Last time, we looked at the basic building blocks of the Axient system, namely the AXT100 body pack, the AXT200 handheld and the AXT400 receiver. We finally got to hear actual voices and instruments played through those components for the first time, and I was impressed with the overall sound quality (especially on vocals). The RF section is solid as well. But if these three pieces are the cake, the next few pieces of the system are like a really good gnache frosting. Let’s start with one of my favorite pieces, the AXT600 Spectrum Manager.
The Spectrum Manager is basically a wide-band RF scanner that constantly monitors the RF landscape, building a list of interference-free, compatible frequencies for the systems in place, and hands them out as needed. Put this in a two- or four-space rack and pair it with Wireless Workbench 6 and you have a killer RF spectrum management tool. At the most basic level, Spectrum Manager will build the list of main and backup frequencies for your gig. You can manually assign those frequencies to the gear on the network, then use IR to pair the transmitters. That’s nice, but it gets so much cooler.
The next piece of the system is the AXT610 ShowLink access point. The engineers at Shure were clever enough to include 2.4 GHz radios into each of the transmitters that will talk back and forth with ShowLink. They used the Zigby protocol, so it won’t interfere with WiFi networks. Each 610 can control up to 16 transmitters and gives you complete control over every adjustable parameter of the transmitter. Ever set the gain on a handheld and get back to FOH during the gig and see the audio meters pegging into the red? With ShowLink, you can just dial that right back. Or if you want to save battery life, you can mute the RF section between sets. But it gets better.
When paired with Spectrum Manager (I told you it was a system), Axient can automatically detect and avoid interference. Yes, you read that right; RF hits on your wireless mic’s are a thing of the past. Here’s how it works. Say your handheld is tuned to 625.00 MHz. And let’s say someone shows up with one of those fancy new TVBD (TV Band Device) wireless internet gadgets (they’re coming; just wait!), and it’s also operating on 625. When that little bugger fires up, it would knock a conventional wireless system off the air. But the Axient receiver sees the interference and requests a new, clean frequency from Spectrum Manager (which always has a list of several dozen standing by). The receiver re-tunes to the new frequency, and ShowLink tells the transmitter to retune as well. This all takes place in under a half-second, and the audio dropout is barely audible.
In fact, when the Shure folks were deliberately tuning to channels in use by the band, we didn’t hear anything; there was enough sustain and overall volume to cover up the incredibly brief audio dropout. And we never heard any fuzz, hiss or RF noise. Now, what I’ve just described is the single-channel operation. Personally, I think it’s good enough for 90% of wireless applications. But for that last 10% where even the slightest audio dropout is unacceptable, you can switch to frequency diversity mode.
As I mentioned last time, the handheld has two complete RF radios in it and can tune to two frequencies at once. To use frequency diversity, you put the receiver in frequency diversity mode, and like RF diversity, it constantly compares the the signals coming in and outputs only the clean audio. All the audio switching is done in the receiver; all four outputs (ch 1&2, analog and AES) output the same signal, so there is nothing the FOH engineer has to do. If one channel takes a hit, the system goes through the re-tuning process I just described, but only after switching to the clean audio.
The result is completely uninterrupted audio at all times. It was really impressive to watch both Jenn and David trying to knock the band’s wireless off-line during an entire song. They had multiple transmitters that they were tuning to the band’s frequencies, and Axient just kept moving around the interference. It can be set up to happen completely automatically, or only after a human confirms the change.
If you are using body packs, you can also use frequency diversity; however you need to to use two body packs. This is a specific design choice made based on user feedback. The broadcast guys said they were going to double-mic the talent anyway, so they might just as well have two packs. Otherwise, the system works the same.
By now, the system is getting pretty impressive, but like a late-night infomercial, just wait! There’s more! And we’ll get to it in the next post.