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Genius!2: Christian Heil and line array #22

The French inventor launched L-Acoustics patented wavefront sculpture technology which was the original blueprint for modern vertical line array

French inventor Christian Heil, trained in corpuscular physics, launched the V-DOSC full frequency line array in 1993 and, as the saying goes, has never looked back. Well, maybe once or twice…

L-Acoustics’ patented Wavefront Sculpture Technology (WST) was the original blueprint for modern vertical line array and the heartbeat of V-DOSC: since then, the other line arrays in the portfolio have all used the same principles in the vertical domain. What’s changed more recently lies in the horizontal domain: the ability to alter the horizontal directivity pattern of a line array module.

Accordingly, and setting aside several coaxial achievements, two main technological solutions were established: the Constant Curvature line source, namely the ARCS series; and the Variable Curvature line source ranges. The former is recommended for a throw of up to, typically, 35m. It’s derived from WST, but more or less emulates one large point source while increasing SPL using multiple, arrayable elements – not the same as multiplying coaxials, which wouldn’t work. Over 35m, the Variable line source arrays come into play.

While point source is considered ideal for nearfield use – up to 15m – it loses 6dB each time you double the distance, even if the full frequency range does maintain a coherent image. So Heil’s primary goal in the early days was to project intelligibility into the far field – although, for him, it was something of a leap in the dark…

“When I got the idea for V-DOSC, or what became V-DOSC, it was to design a flexible system that combined drivers together – mids, highs and lows,” he recounts today. “Before V-DOSC, the first system that we tried this with was called ‘Incremental’. In my naivety I thought this combination would improve efficiency, but at one particular outdoor festival I realised it wasn’t working properly: the lows and mids were OK, but not the highs. Like in optics, multiple waves combine chaotically, not coherently. I knew more about optics than acoustics back then!

“I went back to the drawing board and saw that I had to create the equivalent of a laser for acoustics, and to do that I had to make a waveform that forced coherence for every frequency. It became all about how to put HF drivers on top of each other and make them work as if it was one single ribbon, and just in case it might work I applied for a patent! I didn’t know if it would, but at least I felt I was asking the right question…

“It seemed so obvious and so easy to do, I didn’t understand why no one had done it before. I had only been in the industry for three or four years, so I began to wonder why this idea had come from me and not from the bigger boys who were around and so well established. Why hadn’t they invented this? I began to be concerned that maybe I’d missed the point, being so junior and inexperienced – maybe there was something I had overlooked.

“But I continued with the tests and, for a while, I decided it wasn’t all that interesting. I let it go for a whole year. Then a good friend of mine – the mix engineer Majid Malki – asked me to show him what I’d been toying with: I did a demo and when he compared it with another system he looked at me and said, that’s fabulous! He helped and encouraged me to re-launch the idea.”

The first festival outings for the new concept convinced Heil that he was onto something, a feeling confirmed by the sudden appearance of interested parties from beyond France at various events at which it became clear that the old bush telegraph was chattering in earnest. “People came from Germany, from Sweden and Holland… well-known people in the industry,” Heil remembers. “At one small festival in Paris we were visited by two gentlemen by the names of Bryan Grant and Mike Lowe (of what is now UK PA hire giant Brit Row)… That’s when you realise, something is happening. After that it’s just a matter of time.”

The line array application established by V-DOSC is solid enough to be completely scaleable – nowadays, in the L-Acoustics portfolio, from KIVA to K1. The pertinent differences between one end of the scale and the other are just SPL capability and bandwidth capability; otherwise it’s the same principle throughout.

Although L-Acoustics made its name internationally through touring, the fixed installation market has always been significant – especially in continental Europe. V-DOSC and its successors raised the profile of the brand on the road and literally, passing through, increased the demand for the products to be kept in one place. Most performing arts centres have broadly the same needs as the touring industry, and many new customers had witnessed an L-Acoustics system in transit and wanted to hang on to it. The differences maybe cosmetic, and a little more cost-effective being installed only once, but the acoustic performance target is the same.

The spirit of genius is restless, though. Heil is now working on a new concept of immersive sound called L-ISA, a DSP engine that effectively creates a 23.1 – as opposed to 5.1 or 7.1 – mix of programme material distributed dynamically between multiple speakers. It’s part of the new corporate structure at L-Acoustics for which, despite much creative delegation, Heil remains the chief architect.

“Word of mouth works very well in our industry,” he reflects, “because the engineers are touring, and talking, all the time. Trends appear suddenly in Europe, as with V-DOSC, and then you have the challenge of the US. Luckily we had Buford Jones supporting us over there, after he’d done the Momentary Lapse Of Reason tour with Pink Floyd and had met us when mixing at a festival in Paris. You can spend a lot of money on marketing, or you can be patient and let it speak for itself. It may happen again with L-ISA – who knows?”

Pictures: Top: Christian Heil in 1985. Second: Christian Heil today. Third: Heil’s former home in Gometz-le-Chatel, just a few kilometres away from L-Acoustics’ current Marcoussis headquarters, 1985. Last: L-ISA technology in action at the Staatsoper Hamburg earlier in 2016.

Published earlier this year and sponsored by QSC Audio, Genius!2 is the second edition of Genius!, celebrating those clever people whose inventions have transformed the world of professional audio. The 30-page supplement is also available to read in a handy digital-edition form