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AKG - DMS700: A professional digital system operating in the UHF band between 548 - 698 MHz; frequency-agile over 155 MHz; scan and spectrum analyzer functions in 1RU / 2-channel receiver; wide audio bandwidth with 24-bit/44-kHz sampling rate; latency of < 4 ms; variable transmitter power levels; encryption; analog and digital outputs; Ethernet for computer control.
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Sennheiser Evolution D1
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Sony DWZ
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Line 6 XP-V75
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Shure GLX-D
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Audio-Technica System 10 Pro
As the allowed frequency spectrum for wireless microphones steadily shrinks, many churches are scrambling to figure out what kind of systems will be a safe bet for use long into the future. The good news is that microphone makers have responded with plentiful options. But if you choose the wrong one for your particular needs, you could be sorry.
In last December's issue of Church Production, we took a broad overview of the analog and digital system offerings in the three basic available bands: UHF-TV, ISM and VHF. In this article, we will focus in on the so-called “Wi-Fi” systems, which is really a misnomer. So let's at least get our definitions straight.
WIRELESS DEFINITIONS
Wi-Fi:
This trademarked term refers specifically to systems for wireless connection to a local area network (LAN). In other words, it's the access point you use for wireless Internet connections. In the United States, most of these systems operate in the 2.4 GHz band, the same as for most of the microphones we're looking at here. Thus the confusion … but I won't use the term anymore.
2.4 GHz:
This band is a chunk of frequency spectrum that extends from 2.400 GHz to 2.483 GHz.
ISM band:
ISM stands for Industrial, Scientific and Medical and it refers to about a dozen frequency bands defined by the International Telecommunications Union for purposes other than wide area telecommunications. Some like 2.4 GHz are open for license-free use worldwide, while others (like the 900 MHz band we'll note in closing) are restricted on a regional or national basis.
YOU'RE SAFE WITH 2.4 GHz IF:
You want to be worry-free about FCC spectrum auctions :
– Many of us vividly recall those days in 2010 when we had to relinquish use of our 700 MHz band systems. We had to replace four perfectly good units at our mid-sized church, half of our total at the time. And yet another FCC spectrum auction looms on the horizon. But you're safe with 2.4 GHz. It's not going anywhere.
You want ease of use:
– Just like the Wi-Fi access points that are their kissin' cousins, ISM wireless microphones are extremely easy to set up and use. Channel selection and pairing of receivers is a painless pushbutton procedure. Also, these systems are very good at automatically sniffing out the best frequencies, and—at least up to a point—they can hop around any new interference that pops up.
You're looking for good performance and an excellent features-to-cost ratio:
– Overall performance on these systems—all are digital, of course—is as good if not better than either digital or analog UHF band systems at the same price point. Often you'll get even more step-up features. Pricing is highly competitive, with many very good systems at or under $500 per channel.
You want to tour worldwide with it:
– Okay, it's not that important for most churches. But the fact that the manufacturers can sell the same unit worldwide helps keep down the costs.
"If you’re in a tight-packed commercial or residential neighborhood, you could get interference from adjacent buildings…."
HOWEVER, 2.4 GHz WILL MAKE YOU SORRY IF:
You need a high channel count at one location
– Twelve simultaneous channels are the maximum you could hope for simultaneously, and that's with absolutely ideal conditions. Most makers stop around eight, and hedge down to four or five if you have many other “Wi-Fi”-type systems operating in the same room or nearby.
You need long transmission distances, especially outdoors
– The short wavelengths of this band (less than five inches) make it more important to maintain line of sight between transmitter and receiver, since the waves are more easily absorbed by people and walls. On the up side, the small wavelengths reflect off walls and ceiling, potentially boosting signal a bit. However, in very large rooms or outside, without reflection boost, operating distance will be less than with equivalent UHF systems.
You have lots of other gear that uses the 2.4 GHz band
- If your worship auditorium has multiple other systems occupying the 2.4 GHz band, like Wi-Fi Internet access, a digital mixing console with tablet remote or remote video camera controls, all of these could interfere and limit operating distance, reduce channel count, cause dropouts, or combinations of all three.
You can't control other users nearby
– If you're in a tight-packed commercial or residential neighborhood, you could get interference from adjacent buildings. Best to sniff out any potential problems using an app like Wi-Fi Analyzer for Android.
You need remote antennas
– Line loss at 2.4 GHz is much higher, so you'll need more expensive coax cable and/or in-line booster amplifiers. Some models do not have connections for remote antennas.
That's the general rundown. If you're still feeling more safe than sorry about this gear, let's look at some typical 2.4 GHz models. Although they share many similarities, you'll find them packaged with a variety of feature sets.
AKG DMSTetrad
– This system is unique in that it comes with a four-channel receiver as standard, all in a 1U metal cabinet. Basic systems come with one mic, and you can add on as you please with handheld, headworn or instrument transmitters. Each channel has its own balanced output, but it also has a built-in mixer for summing to a single output. Sound quality is excellent since the digital guts use 24-bit/48 kHz processing. A starter system with a single P5 handheld has a street price of about $700, and you can add more mics for around $200 each. If you max out, you're paying only $250 per channel, which is a pretty good deal. Add $50 per mic to move up to AKG's premium D5 dynamic capsule.
Audio-Technica System 10 Pro
– With this step-up system, Audio-Technica engineered a nifty solution to the remote antenna problem noted earlier. Instead of a remote antenna, you get a remote-ready RF input module. One or two modules can slide into the receiver frame (which has the audio outputs and display), or they can be stuck near the stage up to a 300-foot distance and connect to the receiver frame by CAT-5 cable, which also carries DC power so you don't need a local wall wart for it. Pretty much everything is a la carte, so you can have one or two receiver modules and pair them with handheld or bodypack transmitters. The digital technology employs three levels of diversity—time, frequency and space (dual antennas)—to maintain signal integrity under difficult conditions. Single systems start with street prices around $430 and dual systems go up to $800.
Line 6 XP-V75
– Line 6 was an early pioneer of systems in this band and, in fact, only offers systems working at 2.4 GHz. The XP-V75 is the flagship of the line, offering 24-bit digital processing for clean, uncompressed sound from subsonic (10 Hz) to 20 kHz. What sets this system apart from the pack is the sophisticated, built-in signal processing. The handheld version gives you selectable emulations of 10 popular vocal microphones, so you can tune and re-tune to suit any singer in the group. The lavalier, headworn and instrument systems have nine different digital EQ filters to fine tune for the application at hand. The instrument bodypack version sells for $450, with a $500 tag on the handheld, lavalier and headworn versions. If you can get by with only four mic emulations and a simpler interface on the receiver (no LCD screen), then check out the XD-V55 for about $100 less.
Sennheiser evolution D1
– Sennheiser was a bit late to the game in the 2.4 GHz band, but made up for lost time with a high-performance, feature-rich system. The “digital brain” inside is extremely sophisticated, allowing a generous channel count and uninterrupted performance even with surrounding Wi-Fi and Bluetooth interference. Intelligent channel backup instantly and seamlessly switches to a pre-identified backup channel should new interference suddenly butt in. Frequency management is fully automatic, and you can exercise remote control via LAN or smartphone (Android or iOS). Other nifty features include automatic input gain control and remote battery monitoring. Street prices start around $650.
Shure GLX-D
– This is a rugged, smartly styled and well-thought-out system for novice users. At the heart of the system is Shure's LINKFREQ technology, which quickly analyzes the entire spectrum, determines the best frequencies, and automatically assigns them to the transmitter and receiver. In the event of naughty interruptions, the two jump to a better frequency with no audio glitches. For transmitters you can choose handheld (with a wide selection of Shure capsules), bodypack (selection of lav and headworn mics), or—unique to Shure—a floor stompbox transmitter. A handheld system with an SM58 capsule hits the benchmark street price of $500 spot on.
Sony DWZ
– A style leader with its bold color LCD display and bright-ringed level control, this system also maintains impeccable performance with 24-bit linear processing along with an on-board five-band graphic equalizer and intelligent feedback control. Also unique at this price point is a handheld transmitter with replaceable mic capsules. Packages are available with basic and step-up handheld capsules, as well as bodypacks with headset and lavalier. Street prices are, respectively, around $550, $700 and $730.
The Other ISM Option: 900 MHz
All of the above systems are in the ever-so-popular 2.4 GHz band, slugging it out with Wi-Fi, Bluetooth, mixer remotes and even thermostats. (Our church has several.) Is there fresher air somewhere else?
Definitely … maybe. As mentioned before, there is another ISM band, down between 902 and 928 MHz. But this may or may not be a clean scene in and around your church. In addition to vintage cordless phones, this spectrum is inhabited by “walkie-talkies,” baby monitors (check the nursery), smart power meters and video camera remotes. Sodium vapor lighting can emit RF in these frequencies.
So, although far from perfect, it could be better than 2.4 GHz in some circumstances. And it is available license-free here in the Western Hemisphere, but apparently not so elsewhere in the world. That lack of worldwide use may be inhibiting development of wireless mics, but Shure decided to jump in anyway and offer three systems in this band. (Presumably the company had to develop its own 900 MHz tuner chip and just plug it in. But developing a custom chip is costly.)
So yes, you can get Shure's entry-level PGX-D (roughly equivalent to GLX-D), the mid-level QLX-D and premium ULX-D systems for operation in the 900 MHz band. But Shure advises caution, and strongly recommends you avail yourself of the Site Survey tool in its Wireless Workbench spectrum management software. Check out the RF competition carefully.
And make sure those baby monitors are ON in the nursery before you scan for interference.
