Technology: Coaxial speakers
his DJ booth monitoring – but with standard 12s and 15s there’s a limit. You can aggregate them, but then you have a line source and other issues kick in straight away.” But coaxial has supporters in some unexpected places. Cedric Montrezor, for example, reports from a certain French manufacturer… “We always use coaxial designs in our point source ranges. We’ve always held that coaxial loudspeakers sound best: the perfect point source simulation is coaxial. Whenever you use a traditional 2-way system, you create some sort of polar lobing effect in the crossover point. Because of the distance between the LF and HF, the lobing prevents wide dispersion and you don’t get good horizontal pattern coverage.” It’s telling that when you
enquire of L-Acoustics about coaxial, you’re directed to M. Montrezor – head of technical support for installation – not the head of technical support for touring, Florent Bernard. It reveals everything that L-Acoustics has achieved through line array: a commanding position in the live touring market worldwide, as pioneers of a much-copied solution for long-throw and high-SPL situations. The range of options is
acknowledged by SSE Audio MD John Penn. “In recent years there has been some resurgence,” he says, “and key brand manufacturers like L-Acoustics have brought out coax products. In a venue where you need better throw and intelligibility above background noise or power over distance, I would always opt for a speaker and compression driver-cum-horn. In nearfield, a coax is much more pleasant: my hi-fi room at home still has a pair of 25-year old Tannoy SRM12Xs powered by a Quad 405, and sounds wonderful.”
THE VISUAL DIMENSION
One front on which coaxial designs remain consistently popular occurs whenever sightlines are important, provided also that distribution is satisfactory and not sacrificed to looks. A good example of the deployment of Tannoy’s VQ Series is Casa De Dios in Guatemala (pictured), a brand new 12,000-seater church installed by Michael Garrison Associates. The original design was for a line array, but VQ was mooted when the church said they wanted the system to be zoneable. “The distributed system of VQ boxes with two delay zones just fits the need a lot
28 l PSNLIVE 2013
The Cribs on stage at the UK’s Friends of Mine Fest (FOMFest) with APG SMX15 monitors: the “classic”coax live application
“We always use coaxial designs in our point source ranges. We’ve always held that coaxial loudspeakers sound best: the perfect point source simulation is coaxial” Cedric Montrezor, L-Acoustics
CONCENTRIC ADULTS Is coaxial perennially confined, then, to some kind of ‘über-hi-fi’ concept, or can it break through into the larger scale sound reinforcement markets now dominated by line array – and, lest we forget,
ever-more compact line array at that?
“Despite Tannoy’s past successes and the many documented advantages of the Dual Concentric driver, the lack of a true high-directivity and high-sensitivity speaker range
tended to relegate Tannoy to mid and small-size solutions,” observes Graham Hendry, VP of application engineering & training for the TC Group. “Inherently based on a high- power evolution of a point-source mid-high transducer, loaded in the patented new horn design Point Source Waveguide, VQ offers high SPL performance, exceptional clarity, low distortion and extremely even coverage. The design is optimised for very good linear response and accurate harmonics, while constant directivity principles are applied throughout the range and offer various dispersion patterns. “For sound reinforcement
speakers, accurate pattern control and directivity are critically important, and the benefits of a point source are being recognised as equally important. We’re currently seeing a point source ‘renaissance’ for a wide spectrum of applications.” The touring version, VQ Live,
better,” says Tannoy’s Graham Hendry. “Comparing the two through computer modelling, the coverage is just so much smoother. With five boxes going across the front, interaction between each device is a lot
less than a line array and its interaction in the horizontal, let alone the vertical, mix. As well as this, it’s a lot more aesthetically unobtrusive, which is ideal for church where the visual aspect is as important as the sound.”
certainly has its fans. Andy Linklater is a FOH engineer for artists including Seth Lakeman, Steve Harley and Sandi Thom. “Without doubt, VQ Live has outperformed any systems I have used before,” he says. “It’s probably the best point source box I have ever used in my career. Because it’s self-powered, the speed that you can set up is another big plus. It’s very user friendly, and although I did bring my laptop and the software to tweak around with the system, I
set it up for the very first gig. and haven’t touched it since.” Others view coaxial designs as useful anyway, even if compromised by other contexts. Suppose a coax could improve the HF in a line array element: there are still benefits to the overall picture. That’s exactly what JBL has done with the new D2 ‘Dual Driver’, a key element of the VTX line source system: it uses two voice coils, custom phased and feeding the same exit chamber. It’s not billed as a coaxial solution, any more than any mongrel could be a thoroughbred, but it claims significant improvement to clarity and SPL in the high frequencies. APG’s executive VP of R&D and marketing Grégory Dapsanse maintains that it’s all about the distribution of the cabinets within the venue, if your priority is to exploit co-ax to the full without compromise. “First of all let’s take the traditional coaxial loudspeaker: a loudspeaker cabinet equipped with two drivers aligned on the same axis, so that the HF driver radiates from the same point as the LF driver to create a single point source,” he says. “It is possible to design powerful distributed systems for large venues such as theatres or conference centres. In this case sound is distributed by a single loudspeaker at each point in order to limit interference. Properly designed distributed PA systems can be an excellent solution because they provide the same colour and tone
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