Another 600 MHZ Update

Hey y'all. As we wind down summer, a little tidbit came across the desk of one of our engineers, Steve Lund. He was pursuing some info put out by James Stoffo of Radio Active Designs. James does a lot of work coordinating wireless gear for things like the Super Bowl, the CMAs, and pretty much every major award show. I actually met him at the CMAs a few years back. Great dude. 

Anyway, shared this map that came from Professional Wireless Systems. This shows the counties that T-Mobile is planning on lighting up starting November 1. Of this year. 2017. So if you happen to live in one of the little green squares, and you have a wireless mic or IEM running above 617 MHz, you're going to need to shut it down after Nov. 1.

Remember, it's not a matter of interference. By law, once the new owners of the spectrum start testing, every other operator needs to cease using it. Could you get away with it? Maybe. Should you? No. 

There's a little early Christmas gift for you. Time to order up those new wireless units, or better yet, wire everything you can. This isn't going to get easier going forward...

UPDATE: I've been asked about a larger map. Can't find a larger map, but I did find this spreadsheet of counties that presumably generated the map in question. So, there you go.

600 MHz Spectrum: A Quick Update

Somewhere out there you may not have noticed that the FCC has once again sold off a bunch of spectrum. They had such fun during the last sale, they just couldn't help themselves. We've done a few podcasts on this already, but there is a little new information I thought would be helpful to get out there. 

Being dealers, we just received this notice from Shure. This notice comes down from on high--which means it came from the FCC. This little ditty is supposed to be put at any point of sale of wireless equipment. It's instructive, strangely enough. 

This particular wireless microphone device operates in portions of the 617-652 MHz or 663-698 MHz frequencies. Beginning in 2017, these frequencies are being transitioned by the Federal Communications Commission (FCC) to the 600 MHz service to meet increasing demand for wireless broadband services. Users of this device must cease operating on these frequencies no later than July 13, 2020. In addition, users of this device may be required to cease operations earlier than that date if their operations could cause harmful interference to a 600 MHz service licensee’s wireless operations on these frequencies. For more information, visit the FCC’s wireless microphone website at www.fcc.gov/wireless-microphones-guide or call the FCC at 1- 888-CALL-FCC (TTY: 1-888-TELL-FCC).

The key takeaways are this: If you have any wireless equipment operating pretty much anywhere above 617 MHz, you need to begin making plans to replace it. At the very latest, you'll have to shut it down permanently on July 13, 2020. However, I've heard from multiple sources that the new owners are so excited to try out their new spectrum that they will be firing stuff up as early as this fall. 

In the past, we've had a little more time to transition, but this time, if a wireless carrier fires up something at, say, 625, and you start causing them interference, you will have to shut down. More likely, they will be causing you interference and you'll need to move or shut down anyway. 

Given that the wireless manufacturers are once again offering some decent rebates to trade in your 5-year old wireless gear that you bought when the 700 Mhz band was sold off, I wouldn't wait too long (most rebates go through year's end). 

This is likely to happen again in a few years, so I would recommend you cut down your wireless channels to the absolute bare minimum and go as low as you can go frequency-wise. Those in urban areas will probably feel this before those in the country do, but know that this is coming, and you're going to have to come up with a plan. Hopefully you've been listening to CTW over the last year as we've given you fair warning. 

So, there you go. Your friendly wireless spectrum update for August 3, 2017. Enjoy an interference-free weekend (while it lasts!). 

CTA Reviews: DiGiCo SD12

Taking a break from my sabbatical--which is sort of odd since a sabbatical is taking a break--to post this video we shot of the DiGiCo SD12. DiGiCo was kind enough to loan me one so I could re-shoot the audio training class for SALT University. 

No doubt you know, if you've followed me for any length of time, that I'm a huge DiGiCo fan. I was into them before they were cool, having bought an SD8 in 2010 for Coast Hills when I was there. I have to say, the SD12 may be my new favorite desk. It's small, powerful and very cost effective. 

The dual screen configuration is super-cool, and I'm just a huge fan of the workflow. But who cares about all this typing, let's get to the video!

Learn more at: http://www.digico.biz/docs/products/SD12.shtml

UPDATE 7-28-17: In the video I state that all channels and busses can be mono or stereo. That is not technically correct. While any of the channels and busses can be mono or stereo, there are processing limits that prevent them from all being stereo at the same time. The SD12 currently has 72 processing channels and 36 processing busses. How you arrange them (mono or stereo) is up to you. Sorry for the confusion, the video is updated with corrected title states.

CTA Review: L-Acoustics ARCS

One of my favorite PAs to date; Northview Church in Anderson, IN.

One of my favorite PAs to date; Northview Church in Anderson, IN.

It’s been a while since I’ve done a real equipment review, and I figured it was about time. I’ve been holding off on reviewing these speakers until I’ve had experience with them in multiple venues. In the past, I’ve found that speakers can sound OK (or terrible) in a demo space, or maybe even sound good in one application. But before I can give an entire system a thumbs up, I wanted to hear it in multiple venues of varying shapes and sizes. 

Spoiler Alert

I’m a huge fan of these boxes. There, I said it. I have now designed and commissioned four ARCS systems in three different styles of rooms and they have excelled in all of them. In every case, I’ve been able to achieve incredibly even coverage throughout the venue while maintaining a high level of sound quality. It’s hard to ask for more than that. 

Let’s talk about the system components. There are three models in the ARCS series; the Wide, the Focus and the ARCS II. The design of the boxes is somewhat unique in that they can be arrayed in both horizontal and vertical arrays. They don’t become a true line array when you hang them together, instead they cover the audience areas in sections. 

The ARCS series marketed as a medium throw system, up to around 35 meters. In practice, I have found this to be pretty accurate. My last system was in a room about 80’ deep and while we covered it very well, I was gaining the top box up about as high as I could to get the SPL we desired back there. They tend to work perfectly in the 50-80’ wide by 50-70’ deep 400-600 seat venues currently popular with modern churches. 

The Wide box is a 90°x30° coverage pattern rated from 55 Hz-20 KHz with a max SPL of 135 dB. The Focus box is the same except it is based around a 15° vertical coverage pattern. The ARCS II is 60°x22.5° and will reach down to 50 Hz while delivering 140 dB SPL. While the Wide and Focus boxes are built around a 12” LF and 3” HF driver, the ARCS II has a 15” LF and 3” HF driver compliment. 

Matching Power

Like all L-Acoustics systems, the ARCS have to be driven by an L-Acoustics amplifier. We typically use the LA4x, though depending on the design, the LA8 or LA12x will work equally well. The LA4x is a 4x1000W amplifier, and each channel drives one ARCS box. Each L-Acoustic speaker series has a pre-built amp preset that works some pretty great magic on the speakers, and they require very little EQ to make them sound great. In fact, the first time I commissioned a system, the construction project was so far behind that we didn’t get time to do any tuning of the PA prior to the first service. Even with nothing but the stock presets, the mix sounded great and everyone was happy. 

I’ve found the bulk of my time in commissioning an ARCS system is spent getting the delay times set correctly and doing gain shading to get the levels consistent front to back. I usually do 1-3 small EQ filters to correct a few minor things in the boxes, then apply a global EQ for tonal shaping of the PA and that’s about it. 

Even Coverage

For me, a huge design goal of any PA is evenness of coverage. Internally, we have a design standard that shoots for ±3 dB or less of variance across the seating area in the 1-4 KHz range. Personally, I shoot for ±2 or less. With the ARCs systems, I’ve always been able to hit that mark. Here are a few traces from the last system I worked on. The pink trace is the center of the house right section in the front row. The blue trace is in the same spot, but in the back row. As you can see, overall, it’s pretty darn close. Overall SPL was within .5 dB and aside from a few acoustical anomalies (the room really needs some treatment), frequency response is very similar. 

Pink trace = front of the room; Blue trace = back of the room

Pink trace = front of the room; Blue trace = back of the room

    More than evenness, the ARCS are musical. In fact, they are some of the most musical speakers I’ve heard. Because they act more like a point source box than a line array, the phase response of the system is very coherent. L-Acoustics has spent a ton of time and money refining the porting and waveguides of all their speakers to deliver very phase coherent sound, and it shows. Even the smallest details of the music some out clearly, and the low end never overwhelms the clarity. When combined with the SB18i subs (which will likely be the subject of another post), the overall system is one that I just want to keep listening to. In fact, in every case, when I’ve been commissioning a system, I’m usually done in about an hour to hour and a half, but I keep playing tracks and walking the room for another few hours because it just sounds so darn good! I keep throwing more tracks at them and they rock it each time. 

Surprisingly Affordable

I always had in my mind that L-Acoustics was the premium-priced brand. And to be sure, the higher end line array products can get pretty pricey. But the ARCS—and in particular the wide and focus boxes we are using in most cases—are very affordable. We’ve found them to compare very favorably to systems that don’t sound nearly as good out of the box, even when the somewhat expensive amps are taken into account. 

And that brings me to the two things I assign to the negative column of the ARCS. First, you have to use the L-Acoustics amplifiers; or as they call them, amplified controllers. I once asked our rep about using another manufacturer’s amp for some front fills and he said, “Yeah, don’t even suggest that.” Now, on the positive side, the amps with the factory presets are fantastic. I wouldn’t not want to use them, I just wish they were less expensive. 

Second, when going from a focus box (typically on the top of the array) to a wide box (typically on the bottom), there is a slight gap in coverage. It’s very minimal—on the order of 2 dB or so—and would only be noticed by people listening critically while walking forward in the coverage pattern. But it is there. It’s a zone that lasts about 1-2 rows depending on chair spacing. As I said, most people sitting in those chairs aren’t going to notice. But if you play a track with a lot of HF detail, you’ll hear a little dip as you move through that zone. Otherwise, they just work.

Like all speaker systems, the ARCs aren’t right for every application, or even every budget. However, if they are a fit for the space and you have the funds, they are an excellent choice.