Wireless Microphones: The Good, The Bad and The Ksssshhhh!!

I have been using wireless microphones for years on stages and film sets. They are a good thing to have during Q+A sessions with a large audience, but they are not all equal. Even some higher quality brands of the same model act differently than one another and until the technology improves, I never recommend using wireless mics without a back-up plan.

There is Something in the Air Tonight (and Every Day, too!)
There seems to be more and more being fed into the airwaves every day. Now that analog TV is out, I've read (and heard at a technology conference) that those left over frequencies are being bought up by companies who'll use it for wireless internet and cell phone communication. Check out these blurbs (and search for many like them, if desired):

"Many wireless microphones operate in this frequency space (the 700MHz band)....The FCC is wanting the devices to have geolocation services in them, so that they do not operate on known used frequencies in the area of the device. This means that all area devices (wireless microphones) will need to be registered with the FCC....Even though wireless microphones would retain their licensed, secondary use status (secondary only to digital television), the white spaces proposal creates a potential for interference to wireless microphones from unlicensed devices." - (http://production.marshillchurch.org/2009/02/04/fcc-selling-frequency-space)

"White space device prototypes reportedly were unable to detect the transmission of wireless microphones -- for instance, the kind that referees wear on the field -- prompting Shure, the manufacturer of those microphones, to proclaim in advance that those tests will "conclusively show that spectrum sensing white space devices will cause harmful interference to wireless microphones during live events." The FCC itself yet to issue a final report." - (http://www.betanews.com/article/Having-lost-its-own-bid-Google-advocates-giving-analog-TV-space-to-public/1219075156)

Suffice it to say that there is some major concern, especially during live events. At many events, cell phones and Blackberry devices are heard checking or receiving messages with their tell-tale little 'click, click, click' through a nearby speaker system. It's IMPOSSIBLE to ask people to turn off their devices and the AV people are often stared at when this sort of thing happens. We can't do much about it, though.

Different Types of Wireless Microphones
There are two main types of wireless systems in use at live events and film/video productions - VHF and UHF. VHF is Very High Frequency (30MHz to 300MHz) and UHF is Ultra High Frequency (300MHz to 3GHz). The microphone systems operate on a certain bandwidth of those spectrums, with UHF being the better technology for live events.

Every single time I have used VHF live, there was always some sort of interference where UHF offered minimal interference. But, I have had noise problems when certain units had been shut off while the mixer still had it on an open channel. There should always be somebody at the mixer when wireless microphones are being used.

One more thing - two antennas are better than one. One antenna systems have no recourse when the signal fails on the one antenna.

Lavalier Microphones
Lavalier mics (lavs, tie-clip, lapel mic) offer a great deal of freedom for a presenter, but trouble can occur if the speaker system is too low or they go too close to a loudspeaker on a tripod stand. Plus, since they are not directly in front of the mouth, they lack clarity (not to mention the noise that can happen when wardrobe rubs against them).

There is another issue with lavs - they are cumbersome to change over if presentations are back to back and that will create scheduling problems when things run late. Plus, with two or more presenters, the rental costs can be fairly high.

I'm not dead against wireless lapel microphones, but they do have to be planned for in advance if they are to work properly.

Hand-held Q&A Microphones
One can't escape the wireless Q&A for certain types of meetings. For example, when people pay large amounts of money to be at an event, I rarely see them willing to move to far to ask a question. If the meeting were more of a public event, people are more willing to stand in line to ask a question through a wired microphone. Another issue with private meetings and wired mics - you can't put the stand anywhere without it being in someone's way of the screen, unless it's way off to the side.

In any case, a wirless Q&A mic should be UHF and fully tested the day before the event.

Back-up Plans for Wireless Mics
Q&A - if the wireless mic fails in any way (interference, dead battery), audience members should be instructed to stand and deliver, keep it short and ask the presenter to reiterate the question so everybody can hear. Having a wired mic on a stand, ready to go is another great back-up option.

Video recording - VHF mics for video cameras can wreak havoc in a sound system. Even if one could trace and eventually solve the problem, there is very little time before things get underway, so a back-up plan is needed.

Consider asking the AV person if they can somehow 'split' the wired microphone signal in the event of wireless failure. A good AV person will have a few break-out kits with many different cables and connectors to solve many last minute problems. I once installed a mic splitter right at the podium mic to give a video person a feed, just moments before the event was to begin. I could not have done that without a well stocked break-out kit.

Happy wireless and good luck!!

- Buck Moore