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Knowledge Base:  
Wireless Microphone Basics
Last Updated: 04/01/2008

Before investing in a wireless microphone system, it is important to take the time to familiarize yourself with the parts involved and some of their common features. This article is designed to help you select the wireless system that's right for you, and to provide a basic understanding of wireless systems for troubleshooting purposes.

A wireless microphone system is comprised of three main parts: a microphone, a transmitter and a receiver. In the case of hand held microphones, the transmitter is built into the microphone, but for the purposes of this article we will be considering systems with headset microphones.

The microphone (AKA headset) has five parts worth noting: a capsule, a boom arm, a headband, a cable and a connector. The capsule is the part of the microphone that converts sound energy (your voice) into an electrical signal that a wireless transmitter can broadcast. This is the most important part of the microphone by far, and also the most delicate. Blowing on or yelling into the capsule can cause it to fail. Because your breath contains moisture you should position the capsule to the side of your mouth, rather than in front, in order to prevent corrosion (rust). Depending on the microphone, it is also recommended that you use a windscreen. The boom arm is the piece between the capsule and the headband. High quality microphones with sensitive capsules have rigid boom arms to prevent you from moving the capsule too close to your mouth. Microphones with less sensitive capsules usually have flexible boom arms to help you position the capsule for better sound quality. The headband helps keep the microphone in place on your head. Some are designed to be worn over the top of your head, but most are designed to be worn around the back of your neck. Generally the cable isn't of great importance. Microphones designed for fitness, however, use stainless steel wires in order to help resist corrosion. General purpose headset microphones use copper wires and are more susceptible to rust. The connector is the piece at the end of the microphone cable that attaches the microphone to the transmitter. There are several common connectors used in professional wireless microphone systems, and different manufacturers wire their connectors up differently.

The transmitter (AKA body pack, AKA battery pack) takes the electrical signal created by the microphone and transmits it via radio frequencies to the receiver. Older transmitters broadcast in the VHF (Very High Frequency) band, while newer transmitters generally broadcast in the UHF (Ultra High Frequency) band. Both VHF and UHF systems are commonly used. UHF systems offer greater range and clearer signal while VHF systems consume less power, meaning longer battery life. Transmitters generally have few user accessible functions. All transmitters have a power switch. Some transmitters also have a Mute switch, some have a Mute option in the power switch (On/Mute/Off), but most have no Mute feature. Inside the battery compartment of the transmitter, or occasionally on the side, are volume controls called Trim Pots. These knobs are used to adjust how loud the microphone is. Some transmitter product lines have a guitar version as well, so you may have two trim pots. They are usually labeled MT and GT. As a general rule of thumb it is best to turn the GT knob all the way down (counter-clockwise) and to set the MT at a low to medium level. Multi-channel UHF systems will also have a method of selecting which channel you would like to use. On many wireless systems this is a knob located near the trim pots. Single channel wireless systems operate at a fixed frequency. If you are planning to purchase a spare or replacement transmitter, be sure to find out what frequency your system is operating on!

The receiver converts the radio signal being broadcast by the transmitter into an audio signal that can then be connected to a mixer. Most receivers have a power switch, a volume knob, one or two antennas and a power supply. Some receivers have signal and level meters to indicate the strength of the wireless signal and the volume of the audio signal being transmitted. On basic wireless systems, there may only be a single indicator light. These indicators are usually labeled RF (Radio Frequency) and AF (Audio Frequency) and are very useful in troubleshooting. Many receivers also have a squelch control. Squelch is a function that turns off the audio output of the receiver if the signal strength is too low. This helps to prevent noise and static from being amplified by your sound system. Squelch controls should generally be set fairly low (or even off) to prevent them from cutting off the audio too soon. You should only use a higher squelch setting in situations where there is noticeable background noise or hiss coming from the wireless system. The receiver will also have an output of some sort. It may have line level (1/4" connector, balanced or unbalanced), mic level (XLR connector, balanced) or both.

These descriptions are generalizations. Some wireless systems have features not described above and some lack certain features described above. For more information on wireless microphone systems for use in the fitness industry, please contact us. We can help you determine if your current sound system will allow you to use a wireless microphone, explain proper care and maintenance for your wireless microphone system and assist in set-up or troubleshooting of your wireless microphone.

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