Show Scene: More On The Line Array Front
An intrepid U.K. correspondent goes in-depth on the latest

By Andy Wood

QSC’s Barry Farrell and the new ISIS.

There is perhaps no better way in the world to start an argument within the professional audio industry than to pit European audio technology against that of the U.S. From the European perspective, of course, every homegrown concept has been taken by the U.S., which in turn claims it as its own. The U.S., on the other hand, often proclaims that it is the originator of the concept, or at the very least, expanded it to full potential.

No, don’t get drawn into that one ­ particularly if the topic is line array development. If you received a dollar for every time Olson’s classic text Acoustical Engineering is quoted, yes, you’d be rich. And what of the “Wall of Sound” of Grateful Dead fame? But then again, what about the landmark work of Dr. Christian Heil of L-ACOUSTICS? The whole subject is a minefield.

As it is, the line array scuttle has not only been around since day one, but has most certainly picked up in intensity with the proliferation of modern-day concert line arrays (led most certainly by Dr. Heil) now dominating the marketplace. And let the line array “wars” continue ­ it certainly beats other types of much more serious conflict that come to mind!

NEXT GENERATION

The recent Professional Sound and Light Association (PLASA) Expo in London proved to be a highly interesting exercise for those with a penchant for line array. Hidden away among the high-rise VIP bars, booth babes and (heaven forbid) lighting and D.J. technology, were the next big Euro wave of line array offerings. And this stuff, just like Jean Luc Picard, is Next Generation.

PLASA saw the introduction of no less than six new line array models, plus a good second look (after the Frankfurt MusilkMesse and NSCA Expo) of four more recent contenders. Two of these ­ EAW Digital Steerable Array (DSA) and QSC ISIS ­ originate from the U.S. From Canada, Adamson weighed in, while the rest came from Europe, including one that uses ribbon drivers.

It’s an early sighting of Adamson’s new Spektrix.

Hold on a minute ­ QSC? Yes indeed, direct from beta testing on a Bob Dylan tour (no less) comes the ISIS Series WideLine. This full-range (55 Hz to 18 kHz per enclosure) three-way/active two-way box was given quite a low-key introduction, to the extent that attendees were treated to cartoon presentation about QSC-ontrol.net while what they really wanted was information on the stacked boxes to the left and right of the video screen. According to QSC sources, the original idea was to produce a three-piece stack that would sit on the ISIS 215 powered subwoofer, yet lo and behold, some bright spark decided to fly a few to see what happened. Voila! It’s a line array, and perhaps more importantly, QSC’s entry into this market sector.

The interesting issue here is the rather considerable 140-degree horizontal dispersion pattern, the widest, says QSC, of any line array currently available, with the vertical dependent on the number of elements used. In addition, the system also offers selectable mid-range frequency shading and is said to direct the mid-bass toward the center of the hall for “more coherent pattern control and better intelligibility.”

Weight has also been addressed, at 70 pounds (32 kg) per box, while the audio aspect is handled by dual 350-watt, 16-ohm, 10-inch low-frequency and a 1.4-inch-exit, 80-watt, 16-ohm neodymium compression driver mounted on a proprietary multiple aperture diffraction-slot waveguide.

Adamson unveiled Spektrix, new compact system based upon the success of the Y-Axis, a rig that has enjoyed a growing reputation on both sides of the Atlantic. Again, weight reduction has been a primary concern, with the trapezoidal Baltic birch boxes weighing in about the same as the QSC.

But there, effectively, the similarities end, for the Adam-son utilizes a proprietary

1.4-inch-exit 80-watt, 8-ohm neodymium compression driver mounted on a proprietary “wave-shaping” drive module and a pair of proprietary neodymium 8-inch Kevlar drivers.

These components are used in conjunction, via a custom band-pass network and direct-radiated low-frequency section, to form a bi-amped three-way cabinet operating at 80 Hz to 18 kHz. Horizontal dispersion is 120 degrees, with 5-degree vertical dispersion. Other boxes in the pipeline include a dedicated Spektrix sub, and 20-degree vertical downfill.

CONVERTED SKEPTIC

Let’s turn focus to the new European models, starting with one of the prolific players, Martin Audio. While R & D departments the world over burned the midnight oil to create versions of the line array concept, Martin waited. Indeed, some argued that the firm had left the gate too late by the time the W8L hit the streets, but as Chief Designer Bill Webb converted from a line array skeptic to a confirmed supporter, the models began and now keep on coming.

Bill Webb with Martin’s new Mini.

The latest culmination is the W8LM Mini, which, according to Mr Webb, might be the firm’s last foray into line array market. (We certainly won’t hold him to this.) Although Webb concedes (unlike some line array evangelists) that the principal does not provide the best solution to all sound design requirements, he does admit that a professional loudspeaker firm needs to have line arrays in its portfolio, much in the same way that a car manufacturer should feature a hatchback in its brochure. It’s demand and supply, as opposed to the creation of demand via hype. But that’s another argument best left alone...

The W8LM Mini fills a vital role, in that it is a three-way, active/passive designed for use in areas where ‘the line array principle is demanded but space is at a premium. (The telling term there is “demanded”.) Here we have a full-bandwidth (60 Hz to 18 kHz) system using a proprietary technology to produce a constant directivity, horizontal pattern control of more than 120 degrees (700 Hz to18 kHz).

It’s an airborne AERO system, with subs, from D.A.S.

Designed for flying or ground stacking, the 12W box is also compatible with a new WLX Hybrid sub. Weight is quoted as 53 pounds (24 kg), and with all Martin designs, horn loading is the order of the day. In the case of the W8LM Mini, the low frequency 8-inch is a reflex-loaded direct generator, with the mid-frequency 8-inch neodymium driver is front-horn loaded, and rear reflex loaded. A pair of 1-inch horn-loaded compression drivers look after the highs. As a casual observer, it’s interesting to see the bigger picture. Here we have two firms on one side of the Atlantic, identifying that smaller, lighter line array products are required, and in Europe, they get smaller still.

Practical reasons for this, in my view: it goes more to smaller venue and production size in Europe. The incredible long-throw and high-SPL systems demanded by massive stadiums and arenas in the U.S. are simply not nearly as prevalent “across the pond”, so bigger is overkill to the majority of shows and venues here.

And while some larger requirements do exist in Europe, the average audio appetite is smaller. The European manufacturers have therefore adapted and thus employed the line array principal to fit the mold via a proliferation of smaller, lighter systems.

ACOUSTIC LENS

Spanish manufacturer D.A.S. Audio, which introduced the D.A.S. AERO CA 28/ CA215 line array at the show, gave a further example of this point. The CA28 itself is a full range (80 Hz to 20 kHz), twin 8-inch neodymium loaded box that also utilizes a D.A.S. M10N 1.5-inch-exit, 3-inch voice coil compression driver.

However, the DAS doesn’t go for the whole wide dispersion play, as its proprietary SERPIS wave generator gives a 90-degree by 6 -degree output. Low-frequency energy (35 Hz to 300 Hz) is provided by a pair of 15-inch woofers in the CA 215, and the whole lot can be flown as a three-way system.

PLASA also gave visitors one of the first looks at the Qube-210 line array, which, as a joint venture between Italian manufacturer FBT and Renkus-Heinz, also supplies indications of future developments. This is a two-way passive line array speaker with two 10-inch neodymium woofers and two 1-inch neodymium drivers.

The new Alcons array that generated interest with its ribbon drivers.

Naturally, proprietary technology is also at work, and here it is: “the Isophasic Plane Wave Generator”, which employs a “true acoustic lens’” in the horn section. Minimum hang is six speakers, but with the cabinets less than 24 inches (60 cm), wide, we’re looking compact again. Interestingly, Qube quote a horizontal dispersion of 150 degrees, which would seemingly be in conflict with QSC’s claim, and with an identical weight of 70 pounds per box, it should be prove interesting to do an A-B between the two systems. If nothing else it shows that, as with the situation with the Nexo and Outline boxes, minds do seemingly think alike irrespective of regional influences.

Which leads us neatly into the “new ground” as it were, with Dutch firm Alcons Audio and German firm HK Audio, both introducing new systems that seem to break into new areas of what, arguably, has become a standardized format.

WRAP IT WITH RIBBON

The story from Alcons is interesting, as it is based very much in the history of ribbon driver manufacturer Stage Accompany, with whom many of the Alcons engineers cut their audio teeth. Led by Tom Back, the team has always believed in the concept of using ribbon technology with a line array principal system.

Indeed, they have not been on their own, with almost every manufacturer understanding the concept of the natural cylindrical wave front created by a flat-diaphragm tweeter (or ribbon driver). The problem has been creating such a tweeter that would happily create the high SPL required for a long -throw array.

HK Audio’s Cohedra. Two models are available.

With the RBN601, a 6-inch ribbon transducer, Alcons believes it has created such a beast, and with over 15 years experience, plus many OEM models to their credit in past lives, it’s an intriguing project. “Our RBN601 is the only pro-ribbon driver with ‘real-90-degree’ dispersion,” Back told me, adding that this refers to a horizontal dispersion of 90 degrees all the way to 20 kHz, whereas other pro-ribbon drivers have a 90-degree point up to 8.5 kHz. As such, he feels it’s a very good building block for line arrays, in Alcons’ case, the LR-16, which twins the ribbon with a pair of 8-inch drivers.

Interest in this product was high, with a steady stream of manufacturers taking a chance to get up close to the boxes for the first time. But what was interesting to see was the waveguide in front of the ribbon, which comprises a series of eight horizontal slats with differing horn-type apertures down the transducer.

According to Back, the flat isophasic wavefront generated by a ribbon transducer doesn’t allow J-shaped array curving. Thus for the required curved isophasic wavefront, there was still need to develop a special waveguide configuration, though the ribbon’s cylindrical wavefront provides advantages in the design.

In real terms, the LR-16 is still in it’s early days, but given the reports from it’s first outing in Berlin, and the reaction of the other manufacturers, Alcons may have created something of a breakthrough here. At least it should give the other R & D departments something to consider, and one imagines that a shoot-out between Alcons and the U.S.-born SPL system (for whom Stage Accompany once OEM’d ribbons) could prove interesting.

LESS THAN TRENDY

Let’s move along to the final line array to be covered, from HK Audio. It’s a system, like Alcons, that promises to offer a little more. Based in St. Wendel, next to the French border, HK has been a successful but perhaps less-than-trendy manufacturer. Best known for its solid R-series and T-series cabinets, which have been championed by Deep Purple, the HK Coherent Dynamic Response Array, or more snappily titled “Cohedra”, entered the market with guns blazing.

Nothing shy or retiring about HK. In a voluminous document, the company’s head of acoustics, Thomas Adt, dissects many well-know line array designs, and interestingly, argues their inadequacies and strengths. In summary, he concludes that some portions of some line array designs work as intended, while many others must be improved upon. You may disagree with Adt’s assessments, but it makes for interesting reading, nonetheless.

So, what does HK provide for your Euros (or dollars)? A pair of 10-inch drivers in a bass reflex chassis for low frequencies, with the mids handled by a pair of 8-inch neodymium speakers coupled coherently (horizontal ­ vertical) up to 800 Hz, with a compression chamber.

In addition, a B & C Speakers DE900 1.4-inch compression driver uses an (patent applied for, naturally) acoustic lens and constant directivity horn. This design, claims HK, creates no Doppler effects via interaction with the mids, and no coherent wave created at the slit of the lens itself. A proprietary Cohedra controller incorporates phase correction by the means of FIR filters, as well as limiting.

Two 500-watt, 8-ohm enclosures (models CDR 208C and CDR 208S) can be utilized to minimize gaps between cabinets. Toss in an 80-degree by 5-degree dispersion and weight of 66 pounds (30kg) per flown box, and off you go. Third generation? Maybe not. But worthy of further examination? Maybe so.

So, what can we learn from these PLASA releases? Most importantly, we’re seeing how some companies are trying to beat the “me too” syndrome by incorporating new developments in well-established theory, and are also fine-tuning the principal in an effort to improve the genre.

This, of course, has taken time, but as any tortoise will tell you, the hare is there to be beaten. Then again, the hare might just own a Harley... If so, it’s going to be a close finish.

Andy Wood is a veteran audio journalist based in the U.K., and is editor of Audio Pro magazine. He can be reached at Andy.Wood@mi-pro.com

November 2003 Live Sound International