The B&H Guide to Camera-Mount Wireless Microphone Systems

By Sam Mallery

Courtesy B&H Photo Video

When you need a microphone that enables you and your subject to move around without being tethered to wires or power cords, the tool you need is a battery-powered portable wireless microphone. Such a system is commonly used by videographers and by location sound professionals, or in any situation where the microphone needs to be wireless and the system cannot be plugged into an outlet for power. This article is part one in an ongoing series on the subject.

Portable wireless systems are composed of three basic components:

1) The microphone

2) The transmitter

3) The receiver

In very basic terms, the microphone attaches to the transmitter, and the transmitter beams the audio wirelessly from the microphone to the receiver. The receiver then plugs into the mic input on a video camera, or into a mixer, etc.

Microphones

There are different kinds of wireless microphones used in various situations. In "run-and-gun" situations where you may need to interview people quickly on the street, a handheld wireless system is the tool of choice. In the second part of this series, we'll discuss the benefits of using a plug-in transmitter system with a handheld interview microphone.

The tiny microphones that often get clipped a subject's clothing are called "lavalier microphones." Lavaliers are very popular because they are so inconspicuous. Wireless lavalier microphones are comprised of an ultra-compact microphone and clip with a thin wire running from it. The thin wire ends in a connector jack. The connector jack plugs into what's called a "bodypack transmitter." For more information about lavalier microphones, check out this Pro Audio Update article.

Transmitters

Bodypack transmitters are often clipped to a subject's belt, or put into a pocket. When a lavalier microphone is being used, the wire from the lavalier will plug into the bodypack transmitter, and the mic will be clipped to the subject's clothing. In addition to microphones, some transmitters can also be adjusted to accept a line level signal from devices such as mixing boards.

Helpful Hint!

A wireless system will perform better if the antenna of the transmitter isn't totally obscured and hidden under clothing. These systems tend to work best when the antenna of the transmitter and the antenna of the receiver are within eyeshot of one another. It's also important to note that different kinds of transmitters have different kinds of microphone input jacks on them. If you would like to try a different lavalier or headset microphone with a bodypack transmitter, we recommend consulting one of our pro audio experts at 1-800-416-5090 to find a compatible product.

Receivers

Portable wireless receivers generally have one or two antennas, and they often come with accessories that allow you to mount them to a video camera.

There are essentially two kinds of wireless receivers: Diversity and Non-Diversity. Diversity means that the receiver has switching mechanisms inside of it that help prevent drop-outs and interference. A Non-Diversity receiver does not have these mechanisms.

	People are often surprised to learn that it is not possible to use more than one wireless microphone with a single receiver. This is only possible when you're using a portable receiver that is designed to receive two signals, which are called Dual Channel Systems. The receivers in these systems have two receivers built into a single chassis.

UHF or VHF?

One distinction that really affects the quality and price of a wireless system is whether or not it uses the VHF or the UHF frequency spectrum. This can get confusing very quickly, namely because VHF stands for Very High Frequency and UHF stands for Ultra High Frequency. What's the difference between Very and Ultra? Well, Ultra high frequencies are higher than very high frequencies. The benefit of higher frequencies is that there is less congestion. There is less traffic for your signal to compete with. We always recommend UHF over VHF. UHF is more reliable, and reliability is everything. When you use a VHF system you are sharing the airwaves with police, fire, and taxi radio dispatchers, cordless phones, etc. It can get crowded.

Frequency-Agile or Fixed-Frequency?

We just described how Diversity and UHF systems help you avoid interference, but no wireless system is impervious to it. Wireless systems are either "frequency-agile" or "fixed-frequency." Frequency-agile means that you can change the frequency that the transmitter and receiver operate on. This is useful if you're experiencing interference. With a Frequency-Agile system you change and match the frequency settings on both the transmitter and receiver in order to find a clean channel to use. Some systems have scanners that can help you locate a clean channel. Fixed-Frequency systems have only a single channel, so if you're getting interference, there is no way to remedy the situation.

What am I paying for?

The price range for these wireless microphone systems can vary from $100 to over $3000 for a single system. There are many factors that can make one model more expensive than another: better audio quality, higher quality components, Diversity, a strong signal strength. The main factor that will drive someone to spend more money on a portable wireless system is reliability.

Imagine you're a wedding videographer and your wireless microphone system experiences static interference or drop-outs during the exchange of vows in the ceremony. Chances are you're going to have a pretty unhappy client. Numerous factors could lead a portable wireless system to experience interference: radio or television broadcasts, cordless devices, even materials like glass can disrupt your signal. Everyday the airwaves get more and more crowded with new handheld gadgets and high-definition broadcasting. Professionals whose livelihoods depend on the reliability of their gear usually opt for a more robust portable wireless system.

Some of the popular wireless UHF lavalier systems sold here at B&H

Let's review what we learned in this article

Portable wireless systems can come with three different types of transmitters:

1) Plug-in transmitters

2) Handheld microphones with built-in transmitters

3) Bodypack transmitters for lavalier microphones

There are two kinds of wireless receivers:

1) Diversity (has switching mechanisms that help to avoid drop-outs)

2) Non-Diversity (does not have these mechanisms)

The difference between UHF and VHF is:

UHF transmits on higher frequencies with less radio traffic

VHF is less expensive but more prone to interference and drop-outs

Wireless systems are either Frequency-Agile or Fixed-Frequency Frequency-Agile = you can change the frequency on the transmitter and the receiver Fixed-Frequency = the frequency of the system is fixed and cannot be changed

Thanks for reading this Pro Audio Update article, the first in a series of articles on the topic of Camera-Mountable Wireless Microphone Systems. In the second part of this series we will discuss the virtues of plug-in transmitters and go over options for mounting single and multiple receivers to a video camera.

How to Capture and Produce Great Sound for Video

How to fine tune and use your wireless microphone system so that you can get the best possible audio when you are shooting video