Speaker 1: Did you know that a simple speaker completely transformed modern music festivals, affecting everything from sound quality, festival layout, and stage design?

Speaker 2: When I first heard a vertical line array, I knew as soon as I heard it that that was the way of the future.

Speaker 1: This is Dave. He's a sound engineer and sound system designer who's worked on festivals before and after this change, and has provided audio for Coachella since 2001. How did this speaker affect audio quality? Ideally, you'd only want one speaker to cover an area, but for concerts you need multiple.

Speaker 2: What do we do when you have more than one speaker covering an area? There's two different basic theories or concepts on ways to do that. One is point source.

Speaker 1: With point source, each speaker acts independently, creating multiple sound waves that hit the audience at different times, like a firework or showerhead configuration. This creates inconsistent sound, meaning you'd hear the music very differently if you stand here versus here. So how do we fix that?

Speaker 2: With a line array, we have a speaker, and instead of putting one alongside of it, we put another one above it and below it and above it and above it. Now as you walk across the horizontal domain, walk across side to side, you only hear one speaker. If you were to go up and down, you'd hear the problems, but line arrays pile all the problems up where we hear them least.

Speaker 1: So what does it sound like if you were to walk across a field with a point source speaker versus a line array? What we're hearing is called a comb filtering effect, when interference causes the same sound to be heard with a very small time delay between signals. This is the type of audio interference we'd hear in a point source system.

Speaker 2: Fairly beamy sounding, kind of hot spot in the middle and fades on the left and fades on the right. But what if we take that same thing and we configure them into a line? But look what happens vertically. That's what line arrays do. They allow you to walk side by side and have a very smooth sound, very similar to a single driver because in the horizontal domain, should we slice it, that's all we have.

Speaker 1: Line arrays made sound clearer and more evenly spread so that almost anywhere you stand, the show sounds similar.

Speaker 2: First concert I heard it, it sounded like the PA was closer than it physically looked. It was kind of a messing with my mind. It was how can it sound so close and look so far? I'd never heard anything like that before.

Speaker 1: How did line arrays help create today's festival layout?

Speaker 2: If we have multiple stages on a festival ground, one of the big challenges is preventing sound from this stage from affecting this stage.

Speaker 1: With the use of laser range finders, 3D mapping, and precise angling, sound designers can not only make sure music from neighboring stages don't bleed into one another, but that there are no dead zones throughout the festival grounds. That means that wherever you stand, you're still able to hear music.

Speaker 2: We used to walk into arenas and just draw a bunch of Xs, like put a motor there, put a motor there, put a motor there, put a motor there, and fly them up to 40 feet. And that should do it. It was all eyeballed. When line arrays were released, an acoustics release software that allowed you to determine down to a fraction of a degree the angle between the boxes, we can now aim sound to a certain distance and then have it taper off relatively quickly. We've gained the ability to really cover specific areas.

Speaker 1: We showed Dave images from past festivals to see how much they've changed.

Speaker 2: Here, if you look at this, behind these rainbow scrims, there is 90 boxes per side. Each of those boxes is four foot high by four foot wide. That's huge and heavy. Takes a long time to set up. Fast forward, here's Coachella 2011, also doing a big field gig, and we've gone from 90 speakers a side to these tall, slender line arrays. This was 2001, the first year that we did it, and here we can see the Rattrap rigs, a system I designed that is four deep, six wide, kind of an old school system before the true line arrays came into play. So this is when we bought our first VDOS rig, and there is the line array. The festival's grown, and you can see that there's less PA, or seemingly less PA, yet the volume and coverage was actually louder. Now this one here, it looks bigger. It's actually two line arrays side by side, and that's my fault. Line arrays should never be put side by side. They interfere with each other, but I solved it by not running the same signal into both. I actually have two PAs here. One for vocals and drums, and another one for guitar and bass. They were completely separate, and that was absolutely amazing. And here is the first year we got the new system. This is a K1 system, so now we could hang 24 boxes deep instead of 14. This was the largest deployment of this sound system that had ever existed in the world to date. Look at the change in this year, from those drops, and then video screen behind, to video screen. There's guns in rows. Look at that. It's taken that sharp edge out of the screen and made it smooth, and that's all high-resolution video all the way across. If you really think about it, we want to hear sound. We don't want to see it. If we could make the sound system invisible, we will have one. We want to just hear it, and line arrays helped us get a heck of a lot closer to that.