Duran Audio Company Profile
The pioneering spirit of Duran Audio founder Gerrit Duran has driven the company’s technical quest as well as giving it an unmistakable character...
From Vincent van Gogh and the Flying Dutchman to Golden Earring and Johann Cryuff, the Netherlands is often perceived as the home of stylish pioneers that reaches back centuries. In this vein, the audio manufacturer founded by Gerrit Duran has developed a knack of blending art with science. Duran Audio prides itself in taking pioneering research out of the laboratory and using it to solve real-world problems.
Long before the planned world domination of Microsoft, Gerrit Duran was putting his PC to use to solve the electro-acoustic problems presented by loudspeaker designs. It was a bold leap of faith for the time, and Mr Duran openly admits sales of his technology were sluggish until the new millennium began. But having weathered several years of commercial famine, the Intellivox system has become the acoustic consultant’s weapon of choice in today’s tricky interior environments – especially those dressed in marble, glass and stone.
While studying Sculpture at Hertzgenbosch University, Gerrit Duran was a keen guitarist. His passion for music also extended to other instruments and he still gets his kicks in trying to get the best amplified sound quality for marimbas and xylophones. It was while he was on stage that Mr Duran’s fascination for PA systems developed: ‘I was concerned with the poor sound quality and became a hobbyist producing my own speakers,’ he recalls. His enthusiasm soon overtook his studies, and in 1981 he founded Duran Audio to develop Source System – one of the first actively controlled and self-powered loudspeaker systems on the market in 1986.
Four years later the company was restructured, making Duran Audio the R&D section and manufacturing part of the company while Axys was created as the brand name. The Modular Array Controller – better known as Mac28 – was launched in 1993. ‘The objective with Mac28 stemmed from my playing years, when I wanted to project the sound image from the stage to the audience. The steering concept came from this.’
Referred to as Digital Directivity Control (DDC), this multichannel loudspeaker array technology allows each loudspeaker channel to have its own dedicated audio path through the DSP and amplification using 28 channels of DSP-controlled amplification. Each loudspeaker is given its own unique set of filters, allowing electronic manipulation of an array’s vertical dispersion pattern. The controlled directionality of the beam made it an obvious choice for use in venues with a flat listening plane and the authorities at Amsterdam’s Schiphol Airport were quick to pick up on this In the following year, with the airport becoming the first commercial installation to incorporate DDC technology – a Mac28 controller combined with a custom designed speaker array. ‘At the time, the term DSP hardly existed and all the programming had to be performed in machine code,’ Mr Duran recalls.
The concept of steered beams and the Wave Field Synthesis (WFS) at its core captured Mr Duran’s imagination: ‘When we first delved into this branch of acoustic development, we didn’t consider Wave Field Synthesis,’ admits Mr Duran. ‘However, with Mac28 this is exactly what we were working on. It was a theory and we were taking it into practice, so we teamed up with Diemer de Vries at the Faculty of Physics at the University of Delft to dig deeper.’
WFS is a spatial audio rendering technique, characterised by the creation of virtual acoustic environments. It produces ‘artificial’ wave fronts synthesised by a large number of individually driven speakers. Such wave fronts seem to originate from a virtual starting point, or virtual source, where the localisation of virtual sources in WFS does not depend on or change with the listener’s position. In time, Duran Audio investigated the relationship between beam steering and WFS, with PHD student at Delft Evert Start assisting and later joining the company: ‘By manipulating interference by adjusting filters and such like, you have redefined the signal path. This is positive interference.’
Initially designed for use in theatres, Mac28 and DDC prompted Mr Duran and his R&D team to focus their attention on the concept of beam steering, resulting in the unveiling of Intellivox 2C in 1996. It was world’s first commercially available, fully-integrated, digitally-controlled loudspeaker array, with network control executed from a host PC running DOS. ‘When we first introduced our beam steering technology to the world, we had no idea what we were starting,’ continues Mr Duran. ‘People questioned our sanity when we announced that we could electronically steer a beam of sound using a fixed array of loudspeakers and it took some time for the majority of system integrators and consultants to believe in it. It was around this time that we started to work closely with architects and consultants. I knew that we could offer them the technology for their needs, but from the outset many didn’t understand it. We were always pragmatic in saying “this is what can be done” rather than “here’s the solution”, as the technical solution is always compromised by real -world situations.’
In visual terms, Intellivox has been compared to a spotlight as opposed to a floodlight, producing very narrow vertical coverage with very wide horizontal coverage. In large reverberant spaces, Intellivox causes significantly less sound to be reflected off walls and ceilings, and is highly efficient at distributing the available power from the loudspeaker. As such, the SPL of the loudspeaker is approximately the same whether the listener is in close proximity or 60m away, resulting in a very natural, clear and direct sound. This is an essential characteristic for those consultants who demand speech intelligibility as one of their main criteria during public announcements. However, the technology they had devised was so far ahead of the market at the time, that they were fighting a lone crusade. ‘In recent years, other loudspeaker manufacturers have entered the market with beam steering designs and this has actually helped our cause,’ confesses Mr Duran. ‘It’s a clear sign that the philosophy is now accepted, but it was hard for many years as many listeners wouldn’t accept what they were hearing.’
Intellivox also fitted the bill from an architectural perspective, allowing a speaker to easily blend into a building and sound to be heard without the loudspeakers being seen – in accordance with the majority of architects’ wishes. Impressed by its aesthetic and acoustic characteristics, increasing numbers of consultants were becoming aware of Intellivox. ‘It was hard for us to catch the attention of consultants working on big projects and it therefore took us some time to gain their confidence,’ furthers Mr Duran. ‘However, as the 1990s progressed, we managed to work on some pretty high-profile projects, which has helped us get into the position where we are now.’ A series of railway and airport projects took time, but eventually came to fruition. ‘These projects have a very long incubation time. For example, the Lehrter Bahnhof in Berlin started its development in 1994, but we didn’t install the system until 2006. That’s a long time to wait before your order comes in.’
Following in the footsteps of Digital Directivity Control, Digital Directivity Synthesis (DDS) technology was introduced in 2000 as a solution for those applications with more complex seating areas, such as a raked seating area or split level. DDS provides the power to synthesise any desired 3D radiation pattern from a loudspeaker array to meet the specific needs of the venue. Rather like ‘an eyeglass in reverse’, the direct SPL distribution in a more complicated room shape is determined by calculating the optimum output filter for each array channel, so that the desired ‘acoustic illumination’ is mapped back to the array, instead of mapping the array response to the hall. DDS facilitates the best possible coverage with the maximum direct-to-reverberant sound ratio for any given situation. DDS not only defines the area to be covered but also defines those that should be avoided, resulting in the best possible suppression of unwanted reflections, which is invaluable when controlling stage-feedback or suppressing rear wall reflections. With the integration of the dedicated Digital Directivity Analysis (DDA) software, the array position and the audience area can be defined allowing the DDS algorithm to produce a best possible fit, resulting in a complex dispersion pattern. DDS technology was successfully integrated into all the Axys Intellivox and Target products four years after it was introduced in 2000.
The Intellivox family has gained the respect of consultants requiring precise announcement and messaging systems, but in comparison to music systems the frequency range required for BGM was limited. With the recent addition of the DSX range, which includes 1-inch horn-loaded dome tweeters in their design, the frequency range has been extended to cover 130Hz to 18kHz, specifically for those applications that require improved music clarity in addition to speech intelligibility. The small Intellivox DC and DS column footprint measures just 134mm in width by 92mm in depth and is available in various lengths (1,150mm, 1,800mm, 2,800mm, 4,300mm and 5m), with the longer arrays providing more control over directivity. Each array is composed of 4-inch drivers together with built in amplification and DSP.
The DSX products share the same dimensions and lengths (there is no 1150mm model), but include a small horn array. Slightly larger, measuring 198mm wide and 156mm deep, to house 6.5-inch drivers, the 1,278mm DC/DS 808 and the 3,738mm DC/DS 1608 offer even wider frequency ranges. Voice announcements in public areas such as airports and civic buildings are paramount, so the Intellivox speakers are equipped with an RISC (reduced instruction set computing) processor to manage surveillance routines, such as pilot tone detection, amplifier load and ambient microphone surveillance. Twenty of these are performed each second, and the RISC is furthermore monitored by a watchdog, so that in the event of a failure, it will reset the RISC. All relevant status parameters and temperatures can be monitored via the RS485 network.
Intellivox continues to evolve, and the ADC range was unveiled in 2005 for use in 70V/100V public address and voice alarm (PA/VA) systems. Each array consists of six carefully aligned 4-inch speakers housed inside a tough steel enclosure. The V90, on the other hand, uses a preset vertical opening angle to cover the listening plane when mounted flat to a vertical surface resulting in a reduction of incoherent reflections from the mounting surface. The H90 has been designed to evenly cover distances up to 15m, minimising the spill over a large bandwidth outside the listening area such as on open railway platforms and in high ceiling corridors. Originally developed for Berlin’s main railway station, the DS-90 IntelliDisc became the world’s first fully-integrated, digitally-controlled, two-dimensional loudspeaker array when it was launched in 2006. The unique speaker solution offers control over both the horizontal and vertical beam steering, where the dispersion can be shaped to a very narrow beam.
Without doubt Intellivox is the flagship product of the Axys range, but Duran Audio is no one-trick pony. DDS technology was successfully transferred to form the basis of the Arena System and from this, the Target PA system followed. Again, these systems mould the array dispersion electronically to the audience space. ‘Re-entering the touring and theatre market has become a priority for us,’ confirms Mr Duran. With the development of Target system, Axys boasts a scalable, self-powered loudspeaker with built-in DSP that provides a level of control previously unavailable in a touring system. ‘Like Intellivox before it, Target seems to be misunderstood. Many listeners think of it as just another mechanical line array. But Target is electronically steered and is totally different. Luckily, some other manufacturers are also producing their own versions now and hopefully this will help bring attention to Target.’
When the Dutch manufacturing powerhouse Philips knocked on his door 10 years ago with a problem required an audio solution, not even Mr Duran could have envisaged the outcome: ‘The Dutch are ahead of most countries when it comes to legislation and new laws were being passed around 10 years ago regarding safety in road tunnels,’ he says. ‘At the time, we were considered the speech intelligibility experts and Philips wanted us to assist them in producing a voice evacuation system that they could universally install with the CCTV and sprinkler systems.’
Duran Audio was confronted with a real and interesting problem, but a solution was going to take several years. Extensive research followed. ‘Once again, we took on the role of pioneer as no-one had researched sound in tunnels before. We found that the acoustic properties of tunnels varied considerably depending on the size of the tunnel, the type of asphalt surface and whether the tunnel lining and roofing was brick, tiles, rock or concrete. Fire restrictions such as cladding also greatly changed the acoustics as well. We came up with a line array solution, but that was deemed to be too expensive. We visited some tunnel control rooms – I was astounded that these places existed and the technology and sophistication of them.’
Road tunnels have become big business following the development of the Axys ABF (Asymmetric Boundary Flare) 260 long-throw, directive horn. The design fits the bill, working within a frequency range up to 8kHz, with one unit is required for every 50m stretch of road. The ABF geometry is essentially half of a horn and was designed on the principle of acoustical mirroring, which creates the ‘other half’ of the horn. The ABF is mounted on the ceiling, which acts as a waveguide, reducing lateral reflections and obtaining a coherent wavefront. Four speakers are cabled to a four-channel amplifier in the control room, where the DSP properties can also be configured, to maximise the SDI (surface diffusivity index) depending on the variables of that particular tunnel, which is also changed by the volume of traffic and ventilations systems. ‘Finally, we had to integrate and synchronise the voice evacuation system with the CCTV, video and sprinkler systems, so that in the event of an emergency, everything would interact.’ Installations to date include the Benelux tunnel in Rotterdam and the Blackwall Tunnel under the River Thames in London.
‘By nature, our products weren’t designed for box shifters. It’s complicated and we need skilled people to go with it. As with all technology today, in the wrong hands it can be awful. L-Acoustics was one of the first companies to see this in audio when the V-Dosc was introduced, and I can see specialists becoming more prevalent as more technology is used in our industry – just to ensure people get the most from the product.’ It’s going to be a challenge however as their list of prestigious applications is vast. If you’ve sauntered through an airport such as Singapore, Dubai or New York’s JFK, the chances are you were guided to your gate or check in area via Intellivox. London’s Paddington station, the Louvre gallery in Paris, Florence Cathedral, the Cathedral of Immaculate Conception in Hong Kong, the Grand Mosque in Abu Dhabi, Braga Football Stadium in Portugal, Dubai Airport and Croke Park Stadium in Dublin represent just a handful of their achievements.
Such has been the upward curve in growth over the past decade that larger manufacturing, research and development facilities were required, and opened in 2007. Located in Zaltbommel, these are a shining example of how a production facility can maximise both energy efficiency and performance. The architectural challenge for Duran Audio’s new facility included creating a building, which also reflected the personality and qualities of the company founder. The architectural design is both refreshing and environmentally aware and it’s an extension of the owner’s design philosophy, whose researched his subject matter tirelessly in coming up with the final designs. The facades of the building, where the offices are located, are covered in handmade ceramics, and contrast sharply with the rigid metal elements of the production facility at the rear of the building. An integral part of the design is the single curved wall, which runs the entire length of the building and acts as a divide between the office area and the production area.
The main energy saving feature of the building is the ground source heat pump, which has a well 60m deep and delivers heat to the building through a combination of under-floor heating, climate ceilings and the ventilation system. The ventilation system provides a constant flow of fresh air through the building, which as a result has no opening windows. Heat is added and removed from the system using a heat exchanger. ‘The result is a constant comfortable temperature all year round and we save a lot of money in heating as a result.’
The Netherlands is possibly the most environmental aware nation on the planet, but Mr Duran was challenged by the lack of assistance shown to him in executing his plans: ‘The contractors really weren’t that bothered and the government offers no initiatives to businesses to go green like this.’ Once again, his pioneer spirit was ahead of those around him – it’s quite likely that in 10 years time, these original construction ideas will be the norm. The production and assembly areas don’t mirror those of a box shifter and adapts itself to the solution they are working on at any given time.
Duran Audio’s business in the Middle East and Asia-Pacific regions started in earnest with Dubai Airport’s insistence to install Intellivox speakers in 1999. Since then, the manufacturer has been shipping increasing amounts of speakers into mosques such as the Abu Dhabi Grand Mosque, airports, colleges, venues and function rooms. Duran Audio and the Axys brand may be almost three decades old, but one feels that the best is yet to come from this Dutch master.
Published in PAA November-December 2009