The icing on the cake? Christian Heil granted us an interview. We reviewed the essence of the L-ISA project, the IT tools needed to implement it and, finally, his vision of modern amplified sound.
More than exciting… Essential.
SLU: A persistent legend would have it that you had the idea for L-ISA one day after a concert where you, like 90% of the audience, were poorly positioned.
Christian Heil (President L-Acoustics…): It didn’t happen in one day; it’s been a problem for a very long time. When I founded my company 30 years ago, I didn’t know what sound reinforcement or live production were, I was only interested in the technology that we were helping to move forward and that satisfied us for many years.
Little by little, I put together teams of sound engineers and application engineers.
I worked closely with friends in show business, and I noticed that they were often happy with the work they were doing because they occupied a privileged place in the theater, but the people in the audience weren’t enjoying that same level of satisfaction. So I put myself in the shoes of the spectator, and I realized that I was frustrated. I had to concentrate to connect the sound with what my eyes were seeing, a process that spoiled the artistic experience of the show for me.
Unlike a technician, a spectator is looking for enjoyment, spontaneity, sensation and realism. He doesn’t try to understand if the treble is clean or if the phase is coherent, and that’s what made me gradually think about refocusing on sound and image, to merge them. Another factor which pushed me on is the enlargement of stage-fronts to provide more room for set and lights, which in turn relegates the sound to the sides and disassociates sound and image.
Jean-Claude Casadesus and the Orchestre National de Lille in fusion with the L-ISA system
SLU: We try to fight this outward drift by using small central reinforcements…
Christian Heil: We try to do that but it doesn’t work very well. So I told myself that we had to try to enter the multidimensional and hyperrealistic realm, correcting the historical error of putting speakers on the left and right, while the people are in the center.
SLU: At first, we used to hang a central cluster…
Christian Heil: It was a very good idea! Then we had to fall into the illusion of stereo, while we never stopped using dual mono. The solution to try and change the game could only come from a respected, innovative and well-established manufacturer. But it’s not going to be easy. We’re not going up against other speaker manufacturers – instead, we’ll be opposed by lighting designers and scenographers who won’t want arrays of speakers in the field of vision.
I’ll tell you a story. I was invited to the London concert of a world-famous artist. The show starts and I can’t see him. The huge video wall projects psychedelic images. It ends up showing him, very small and at the center of the stage. Is this really doing justice to the artist, who was returning to the stage after a long absence?
A review of how L-ISA works. The “spatialized” zone offers any listener within it an immersion in the mix with a precise correlation between the location of the source on the stage and the amplified sound it generates.
Here is what a standard left/right would provide in the Lille Arena. The light green area represents the zone where the stereo image and the phase are optimal, the dark green area is where the listener is covered in dual mono, interfering also with the out-fills and, finally, the yellow area is where only the out-fills are heard. The portion where the audience receives a stereo signal is no more than 8%.
The same prediction, but with the L-ISA system. The dark green here is the interfering zone between L-ISA and K2 side hangs. 26% of the public receives a signal in phase and with a spatialized image.
The experience of a concert is not “sonic” enough anymore. L-ISA is a gamble that needs the support of sound engineers, but the ones who undertake this choice are still rare. François Gabert, Stéphane Evrard and the entire ONL team took the plunge – let’s call that a perfect alignment of planets.
SLU: When did L-ISA take shape?
Christian Heil: We started in 2012 with Sherif El Barbari – our field man, who specified the project and participated actively in the development – and with Guillaume le Nost, who took charge of the development and built the necessary team for that. For a few years we worked in the shadows of a laboratory, doing algorithmic tests and compatibility tests to create sound designs.
We had the systems, but switching from left/right to multichannel meant changing their size. That said, we have the necessary models, between Kara, Kiva II and Syva. We should have had Kiva II for today’s production, but unfortunately it is too recent a product, and we couldn’t find the number of enclosures necessary in time.
François Gabert’s FoH, with his Lawo and his pair of PCM96s. At the top, the seven arrays of the L-ISA system, extended beyond the stage.
SLU: I must say that in the extended version, with seven arrays, it really starts to perform! How many are needed for a typical deployment?
Christian Heil: L-ISA has two parts. The first, called the Scene system, uses five or more arrays to cover the width of the performance area where the musicians are. The second, called the Extension zone, offers a wider panorama in which we will put reverberations, ambiance, some synths and choruses. A kind of outer panorama. It’s not necessary for the Scene and Extension systems to have the same density.
If you were touring with a big rock band in arenas like the AccorHotels in Paris or the O2 in London, it wouldn’t be unthinkable to hang K2, which opens very wide, naturally has more contour and would immediately reassure the sound engineers, who would be in their comfort zone. The major disadvantage is that, instead of hanging two big classic arrays, we would put five slightly shorter ones. Add the Extension and the budget will no longer be feasible. We work according to a scale ratio and a number of specific components, whether they are K2 or Kiva II.
L-ISA. Lots of small enclosures or fewer large ones…
SLU: Agreed, as far as the drivers are concerned, but for the low frequency transducers and the possibility of some models, like K2, to be used in full range, the game changes with Kiva…
Christian Heil: Absolutely. Tonight, for example, this is a configuration where the need for classical music contour is not very high, but even in case of more demanding music, the amount of equipment would not drastically change. To better understand, let’s go back a bit to basic acoustics. When you put the hundred or so 15-inch or 18-inch membranes of a traditional system into an audience, there’s a little chaos, sort of like what was done before the V-DOSC when you multiplied the number of boxes.
Suspended bass sources combine only in the plane that bisects the line between them, and when you get outside of that, you have problems. When you add some subs, which are occasionally arranged frontally for a more distributed result, you don’t gain much energy because of the losses in efficiency due to the linear configuration.
Eight KS28 flown centrally, cardioid and endfire. It may seem like little, but their placement, their impact and their incredible sensitivity make this number more than enough, especially for classical music.
The concept of L-ISA specifies that all of the bass and the infra be located in the center, because everyone knows that if we could place all sources of bass in the same place, within a distance of one half-wavelength, we would have the punch throughout the whole room. Ideally, even if it’s not going to please the lighting people, hanging the subs in a central point, when technically possible, is good for the sound. When this isn’t possible, one solution may be to decouple the sources to avoid interference, but for that you have to convince sound engineers who naturally prefer their comfort zone.
Madje Malki, the hyperrealist immersion adventurer and Christian Heil’s long-time accomplice!
Even a friend and adventurer like Madje, who used L-ISA for a long Renaud tour (a well known and highly appreciated French pop singer – ed.), sometimes feels the need to return to a more conventional mix. Finally, it seems to me that, in the low end of the spectrum, we’re reaching overkill. A well-known heavy metal band used 64 subs at the AccorHotels Arena recently. I think it works, in a bit of a….. chaotic way. (he laughs).
SLU: Fortunately, otherwise it would be intolerable! If I understand you correctly, you want to entrust the bass and the infrabass to a single central point of emission, and the rest of the spectrum would go to L-ISA arrays.
Christian Heil: Everything below 100 Hz can be grouped in one place, which allows you to use smaller arrays. That’s why there is no K2 in the central array. We connect everything in the center with subs, which also work as bass cabinets.
SLU: Do they have a specific preset?
Christian Heil: They have to go up to 100 Hz. We did some outdoor tests, and even if I take the outermost array in Kara in relation to a single source point of bass and infra, it still works better than if I hang K2 and I add some subs in the center, because they interfere. This, of course, can’t be extended infinitely because of the relative distance between subs and heads. It would create problems of delay and level. So I’m not saying that in a stadium, with a central system and a stagefront of 70 meters, we would place Kara 30 meters from the bass point, but in many other places, we would have a better result than with the left/right.
SLU: Kara is therefore the reference enclosure for L-ISA. A single 3” driver is not a problem?
Christian Heil: The number of drivers doesn’t matter, it’s a line-source system, we use as many enclosures as it takes.
SLU: How does one determine the number of enclosures with L-ISA, exactly?
Christian Heil: We begin the L-ISA design from the base, the left/right. Here in Lille we looked at the 2016 design, the SPL mapping, and we proposed the “same thing ” but with another system. We provide the same energy, distributed in the room.
An indiscreet view of a place long kept secret, the famous auditorium of Marcoussis, where the trio of Heil, El Barbari & Le Nost spent long days in full immersion. Many stacks of six Kara each and four SB28 have served the cause for many years…
L-ISA is providing the same distributed energy as a traditional system. But better.
SLU: So, I’ll ask the question to the designer and engineer: is the 60-120 Hz octave reproduced by a system of small speakers equivalent in impact and in qualitative feeling to that delivered by a system with an equal emissive surface but using, for example, 12” cones?
Christian Heil: We asked ourselves this question, too. The answer is somewhere between yes and no. I think that, first and foremost, it’s about mixing references, but at the same time I’m not a mixing engineer, and if Madje were here, he might not agree (he laughs!). With everything between 60 Hz and 100 Hz, I will always prefer the reproduction from a 15-inch and even an 18-inch transducer, which has less distortion. Once you go above 100 Hz, I don’t see the difference anymore.
Now look at the problem in reverse: do I not prefer to divide the sound energy in the 80 to 120 Hz band over a series of 8-inch transducers, rather than concentrating all that energy on two 15-inch speakers? This time, the answer is not so clear. If I put a single signal on an 8″ membrane and a 15″ membrane, I would prefer the 15″.
But it’s not the same thing at all with music. When I combine a lot of different signals and I drive them all into a 15″ membrane, their combination is not ideal; I prefer more and smaller membranes. When we talk about Madje and Renaud (Madje and the sound company Potar Hurlant have used L-ISA on a long Renaud tour– ed.), as wel as all good pop and rock mixers, they all tend to bring their mix back to the center.
Renaud’s stop in Paris at the Zenith. Six KS28 in a cardioid configuration and a central array of 14 Kara.
SLU: Which has always provided the punch…
Christian Heil : Exactly, except that, if we put kick drum, bass, in short, the fundamental elements in few Kara and only in the center, the system will suffer more than, for example, in a line of K2. We must learn to expand and better exploit the number of enclosures in the air, which the classical sound engineers are doing very well. That said, if Madje doesn’t agree, I’m sure he’d be happy to express his opinion here!
SLU: He’s welcome whenever he wants and he knows it (Madje, if you’re listening…). Is that why you prefer L-ISA for pop shows that are a little more “calm”?
Christian Heil: Certainly, it’s more appropriate for a style of music that takes advantage of spatialization and not so much of power in the way that we have just mentioned. I’m thinking of Jean-Michel Jarre, for example. The very nature of his music would work excellently with L-ISA.
SLU: And could benefit from automation of the movements…
Christian Heil: Of course, there are plenty of possibilities with the movements that, in some music, could add a lot.
Which enclosure for L-ISA?
SLU: Don’t you think that the current limit of L-ISA is Kara, because of its rather limited impact in the bass, its dynamics and, especially, its dispersion, which at 110° doesn’t have the appropriate coverage for your multichannel technology… in other words, wouldn’t it be better to have a specific enclosure for L-ISA in order to help it succeed?
At least 140° of dispersion from Syva up to above 10 kHz. Just what is needed for L-ISA and for a lead vocal amplified only from the center array to reach the entire audience.
Christian Heil: Of course Ludo, but all in good time. The answer is clear. If L-ISA and multidimensional systems in general catch on, we will have to reinvent sound systems to make them lighter, quicker to install and with wider coverage.
If we meet with success beyond the enthusiasm of the public – namely the willingness of the productions to take the leap –we’ll likely have to go back to the drawing board. I think now it’s still premature. In any case, it’s the sound companies who will demand systems from us that are designed specifically for multidimensional deployment.
SLU: There is already Syva…
Christian Heil: Yes, and it’s an excellent enclosure for L-ISA. One could easily amplify a classical or jazz ensemble in a room of 1,500 seats with this Syva. (This was actually a premonition of Christian Heil. Alain Français a highly respected live sound engineer did it at the Théâtre des Champs Elysées in October – ed.)
SLU: With its very wide dispersion, it is the only one in the L-Acoustics catalog that perfectly corresponds to the L-ISA principle, which requires that each group of the frontal system optimally cover a common area representing more than 75% of the audience area.
Christian Heil: This enclosure was a gamble and the results are very good, in residential applications and in live. Its nominal horizontal dispersion is 140° and effectively guarantees excellent coverage, which is the key to L-ISA.
The software side of L-ISA
SLU: Where are you in the development of the IT tools to manage L-ISA?
Christian Heil: We are advancing in parallel. Today, the latest generation of Soundvision is able to qualitatively analyze a multidimensional design because we know that it is different and necessarily complex. We have been doing left/right for 40 or 50 years without asking ourselves very often the question of where it overlaps, how far the central stereo – which is actually closer to being a dual mono – goes.. In fact, no one knows what the percentage is of each category.
A view of the L-ISA gauge. The number of criteria is such that it would be difficult or impossible to make it “stick to the walls”. The GUI of this gauge is still provisional.
SLU: Yes, you can see it with Soundvision.
Christian Heil: Right, we now have a layer in Soundvision that is practically a certification of our own designs, whether they are left/right or multidimensional, and this by means of a score.
This new layer is the result of various criteria identified as the percentage of the audience covered, the one to which all signals converge. There is an SPL distribution criterion. We also check – and this is new – the temporal impact related to different acoustic paths, depending on where the listener is positioned in the room. We’ve gotten used to it, but in dual mono, as in stereo, we live with comb filtering and the sonic pollution of the second source. We also have a criterion that is related to the resolution of the sources: the ability of a spectator to recognize and separate the sources he hears.
It’s a kind of spatial resolution, like a pixel in an image. We will also look at the angular deviation that exists between the real source and the sound source. A score is given to the horizontal and vertical deflection. Due to the placement of the arrays, often where it errs the most is in the vertical deflection, which pushes us to negotiate the lowest possible hangs. But this is difficult because a show combines sound, lights, images and scenery, and everything must coexist for the entire audience. All of these aggregate scores provide a final score. No more lying to ourselves… we know exactly and objectively where we stand from a qualitative point of view.
Christian Heil with, on the right, Stéphane Evrard, the Technical Director of the ONL.
SLU: L-ISA demands real know-how from the operator…
Christian Heil: Yes, but I’m doing what I used to do with the V-DOSC twenty years ago. L-ISA works on principles that we establish almost like school rules – rules made to be outdated later on. The technicians who use this system will go outside of the box and will invent countless other uses. The Puy du Fou, with its circular stage, and other theme parks loved the possibilities offered by L-ISA.
L-ISA, work in progress ?
SLU: Will the L-ISA processor algorithms evolve further?
Christian Heil: Guillaume le Nost, who develops it, and Sherif El Barbari, who utilizes it, have spent nearly three years working on the way audio is manipulated in the processor.
Sherif El Barbari assists François Gabert and answers all his questions about L-ISA, which he knows like the back of his measurement microphones.
Sherif, who, much like you, is extremely attentive to details, often brings me suggestions for improvement, but micro-details, especially compared to what we are used to hearing from good old left/right, whose interferences are inherent to the very principle of the two arrays. But the answer is yes, it will certainly evolve. If you had seen the first preset that I created for the V-DOSC at a time when I didn’t know the particularities inherent to shows, it was…
SLU: Not good? (Laughter)
Christian Heil: There have been subsequent generations of presets – as I recall, there have been seven – and now we understand what needs to be done.
SLU: How do you harmonize what the hanged and stacked enclosures reproduce?
Christian Heil: The lower ones play a mono reduction. This is logical, because if you are at the end of the stage and very close to it, you will hear only your lip-fill enclosure. If I don’t play a mono reduction and the soprano is at the opposite end of the stage, you will miss her song. With a mono lip-fill, you will hear it. They say it is possible that in the future, and depending on the circumstances, it will be composed of mono and non-mono mixes. We are working on this aspect, and maybe we will go to stereo
SLU: What should you do for the sides, where a lot of people tend to be positioned? At the moment there is K2 here in Lille, and even on the Renaud tour. Could you not attempt to create even a reduced effect of spatialization?
Christian Heil: We thought about it; we tried a certain form of duplication but, for the moment, we haven’t found the right solution because the pollution that it causes far outweighs providing quality sound to more people. Returning to L-ISA in general, we bring substantial improvements over what was done before, but we can’t remove some defects.
The need to see the stage and the video screens for the spectators in the stands, and a certain obsession with the “speakers being ugly” on the part of the scenographers, force the systems to be moved far out to the sides and, in the case of L-ISA, to be hung very high – a little too high. A difficult problem to solve.
Verticality, that is, the distance from the audience, will always be a problem. A musical where the speakers are placed very high doesn’t work as well as it should with L-ISA, but no worse than with current systems. We are simply used to it and, essentially, we will always find more defects in a new system than in the one we know.
Syva during one of its first outings, in the expert hands of Alain Français, just a year ago in the heart of the Louvre in Paris.
SLU: So we are almost at the end of the development phase of L-ISA…
Christian Heil: No, that would be a lie, but we are pretty damned far along. We started in 2012 and we didn’t just do theory, we put our ideas into practice in the field – so L-ISA is quite ready to be marketed. The second phase, which will start in parallel, is its adoption by sound engineers.
SLU: Can we say that L-ISA is the latest news from and the future of L-Acoustics?
Christian Heil: The latest from the audio system manufacturer L-Acoustics is Syva. First and foremost, we are introducing a different branch in the group that deals with sound design, which focuses on what the product does when it is put into a situation and not just what it delivers in terms of coverage or SPL. I would say that L-Acoustics is more and more interested in the application and the implementation of its products.
L-ISA is at the head of what we would like to do in multi-channel FoH sound design that’s easy to deploy. In this respect, the merit of this L-ISA installation in Lille goes to Fred Bailly and Sherif. My contribution was basically the #1 and #7 boxes, the ones that extend it (he laughs!). You have to cheat – stretch the orchestra to fill a room this big. The L-ISA Processor knows how to generate 32 outputs, of which six are pre-assigned to downmixes.
And the secret of L-ISA is…
One of the flaws pointed out by Christian and visualized on this rendering, the vertical localization, namely the gap between the stage and the coverage. Note that, for many seats facing the stage, it reaches and exceeds 60°, which is too similar to a shower, and that the lip-fills provide only imperfect coverage since they don’t integrate the particular distribution of L-ISA.
SLU: What distance should you leave between each cluster? It is four meters here, it seems to me…
Christian Heil: There are four meters for a question of fluidity. There could be a little more since we are operating over quite large distances. Beyond a certain distance, the sound does not couple well between one cluster and another and especially if, for example, it is necessary to follow the movement of an artist with a tracker, you lose fluidity in the transition between the clusters and it becomes a “magnetic” effect of jumping from one to the other. It also depends on the dispersion angle of the speaker enclosures but, anyway, it is purely for acoustic and design reasons.
Some small flaws also in the horizontal localization. Without a doubt, a speaker enclosure with a dispersion that opens more laterally, positioned a few meters farther back (if its rear attenuation allows it), could easily solve this problem and partly that of the lip-fills…
SLU: L-ISA will still require a lot of education to explain the new fundamentals…
Christian Heil: That’s right! We are re-shuffling the cards. I was recently told: “but, you always said that one shouldn’t put two line arrays within seven meters of each other!”. That’s true, but specifically when you have the same signal in both, with the whole band. L-ISA works in separation mode, the same signal is never in two adjacent speakers… (I interrupt him)
SLU: Yet, we can open the same signal up onto several arrays via the controller!
Christian Heil: Indeed, there is a mechanism in the algorithm that attempts to minimize interference issues and corrects the tone to ensure that the two systems sound like one, which is otherwise not the case. It is also necessary to do the off-axis coloration and the phase rotation to avoid interference. We spent years developing it with sharp people who listened and split hairs. The algorithm is good. What could be improved even here today is the vertical distance and therefore the realism for the front rows.
The L-ISA plugin, which can be incorporated into VST or AAX environments and operates dynamically in the project and with the automation of the digital editor. This plugin then delivers its instructions to the L-ISA Processor via a simple network cable.
SLU: I agree completely. The coupling and the sound in the first rows is not optimal. It is better to be further back and in the coverage of L-ISA alone.
Christian Heil: Whoever invents near-fills that work and are effective for the first five rows, I’ll take my hat off to him. I attend many shows in London, where I live, but very few shows where the near field is convincing.
SLU: I imagine that integrating part of L-ISA into DiGiCo consoles will help encourage people to adopt it…
Christian Heil: Of course. Sherif and Guillaume have worked to make this agreement with DiGiCo, and this makes the system even easier and more convenient to implement. L-ISA is an adventure that began five years ago and whose maturity will interest productions. I am not convinced that the pace will pick up all at once. It is necessary for people who have confidence in me and in the brand, and those who have power, to take the first step… people, for example, like Stéphane Plisson in France but also the sound engineer of Adèle or of Radiohead.
From left to right: Christian Heil, François Gabert, Erdo Groot and François Bou, the general manager of the ONL. The concert has just ended and everyone is sincerely delighted.
Contemplations as Conclusions
Let us first render unto Caesar the things that are François Gabert’s. The most perfect sound reinforcement system is not much use if one pushes it into the bizarre. Fortunately, this man is as serene and balanced as his mix. We feasted for an hour, savoring in great detail the work of Jean-Claude Casadesus and the Orchestre National de Lille. Also, hats off to the architects who designed the “showbiz” version of the Pierre Mauroy stadium. The versatility of this room is a staggering reality. Especially regarding the acoustics. The capacity, the accessibility, the rigging possibilities, but especially the solid acoustic architecture make it a remarkable venue, an Arena with a capital ‘A’.
With its closed roof with multiple rigging points, its floor as smooth as a line array waveguide, and its wonderful acoustics, this half stadium is THE answer to the needs for show venues. Remember that a resident football team plays, at most, only 25 to 30 matches at home, the rest of the time…
What is L-ISA? To put it simply, I would say that it is the best compromise possible in a field that is all compromises. L-ISA is the most economically viable and acoustically efficient way to obtain an immersive, coherent and spectacular sound front in terms of coverage area, frequency response, phase, dynamics and SPL. The idea and the technology behind it are not new, but their integration into a powerful processor, driven by a very sophisticated algorithm and controlled by an object controller, are quite new. When a juggernaut like L-Acoustics gets involved in a project, it’s never taken lightly, and L-ISA is no exception. Several questions then arise.
Christian Heil, here with Fred Bailly, responds to numerous requests from the technicians present, and prepares for the performance of the star system. It’s not enough to have given the world the V-DOSC, one must assume responsibility for it ;0)
Is L-ISA good for everything? Theoretically, yes. Offering a vast sound field and precise localization of sources to more than half of the audience, and in some cases even more, it is good for all applications and musical styles. In addition, the simple and remotely controllable management of objects, which can also be automated, opens up an infinity of creative possibilities.
Faced with soloists that were too bright, too forward in the mix and probably too “amplified” sounding, François Gabert, for example, made the choice during the concert to move them back in space, a simple way to make them blend more into the mix and give them more authenticity. L-ISA is a key that technicians, but also artists, can appropriate. Let’s not forget that it was through the influence of Pink Floyd that quadraphonic sound existed on a large scale.
Kiva II, an enclosure that can be found often in L-ISA deployments. Passive, 16 ohms, 138 dB SPL max, all in a 14 kg cabinet and with 100° dispersion.
Can L-ISA also excel in styles that are demanding in terms of speakers and SPL? Once again the answer is “yes”, taking advantage of the enclosures already in the catalog, but it would probably be even easier with a dedicated model: a speaker enclosure with specific forms and specific functions able to reproduce, with modern power and dynamics, the spectrum from 100 Hz to 16 kHz, with a very wide dispersion and maybe adjustable waveguides, a speaker able to deliver more SPL but with a limited number of boxes, in order to facilitate its visual integration.
Finally, it would have to be an enclosure with a cardioid dispersion to allow it to be placed vertically, without the risk of impacting the stage, which would offer a wider L-ISA coverage and which would also serve the front rows. A punchy and modern enclosure that would help sound engineers get away from such a monophonic vision. What is true for the high end is also true for the low end of the spectrum. For the lows, it would ideally be a very powerful box, combining bass and sub reinforcement, able to fully reproduce the first two octaves with a native cardioid directivity, in order to concentrate a factory of bass in a small and central space.
The full-range mapping of the L-ISA deployment in Lille. A maximum SPL of 103 dBA and a minimum of 97 dBA with, of course, all the speaker enclosures operating. There are people there, you still have to feed them…
Is L-ISA creative and easy to use? The answer to the first part of the question is clearly “yes” but, even more, it is also a mixing tool in its own right that has its place in a console and not just relegated to its screen and mouse. Its integration into DiGiCo consoles will be very beneficial and should be emulated. Simple to use… maybe not if you are on the design side.
The need, for example, to concentrate the bass cabinets in a single point makes it difficult to deploy outdoors or anywhere there are problems with rigging point weight limits. It will also take some time for the sound engineer to get a feel for the set of speakers and their layout to open their mix and, especially, to understand that we must use more enclosures to get the pressure that any show requires.
Does L-ISA sound good? Here the answer is once again “yes”. The strategies deployed within the processor make it possible to combine the same signals as constructively as possible in two or more spaced lines. It isn’t obvious on paper. Yet it works much better than what is currently given by two main line sources, which already don’t love each other very much, and to which we add the down-fills, out-fills, lip-fills, front-fills, the flown bass cabinets and the subs on the floor. Let’s be honest. We are used to it, but it is very often “interferenceland”… So yes, sometimes we perceive some artifacts, but the whole is infinitely more faithful and generous in coverage and audio quality than the usual left/right.
A 4000-seat amphitheater, the perfect place for L-ISA. Here the left/right version with 12 K2s, providing a comfort zone to 25% of the audience.
The same shed in Santa Barbara, this time with an L-ISA deployment of five Stage arrays of 12 Kara each and two Extended arrays with eight Kara each. The comfort zone reaches 87% with a true spatialization.
Finally, is L-ISA a good answer to the new standards for levels? Without hesitation, yes. By the fullness of its performance at reasonable pressures, and by playing away from the audience with a single group of point-source speakers the part of the spectrum that has just appeared on the screens of analyzers henceforth touchy to dBC, L-ISA will feast the public, as well as the public authorities. In fact, the Requiem at its magnificent fortissimi reached only 98 dBA and just above that in C-weighted. At 4 dB from the limiters. Another advantage that makes life easier for the mixer is that the output at FoH is not boosted +6 dB as usual, since heads as well as subs distribute the SPL better.
In fact, we could start asking ourselves a simple question. What if left/right is a thing of the past?
JJean-Claude Casadesus and the Lille National Orchestra.
Perhaps you missed parts 1 and 2 of our file on L-ISA, find them here: