Looking to go wireless? A guide to wireless mic styles, setups and solutions
Wireless mics come in three basic styles:
Handheld: Handheld mics are designed for a single person’s use, whether for speeches or singing. This is also the mic to use when passing a mic around during a meeting or assembly, or as an audience mic in an assembly or council meeting.
Cavalier or Lapel: These little mics come with a clip that is attached to a lapel or collar and are useful when you want to hear what is being said or sung, without the user having to hold the mic.
Headset: Think Madonna or an aerobics instructor. These mics are worn on your head with the mic placed by your cheek.
Up until the 1960s microphones had a cord, which meant the speaker or performer was forced to stay within the limits of the cable.
In the 1970s wireless mic technology became more common and companies like Sennheiser and Nady started putting out single channel wireless mic systems. The radio frequencies used back then were called VHF. The problem was the VHF units were susceptible to interference from other wireless devices, and some radio frequencies interfered with other ones, causing pops and clicks (and occasional taxi transmissions) to come over the wireless mic system.
Since wireless microphone systems do not require a license to operate, it also leaves each channel wide open to interference from other devices. For example, if a church buys a wireless mic on one frequency, and six months later a house next to the church gets a wireless karaoke system on the same frequency, there’s nothing preventing the systems from interfering with each other.
In the 1990s wireless mics began using UHF, as the VHF frequency band was becoming overcrowded. The UHF frequency bands have far fewer dead spots than VHF systems, and generally have a further range than the older VHF systems did. Most importantly, though, UHF systems are also less prone to interference from other wireless mic systems, allowing for the use of more wireless mic systems in the same room, such as a church, bingo hall or theatrical event, where multiple wireless mics may be used simultaneously.
Naturally, as everyone switched from VHF to UHF mics, the frequency band also became crowded, and multichannel wireless mics were released at affordable prices. These range from six-channel to 1500 channel models, allowing users to simply switch to another channel that is interference free. Some models of wireless mics automatically scan the frequency range and set the mic and receiver to a free channel.
Diversity systems: Both UHF and VHF mics are available as ‘diversity’ systems. A diversity receiver has two complete receivers in one unit, complete with two antennas, and circuitry in the receiver senses which antenna is picking up the stronger signal from the microphone and automatically switches to that receiver. Of course, diversity systems are a bit more expensive than non-diversity systems.
Battery life: Most wireless mics will last eight to 12 hours on one battery. High-end microphones will have additional features such as a battery level indicator on the receiver, so a sound system operator can monitor the battery level at the receiver without touching the transmitter. This is handy both when the system is used for long hours, but also for systems that are rarely used.
Portable receivers: Some wireless mic systems are available as portable receivers, handy if you’re going to put the receiver on a floor somewhere to plug into an existing microphone jack, or if you are moving the system from place to place. Other receivers are rack mounted: permanently bolted into a sound rack to prevent theft. Some receivers come in half rack sizes allowing you to put two different wireless mic systems side by side in the same rack, saving space.
The basic wireless mic system is a non-diversity VHF system. Good for short range use and for budget systems, you usually can’t run more than two systems simultaneously in the same area as they will cross interfere. These systems are great for elementary schools. Systems are available with handheld, lapel and headset mics.
A step up from the basic VHF system is a 10 to 20-channel UHF diversity system. Many of the single channel systems have been discontinued over the last few years, as the technology has gone up and pricing has gone down, making 10 channel systems like this one more affordable than ever. A UHF selectable channel system allows you to change frequencies in case of interference, and the range and audio quality is generally better than with an entry level VHF wireless mic.
A higher end wireless mic system is a 1000 channel auto selecting wireless mic system, with a full color receiver display, with features such as transmitter battery life shown right on the receiver face. Some systems are digitally encoded, which means that the transmitter sends a digital code along with the mic audio to the receiver. If the receiver doesn’t receive the digital code, the receiver mutes and does not transmit the audio. This is very useful in mission critical applications such as theaters, where many wireless mics may be used simultaneously, and also to ensure privacy, as a radio scanner cannot decode the audio signal, even if it is set to the right frequency. This is very important for police and applications where audio privacy is a must.
Wireless mic dos and don’ts:
- Do maintain a line of sight between the transmitter and the wireless mic receiver antennae. While many UHF mic systems will transmit through walls, a concrete wall is an effective barrier to block the wireless mic signals, and even a sheet of drywall or a steel equipment rack can reduce the effective transmission range.
- Don’t drop the mic! Mic drops have become popular by entertainers in recent years, but in reality it’s never a good idea to physically abuse your wireless mic! A dented windscreen or cracked transmitter case will affect the sound quality and reliability of your wireless mic
- Don’t use rechargeable batteries. While some wireless mic transmitters are designed for use with rechargeable batteries, a rechargeable battery does not put out the same voltage as a standard alkaline battery, which can reduce range, cause dropouts, or cause short battery life before having to recharge them again.
- Don’t go cheap and use ‘no name’ dollar store batteries. These batteries often last only an hour or two in a wireless mic transmitter. Always use a name brand alkaline battery for longest battery life.
- If you use wireless mics on a regular basis, get a battery tester. An inexpensive battery tester with a ‘good/bad’ meter on it will give you a good indication of battery life left, and allow you to get the most life from a disposable battery.
- If your wireless mic receiver is mounted in a metal sound system rack, make sure the antennae are brought to the front of the rack rather than be buried in the back. This will ensure the signal isn’t blocked. Antenna extenders are inexpensive, and will increase the range of your wireless mic.
Sound Solutions carries the Audio Technica, TOA, and Mipro wireless mic lines. Call us and let us help you select the right wireless mic system for your application and budget. Sound Solutions is also one of the very few companies in Canada that owns all of the equipment needed to service today’s wireless mics, including an RF spectrum analyzer.