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.