Introduction to Wireless Microphones

There is a saying in Hollywood that the use of wireless microphones is more of a mystic art than it is a science. In spite of all of the technological advances, achieving reliable performance from radio mics is still a best case rather than an every case scenario.

The fault lies not with the manufacturers, but with the government. Due to restrictions on power output (a mere 50 milliwatts) and frequency allocation (sharing the wavelength with television channels), professional wireless mic units are readily susceptible to dropouts and local RF interference.

What this means in plain English is that a twelve year old kid can walk into a Radio Shack and buy a walkie-talkie or CB that puts out 5 watts (5000 milliwatts), yet Uncle Sam won't trust professional soundpeople with more than 50 milliwatts!

As for the matter of RF interference, anything that has ever caused your television set to hiccup (such as overhead aircraft, vacuum cleaners, computers, passing trucks) may also interfere with your wireless mic.

Never-the-less, radio mics are definitely an important tool for Production Sound recording. They are often the only practical way to get the dialogue.

Think of them as wireless cables. There is nothing wireless about the microphone itself. The fact is, it is the cable connecting the microphone to the mixer or recorder that is wireless. The microphone remains wired to the transmitter.

You may think that I am indulging in a silly game of semantics, but this is an important concept to understand. The lavalier mic is not the wireless part of the system; the XLR mic cable is what the transmitter/receiver is replacing. Virtually ANY mic, including boompole mounted shotguns, can be used with a wireless system providing that you have the appropriate adapter cable or connector.

Another concept that is important is that because wireless mics (of any brand) are always a bit of a gamble, you should hedge your bet by only deploying wireless when you absolutely have no alternate solution. Avoid reaching for your wireless as a first resort. Using radio mics is sort of like going to the dentist: it is not a fun experience but we all do it when we have to.

Exhaust all of the "hardwire" ways of miking a shot. If you can't boom it from overhead, maybe you can mic it from below. Perhaps a strategically placed "plant" or fixed mic can be rigged outside the frame or hidden within the set. If you do need to resort to a body worn lavalier, it might be possible to trail a mic line from talent's ankle.

Some scenes can be started on a wireless for the master shot, and then switched to boom mics or hardwired lavaliers for the closer angles.

Next we will look at Budget Factors.