This guide, like all the others at MagicRoadie.com, will not include advice on brands or models to purchase or rent, and won’t make much mention of the underlying scientific principles that are at play. It’s more like an “applications” guide, with proven advice on how to make your wireless system (heretofore referred to as an “RF” system) work as well as possible. Proven advice … not based on hearsay … not based on urban legends. RF application is science, not voodoo. There’s no way to make your RF system work perfectly, but there are things you can do to make it work better, and there are things you can do to make it work worse (Nice grammar, eh?).

Should you go wireless?
A huge chunk of my daily professional life if spent understanding, and maximizing the performance of, wireless entertainment equipment (mics, two-way radios, theatre communications, and in-ear monitors), and still, my first choice is always to use a hard-wired (non-RF) alternate. I’m not sayin’ wireless is evil, but I am saying it’s less reliable than its hard-wired brother. There are, however, obvious arguments for using wireless mics: Mobility is the most common. If you’re wandering around a stage, producing doves or executing elaborately choreographed musical transitions, you can’t be draggin’ a mic cable around with you!

Here in Part 1 of this guide, we’ll look at some “urban legends” concerning RF systems. In Part 2, we’ll look at how to make them perform best.

Urban Legend # 1 – “What wireless system does Copperfield use? His never drops out!”
The possibility of RF dropouts is a pure & simple fact of life. Even the most expensive RF system, operated by world-class RF techs, is susceptible to dropouts and other interference. The good news is that this guide will help you to minimize them.

Urban Legend # 2 – “What wireless system does Copperfield use? His sounds GREAT and never feeds back!”
Assuming we're comparing systems of professional quality, anywhere from "entry level" pro to "Broadway" pro, the wireless system has almost nothing to do with sound quality or feedback. Basically, sound quality & feedback are functions of microphone selection and PA operation. The quality of the wireless system affects dop-outs, interference, and other non-sound-quality-related issues.

Urban Legend # 3 – “The big theatre pros just tuck their beltpacks into special pockets.”
While this is true, keep in mind that the beltpack’s antenna must be allowed to extend to its proper length for maximum efficiency, and must not be touching anything conductive, including skin. Sweaty skin is even worse.

Urban Legend # 4 – “UHF is better than VHF!”
This is simply not a fact. Each type has its own strengths & weaknesses. Here are some facts.

- VHF (very high frequency) and UHF (ultra high frequency) are quite simply two ranges of radio frequency (RF). Both types can perform very well, and each has pros & cons.
- It costs more to manufacture a UHF system than a VHF system, and the lower purchase price of VHF systems is a reflection of this fact, and not a refelction of quality or relaibility.
- VHF is better at dealing with “line-of-sight” issues like walls, doors, and even bodies. Yep. Your body can be a very real, physical impediment to the performance of an RF system. Unfortunately, with any RF mic system, the transmitter must be right next to your body (especially in the case of a bodypack).
- It’s much easier to find "tunable“ or "frequency agile” systems in the UHF range. A tunable system has more than one frequency. You only use one frequency on any given system at a time, but if there’s a problem on one frequency, you can reset
the transmitter & the receiver to another in order to find one that is “clear”. You can also use multiple systems simultaneously.
- You can simultaneously use more UHF systems than VHF.
- UHF can sound better than VHF, but, in my opinion, unless you’re working in film or TV, the inherent quality difference is not evident. There is a much greater difference in sound quality as a result of product quality, microphone selection, and applied audio skill.
- UHF systems can generally be used in conjunction with VHF systems at the same location without interference.
- If you use an RF mic only occasionally, and if all of your work is indoors, and if you’re always within 5-8 metres (15-25 feet) of the RF receiver, I think you’ll do fine with a good quality, non-tunable, VHF system, because it’s inexpensive and you’re not a target for interference. Otherwise, in my opinion, a frequency agile UHF system is the only way to go. It’s more expensive and is marginally less capable of dealing with physical obstacles, but its agility is a tremendous boon. During your sound check, while it usually won’t be necessary, you can take a couple of minutes to find a clear frequency.

Urban Legend # 5 – “As long as two RF systems aren’t on the same frequency, they won’t interfere with each other.”
Not true. The math behind finding simultaneously compatible RF systems is pretty involved. Even if no one else is using a wireless system, you might encounter problems. If you plan on buying or renting more than one system, make sure that the vendor has ensured compatibility between them. The manufacturer is an even better source of info on this. Remember, as well, that the interference you encounter will change from city to city and from venue to venue, and can even affect a portion of your performance area as small as 7.5cm x 7.5cm (3” x 3”)!

In the US & Canada, all of the RF systems that the law allows us to use is in the same frequency range as VHF & UHF TV (channels 2-13 and 14-69), so, especially if you work in a major centre, be sure to check with the manufacturer about “broadcast TV compatibility”.

Digital audio signal processors, digital recording and playback devices, hard drive recorders, digital electronic musical instruments, MIDI-controlled instruments, and stage lighting controllers can all cause buzzing in your RF system, so do your best to avoid having your transmitter or receiver within a few feet of them. Close proximity to stage lighting dimmers and neon or fluorescent lights can also be a big problem.

Urban Legend # 6 – “The store said my RF would work up to 300 feet!”
Due to the countless variables one might encounter (obstructions, reflections, RF interference), it is impossible to predict the useable distance of an RF system, so don’t believe what the store or even the manufacturer tells you. Besides, a cardinal rule in the use of RF is to maintain the shortest possible unimpeded line-of-sight between the transmitter’s antenna and the receiver’s antennae. Don’t make distance an issue!

Urban Legend # 7 – “You save save a bundle by using rechargeable batteries in your RF transmitter!”
Use the batteries that are recommended by the system’s manufacturer. These will usually be alkaline batteries because alkalines are more reliable, have a much greater useable life and a greater shelf life than other types. Typically, you can use re-chargeables about 1/10th to 1/20th as long as regular alkalines. Buy ‘em in bulk because the price will be lower, and their shelf life (printed on the battery) is usually a few years!
Turn the transmitter off between performances to extend battery life, but do not turn it off during the performance, because you’ll occasionally forget to turn it back on.

Urban Legend # 8 – “It's best to keep the receiver at FOH!”
One of the most unknown and/or deliberately unobserved rules of RF usage is that sound people choose to put the receiver at FOH (the “front-of-house” mixer position) so that they can see the RF level (RF signal strength) meters. Unfortunately, this also means that since the RF is having to travel a greater distance, and since there are more human obstructions along the way, the signal strength will be compromised! So, basically, the choice is as follows:
a) Keep the receivers at the stage where you’re not able to see them, and know that they’re performing better, or,
b) Keep the receivers at FOH where you are able to see them, and know that they’re performing worse.
Always chose “a”.

Well, that’s the end of Part 1, and the urban myths surrounding wireless mics! Tune in next time for "Wireless, Part 2", with proven advice on how to make your wireless system work as well as possible.

Enjoy!

Dan McLean Jr
MagicRoadie.com