Wireless microphones have become incredibly common in recent years—from concerts, to talk shows, to spin class—but do we ever stop to think about how they work?
What’s the Difference Between Wireless and Cable Mics?
Microphones with cables seem like a simple concept to most people. They take sound and convert it into an electrical audio signal, and it is sent through a cable to a mixer or sound system. Wireless microphones, however, send sound through thin air. They do this by converting the sound into radio-frequency (RF) energy and sending it from the microphone’s transmitter to the microphone’s receiver, which then converts the signal back into audio and routes it into a mixer. So technically, a wireless microphone (with a transmitter) is a small radio station, and the receiver is a radio that can be tuned to the specific frequency that matches the transmitter.
Transmitters
Ever see someone using a small wireless mic (such as a lapel mic) and notice the small box clipped to their belt or in their back pocket? That is a transmitter. Keep in mind that all wireless microphones require transmitters to send the signal to the receiver. So while the handheld mics have their transmitter built right into them, smaller microphones such as lapel mics that clip onto clothing or a Countryman that hangs on the ear, have their transmitter in the form of small boxes with antennas.
Receivers
The opposite of a transmitter is a receiver. Their function is to receive a radio signal from a transmitter and convert it into audio that you can hear from a sound system. Depending on how many microphones you are using, you can use single or multi-channel receivers, instead of having to get a separate unit for each microphone. Often, you can get a multi-channel receiver with either dual or quad capabilities.
Wireless Microphone Benefits
As we’ve covered in our blog post, “Four Types of Wireless Microphones,” there are multiple benefits to going wireless. The most significant advantage is the mobility that is gained. Performers, interviewers, and speakers are given the freedom to move around naturally, which can make both the person using the microphone, as well as the audience, more comfortable. If using a lapel mic, Countryman, or fitness headset the audio quality can be far superior as well, as it will remain equidistant from the speaker’s mouth regardless of their movement. Audio drop-offs and feedback can be reduced when using these forms of wireless microphones.
Frequently Asked Questions
What frequency range do wireless microphones use? Most professional wireless systems for events operate in the UHF band, typically between 470 and 900 MHz. The exact legal range depends on FCC regulations and varies by location. Your AV company should handle frequency coordination for your event.
How many wireless microphones can I use at once? This depends on available spectrum in your venue’s location and how well the frequencies are coordinated. Professional systems can support dozens of simultaneous channels when properly set up. Channel AV can advise on the right number for your event.
What causes wireless microphone dropouts? The most common causes are physical obstructions blocking line-of-sight between transmitter and receiver, RF interference from other wireless systems or devices, low battery levels and poor antenna placement. A sound check before the event catches most of these issues.