Birth of the array part seven: So what about the stacks and racks of the future?
The reality is that in 2006 most of the established brands build good products. They all pay homage in one or another ways to the technology that proceeded them. Along the way a few innovations appeared here and there and also clever ways of implementing the established technologies.
Big multi-way, full-range boxes first appeared in the 40s. This one is a multi-cellular horn and a big ‘W’ bin. It was highly efficient… Put 5-watts RMS into it and stand back.
We have seen the Altec A7 in the early picture theatres of the mid-late 50s. Some people were using them for rock shows in the early 70s.
Here is some voice of the theatre boxes used circa 1970. On their own they worked ok when loaded with the correct drivers, crossed at the right frequencies and not driven beyond about their design limitations. None of these early horn-loaded boxes were designed for array configuration. Their primary application was for single source vertical and horizontal dispersion that would be expected in a picture theatre.
The hamburger with the lot from the late 70s: Bigger is better!
As shows got bigger and louder, what they lacked in engineering, they made up with more boxes. It wouldn’t have mattered where you were at this gig, there’s no escape when this lot fires up.
But the times, they were a’changing
This Clair S4 system in the early 80s was a sort of a line array. No one used that word then but you can see that at least the big gig companies were getting the idea that hanging and directing the boxes would put the energy where it was needed. Each box weight 240Kg and they are still big. When the Clare S4 came along the motto was “For good sonic results, put up 1 or 100 boxes”. Maybe an exaggeration perhaps but the principle of minimising multiple arrivals, interference between the boxes and the comb filter lumpy response of arrayed systems was already being experienced and mitigated to some degree where possible. The more you put up, the better it got. This set the style for the next 20 years and most improvements were limited to better rigging, more easily array-able point source boxes and more system processing. Eventually computer simulation, room modelling and array software took the point source box as far as it could go.
The Clair S4 system in action
By the year 2000 it was all about to change in a manner that was as revolutionary as the early big milestones. The new fad was the rediscovering of the line source. Heaps of advantages but it is still a point source box system with the vagaries of interference effect and comb filtering.
It became smaller, lighter and smarter in the late 90s but more was to come
In the 90s the speakers were smaller but the mixing desks got bigger.
And bigger! Anybody who has picked up a Midas mixer will appreciate the man who thought up this alternative use for the humble chain motor hoist
The quiet revolution
Over the last 100 years, getting good audio results at any show has tended to be a lottery with loaded dice. Suitability of venue, budget, available technology, set up time and musical genre all stack up against the likelihood of accurate duplication of the performance to broad masses of people. The lottery can be pushed more in favour of good results with competent and experienced technicians, the right equipment and correct installation. A big pile of speaker boxes thrown up each side of a stage in a hurry is OK for a loud guitar band, but that’s about all.
Two of the enduring enemies are time and cost. Any solution that is lightweight, compact, addresses the previous issues mentioned, and is technically easy to use, will help load the dice in the sound guy’s favour. An array of little boxes that behave like a single element was the dream for any array designer but under the established principles and technologies of the 90s, it seemed impossible. All the available technologies were corrective technologies. They didn’t really address or solve the fundamental physics problem. They were “fixes of preceding fixes”, not a stand-alone viable technology.
There were a couple of manufactures that were trying to deal with the basic dilemma of getting multiple elements to behave as a single sound source across the full spectrum.
The question was who was going to get there first? By early 2000 there were a couple of papers appearing on websites that were skirting around the issue and in 2003, something really new appeared; the tangential array. (A tangent is two lined that touch but not intersect)
Off on a tangent
As it stands today, cruising around the web sites of the industry icons there are a number of variations of pretty much the same approach. With one or two slight exceptions, they are all more or less the same processor tweaked technology drowned in jargon names that attempt to masquerade the reality that they are trying to optimise a non-optimum methodology.
Despite the physics, a well set up modern array can still sound quite good in much of the venue space but you can guarantee that the cheque signer, press and the gig booker will be sitting in line with that phase shift antinode or finger of 4K. What is needed is totally uniform full spectral coverage at the same SPL at all parts of the venue space. Impossible you say? Enter the Tangential array.
The tangential array is truly different
The Tangential array is an innovation that is truly original. It was researched and developed by French company Nexo. It is not overselling this development to say that it ranks up there along with the contributions of Helmholtz, Olson and Schotto. It looks way different to a ‘normal’ speaker box so the first question is “where do the marketing department stop and the real innovation department start?”
The Nexo Geo (pictured left in the image above) is the first tangent array. With patented technology if eliminates the ½ wavelength interference problems experienced by all other arrays.
With the Nexo system, there is not one single development that makes it work; rather there are three patents and a few good experienced based ideas thrown in.
The rigging and alignment fittings on the side are built into the boxes and the whole array is aligned with a laser. With more than .5 of a degree of error, the performance is degraded.
The sub box looks pretty funky as well
The CD 18 Sub Bass is the first really Cardioid pattern bass transducer with a programmable output pattern. Notice the difference in size between the sub and the top box. The Nexo CD 18 programmable cardioid sub is not small, but its output must be heard if it is to be believed. The trick is in its ability to focus energy. You walk around the back of the box and you hear NO SOUND at all emanating from the rear. This is not just a simple case of phase shift to cancel out rear sound, the system does a complete energy refocusing job and thus, the shape of the forward polar pattern can be changed to suit the venue by just pushing buttons.
Modelling and array software and pre-gig preparation is essential to make it work
General and product specific venue modelling software is not new. It has a varied effectiveness and is used by some manufacturers as a sales tool rather than a genuine prediction tool, but the Nexo Geo software is very accurate.
So with all this technology, does it sound good?
Well “sound good” is a subjective judgment so let’s see what can be measured. Here we are back at our two-box array ‘Christmas tree’ (see image below).
Remember the two full range box point source array? The fastest way to degrade a good full range speaker box is to place another one next to it and face them into a closely adjoining field. (Like pretty much every array box on the market). Even opening up the coverage area will still not completely solve the problem. As soon as the waves intersect, you have the comb filters and all the associated phenomena.
And here is the plot of the Geo system array. The white line is the theoretical mathematically perfect model
This polar plot throws up a number of obvious questions. Sceptics would be looking down their noises with crinkly mouths saying “A coincident tangential wave dispersion from a group of single boxes is physically impossible, as the point sources are still independent of each other and software, horn flare rates etc are not going to correct this physical reality”
The polar plot thickens
And they would all be correct. There’s more to this polar plot of course… and that “there’s more” will be the subject in the next issue of Birth of the Array. If you wish to warm up your brain for some heavy tech-talk before nest month’s BOTA, check out the Renkus-Heinz web site (TRAP systems) and the Nexo France web site and find the “Innovation Analysis” and “Application Analysis” papers. Turbo-sound have something to say about this as well. Before long, all the big names will have a take on this. Some have already gone into denial while some are just saying Doh!
The full circle…
So in 2006, the past may have become a history lesson now the Geo is here. Is this so? Well time will tell. But while we’re waiting for next month’s episode of BOTA, there’s one last rule.
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