Wireless microphones are being used more and more in church sound installations during the last 25 years. As the technical issues have become increasingly complex, and the number of available models have multiplied in recent years, this is a good time to take a look at how wireless microphone technology can best suit your needs and applications.

With several hundred wireless microphone models now available on the market the world of wireless can be confusing, but it doesn’t have to be. A better understanding of the basic technology will help you integrate wireless microphones into your church service.

As wireless microphones have become almost standard components of larger church installations, the applications of wireless are more varied and complicated. From the humble beginnings as solo systems used by clergy freely roaming to and from the pulpit, wireless microphones are now often used in multi-channel applications involving several participants (both singers and wireless electric instrumentalists).

Wireless offers the benefits of freedom of movement, less stage clutter and new opportunities for congregation involvement. “Roaming” microphones can be passed around the church, actively involving congregants in the service in new and creative ways. 

Performance of wireless microphones

Wireless microphones are basically comprised of two components: a small transmitter with audio input from either an integral or connected microphone or electric instrument, and a receiver operating on the same frequency. Since there can only be one transmitter on a given frequency, for each wireless audio link there must be a corresponding wireless system.

One of the keys to the high level audio performance of today’s most popular wireless microphones is the use of various forms of companding — a technique originally patented by Nady Systems in the 1970s. Companding basically reconstructs (at the receiver) the full dynamic range from the microphone or source that is lost in radio transmission. Variations in applying this basic technique account for most of the noticeable audio performance differences between available brands and models.

Another important consideration for gauging relative performance in available wireless is the frequency band of operation used. Typical professional wireless systems operate in either the VHF (Very High Frequency at 174-216Mhz) or UHF (Ultra High Frequency at 470-806MHz) bands, with an operating range of up to several hundred feet line-of-sight. At their best, wireless microphones produce audio quality virtually indistinguishable from the wired equivalent. Relative quality depends primarily on the brand and model being used.

Wireless technology evoloves

Both VHF and UHF wireless microphones operate within bands unused by TV channels. Single-channel VHF systems were the norm for many years up to the last decade or so. Although they are similar in performance to UHF systems, and in fact offer some advantages (e.g., longer transmitter battery life, better penetration through large non-metallic objects, lower cost, and generally somewhat better audio dynamic range), new professional installations are almost all UHF.

Large-scale band width users, such as new DTV station allocations, land mobile services, and others are increasingly encroaching on both the VHF and UHF wireless frequencies currently in use. It is very possible that in 10 years wireless systems currently in use will have a much narrower available spectrum, limiting their role. This concern is another factor driving not only the popularity of UHF frequency-agile systems but also stirring interest in new emerging technologies such as wireless microphone systems operating in the 2.4GHz band, digital and hybrid digital technologies. However there are significant trade-offs with the newer systems, not the least of which is the cost — these new systems are considerably more expensive compared to the popular systems currently being used successfully for church applications.

Since larger church installations are more likely to have multiple wireless channels operating simultaneously and even include several wireless in-ear monitor systems, UHF PLL frequency-agile systems are generally the current systems of choice. The better units allow up to 10 simultaneous channels of operation and are available from a few hundred dollars to around $1,000. The more expensive systems generally offer more features in addition to expanded multi-channel simultaneous operation capability.

Special features available

Some added features are not necessarily applicable to church use and are not worth the additional expense. Many of these features are more useful in theater installations or concert halls. Of course, for complex church installations, special features like computer monitoring capability of each channel or built-in automatic frequency selection can be attractive options.

Generally, however, it’s not worth paying the extra high premiums for these added features unless they are required. It’s also worth noting that the basic audio operating range performance of simpler UHF systems can sometimes be better since they’re unfettered by the trade-offs often required for special features.

Another important feature in church applications is diversity reception in the receivers, which is used to eliminate dropouts (null spots) caused by multi-path reflections and cancellations of the transmission. Having audio drop out suddenly during a service is clearly something you want to avoid. So-called “true diversity” performs slightly better than antenna or phased diversities but sells at a higher price and is not generally required. Both techniques use dual antennas on the receiver to pick up the signals independently for processing.

Operating frequency important

If you’re planning to set up multiple wireless systems together, careful frequency planning with the manufacturer or supplier is critical unless you’re working with a sound contractor experienced in wireless installation. Operating frequencies must be selected carefully in order to ensure compatibility of the selected channels. The main consideration here is avoiding intermodulation distortion (intermod) in the receiver front ends caused by the mixing of undesirable combinations of the chosen transmitter frequencies (and even adjacent TV channels), which can cause interference.

During installation it’s also important to correctly plan the placement of the receivers or remote receiver antennas, in order to maximize reliable operating range. In addition, premium low-loss foam core cable (such as Belden 9133) should be used since long antenna cable runs (>50’) can seriously compromise operating range for UHF systems if lower quality cable is used.

Installations of wireless microphones for large churches offer unique challenges. With a basic understanding of how wireless works and knowing the common requirements, you can add the advancement of wireless to your church service with little difficulty and within budget.

 John Nady is founder and CEO of Nady Systems, a wireless microphone technology company in Emeryville, CA. Go to www.nady.com.