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.

Tech Power

Image courtesy of  Oran Viriyincy

Image courtesy of Oran Viriyincy

So a funny thing happened on the way to the website…Just as I was getting ready to post the last post of 2016, I got a notice that my security certificate was invalid. Knowing that I needed to touch up my domain config and enable SSL, I decided to click those buttons. What could possibly go wrong? Well, after knocking CTA out for a few days, we’re back. And now it’s 2017! But this is still a good post, so here it is the last post of 2016, and the first post of 2017…

As I was thinking of topics to wrap up the year, I wanted something powerful, something electrifying, something high-voltage. Then it occurred to me that I’ve not done a post on technical power. And since pretty much everything we use every weekend runs on power, it’s kind of an important topic. Power is also something often overlooked during a build or remodel. Many of the problems we have with sound and video can be traced back to bad power. There’s actually a lot to this subject, and I’m not sure I can cover it all in one post. But let’s see how far we get.

Go To Ground

At some point, all power ends up at ground. After it has done its job, power goes to ground. And that’s where problems tend to crop up. I’ve seen many a church wired up with the stage power coming off one panel and the tech booth power coming from another. Electricians do that because it may be easier for them, and they really don’t understand what we do. The problem comes in when there is a different ground potential on those two circuits and we connect them together with audio wiring (or video wiring, for that matter). 

How do we connect them together? Let’s say your amps are on the stage panel, while your mixer is on the tech booth panel. Connect your mixer to the amps with a balanced audio cable. The ground (shield) on said cable connects to the chassis grounds on both the mixer and the amp. Guess where those chassis grounds connect to? The ground pin in the outlet.

Now, let’s say we have 3-4 volts on the ground leg of the stage panel and 0 on the tech booth panel. That little voltage will flow over the shield and induce hum into your signal. 

It is for this reason that when we specify tech power, we always specify dedicated, isolated ground panels. An isolated ground isolates the neutral bus from the ground bus. I won’t go into technical details here, but it goes a long way to prevent what I just described. We also always specify this IG (isolated ground) power for the audio and video equipment. Lighting gets put on its own panel. In a pinch, if budget is tight and the lighting rig is small and LED, we can pull lighting power from a general-use panel. But never from the AV panel. 

Isolation Power

We also like to isolate the incoming power from the power company. I’m a big fan of using isolation transformers in front of my AV, isolated ground panels. This de-couples the tech power from the power company power and cleans it up a lot. While an Iso transformer can cost thousands to tens of thousands of dollars, it’s really good insurance. There’s nothing worse than hum or bitrate errors in your brand-new $300,000 AV system because you tried to save $7,500 on a transformer. 

Power Segregation

It’s important to segregate your power usage in the booth and on stage. In all the venues we design, I specify AV circuits and lighting circuits in the tech booth and on stage. The AV circuits should be clearly labeled (orange outlets are good) as IG and only AV gear gets plugged in there. Any floor-based lighting fixtures (along with lighting consoles and distro gear) get plugged into the lighting circuits. 

Sequencing

We will often use either relay panels or a motorized breaker panel for turning the system on and off. We like Lyntec, but there are other brands available. Sequencing allows you to press “On” and have the entire system power up in the right order (mixer and stage racks before amps). It goes back off in the opposite order. It’s also important to have both sequenced and non-sequenced AV circuits in the tech booth. Often, you will want to leave computers or other devices like UPS’s on all the time, and you don’t want them shutting down with the sequence. Speaking of UPS…

Split Your Power Supplies

It’s a good idea to put your critical gear on a UPS (uninterruptible power supply). This battery backup will cover you forfew minutes in the event of a short power outage or blip, and will give you time to shut down gracefully for longer outages. Mixing sequencing and UPS can get tricky, however. If you put your mixer on a UPS, you can’t put it on the sequence. It has to be manually powered up and down. 

Also, if your console—or any other piece of gear—has dual power supplies, don’t put them both on a UPS! If the UPS dies mid-service, and I’ve seen and heard of it happening more than once, you lose your console. Plug one power supply into the UPS so if you lose house power, the console stays up. If you lose the UPS, the console stays up.

Surge Protection

If you live in an area where storms are prevalent or your power isn’t very stable, surge protection is very valuable. Lyntec (and others) can install transient surge protection in the panels, and while not inexpensive, it might just save your $10,000 projector. We always specify TSP for our AV circuits, and if budget permits, lighting circuits as well. You can also do local surge protection if the budget doesn’t allow for panel-based TSP, though it may not be as effective.

A Balancing Act

Budgeting for all this power is a bit of a balancing act. Doing power correctly for a mid-sized AV system can easily add $25,000-30,000 worth of electrical gear to a project. If your PA/Mixer upgrade is a pair of self-powered $1,200/ea. speakers and an X32, that’s probably overkill. But if you’re spending a couple hundred thousand dollars on the system, it’s money well-spent. The key is getting it designed properly. I’ve seen some designs that are so grossly over-done that the church probably wasted $40,000 on power gear they’ll never use. On the other hand, going to small will limit you in the future. You have to know the long-term plans for the room. I like to have at about a half-dozen empty circuits in the panel board, unless the building will be greatly expanded. Only then are more appropriate. Then again, I’m working with a church right now doing a PA upgrade, and we need 6 new circuits for the amps, DSP and wireless rack. Having open space is a good idea. 

There’s probably much more I can say about power, but I’ll stop for now. Being that this is the last post of 2016, I want to thank you for reading this year—and in years past—and hope you’ll stick around for 2017. Next year, ChurchTechArts will be 10 years old, something I never envisioned when I started. Thanks to those that have stuck around from the beginning, and to all the new readers that just joined. I have some news for 2017 that will hopefully generate some excitement, but we’ll wait until next week for that. Happy New Year!