to this latest fad? Yup-the very same 720 Megahertz band that is currently used by entertainers. So you may power up your microphone system some night and instead of a rocking vocal solo the audience may hear a commercial for Burger King!

Next, remember to always check the batteries in each belt pack. Again, technology marches forward. The dime store AA battery has been replaced by a Dilithium Crystal(Oh no-that’s Star Trek-sorry I meant Nickel Cadmium!) rechargeable battery. The best charging rack will not help if the battery loses the ‘juice’ in the middle of the show. Make sure that the batteries do not develop a memory where they are charged, used, and placed back in the home unit for the same amount of time each night. In addition, purchase spare rechargeable batteries and rotate them between your packs. As an emergency measure, it wouldn’t hurt to have a package of store-bought disposable AA, AAA and 9 volt batteries in case of a power failure. One more note-check the copper battery contacts or pins in each belt pack to prevent oxidation or loss of voltage caused by a loose connection.

How does the radio signal get pulled from the air and end up in the sound system? The antenna serves this important function. Did anyone ever lose their Cable TV connection, and end up having to field engineer an antenna with a coat hanger, aluminum foil and some gaff tape? Then you had to move the contraption around to get the best signal and eliminate those gray patches around the picture? Wireless microphone receivers need the same loving care, as you can’t simply take the ‘rubber ducky’ antenna out of the box, attach it to the base station and instantly obtain great reception. (Unless you are within ten feet of the performer, in which case the signal is so strong that you could substitute a short piece of bell wire as the antenna!) The better wireless systems feature a diversity receiver, which has two channels running at the same time and only the stronger signal is chosen. You can identify these units by the ‘co-phased’ dual antennas in the rear. (They look like the old TV Rabbit Ears that were popular in the 1960’s.) If you are only using one antenna, there are still a few tricks to gain better reception. One, move the antenna away from your sound system and elevate it. You can run up to fifty feet of coaxial cable and not lose any signal. (Your audio dealer will stock this accessory kit.) You can also try a special antenna called a Yagi (not the bear-he was a Yogi!) that is a directional device much like the older TV antennas that were mounted on a rooftop pole. It can be pointed directly at the location of the performer on stage.

Microphone placement and the location of the belt pack is the last item to discuss. Today’s Broadway shows hide the mike under a wig, in the lady’s undergarment, clipped to a sword or rifle belt and maybe in a hollow tooth for all we know. The sound technician must be aware of the audio levels from each performer, and the movement on stage. There is nothing more embarrassing than the cracks, pops and hiss that can result if a radio signal is lost and the receiver remains live. The belt pack usually has a small ‘mouse tail’ antenna that trails below the unit, and if that piece of wire gets caught in a costume or moves out of range behind a set piece there can be a reduction in reception. Map out the stage before you complete the audio installation, and surprise interruptions will be reduced. Make sure that the costume person, roadie, or personal assistant treats the belt pack with care, and it does not end up casually tossed into a makeup tray or ice bucket.

This article just covers the basic ideas about coaxing the best performance from your wireless audio system. There are many specific ideas that manufacturers like Shure and Vega can provide via their websites. And, as mentioned earlier, your audio supplier works with the equipment every day and pages of helpful advice are available from the rental shop guy. The single most important advice that this author can offer is to thoroughly test the radio units at the location where they will be utilized. In that way, you can bypass the need to entertain the audience with gossip from the local taxi dispatcher, and assure that your music is coming through loud and clear.

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