Wireless microphone

A wireless microphone is a transmitter — a handheld body, or a bodypack feeding a lavalier or headset — paired with a receiver at the audio rack. Freedom of movement is the obvious benefit. The constraint is that it is a radio service, operating on shared, secondary spectrum, with rules that have tightened considerably.

The usable ground in the United States is now mostly the UHF television band from 470 to 608 MHz, shared with whatever broadcasters are on air locally. The 600 MHz band that a great deal of older equipment was built for was auctioned to mobile carriers, and microphones were required to stop using it by 13 July 2020. Equipment tuned there cannot legally be operated or sold here, which is why a sound company’s inventory age is a real question rather than a pedantic one.

Two narrow slices survive either side of that auctioned band and are useful in a crowded market, at reduced power. There are also systems working at 900 MHz, 1.9 GHz and 2.4 GHz, which avoid the television bands entirely and bring their own trade-offs in range and congestion.

None of this is a reason to avoid wireless. It is a reason the channel plan is produced by somebody who scans the actual site, and the reason a show with many channels books the coordination as work rather than assuming it.

Corporate event production — owned inventory, our own crew, and a site survey before anything is specified.

• Frequency coordination Choosing an operating frequency for every wireless device on site so that none of them, in combination, lands on top of another — the work that decides whether the microphones hold.
• Lavalier microphone The small clip-on microphone worn on a lapel — invisible on camera, and the one whose sound is decided almost entirely by where it is placed.
• In-ear monitors (IEM) A personal monitor mix sent to a performer’s earpieces by radio — quieter stage, better mix, and one more set of frequencies that has to be coordinated alongside the microphones.