> Putting sound at the Centre
UAE: Ateïs ME is becoming known for creating solutions for seemingly impossible acoustic spaces. Mirdif City Centre mall presented another challenge as Richard Lawn discovers
Shopping malls have come a long way in Dubai since DeiraCity Centre first opened its doors in 1996. In terms of size and opulence, the bar has been continually raised – first at Burjuman and then Ibn Battuta, Mall of the Emirates, Festival City and Dubai Mall. One could be forgiven following the recent economic downturn that the last thing the retailers in this Emirate need is another high class shopping mall. Nevertheless, having begun construction of Mirdif City Centre in April 2007, the Majid Al Futtaim (MAF) Group pressed ahead regardless.
In terms of voice evacuation and public address, Dubai’s malls have engaged different consultants and, as a result, varying systems have been installed by different integrators. Each mall varies from containing discretely installed variations of in-wall, ceiling and column speaker solutions. Mirdif City Centre, however, insisted on using the manufacturing specialist Ateïs, a company that firmly put itself on the Middle Eastern map in 2007 with its unique handling of Dubai Festival City.
The suburb of Mirdif is a commuter belt of Dubai that until 16 March – the day Mirdif City Centre opened – was characterised as being on the eastern approach flight path to Dubai International Airport. Located at the corner of Emirates Road and Tripoli Street, the new mall has seemingly altered that perception for good. Occupying 550,000 sq-m of space on two floors, it is similar in size to the Mall of the Emirates, boasting some 440 retail outlets, 7,000 car parking spaces, two food courts, cafes, restaurants, a Carrefour hypermarket, a 10 screen cinema complex, an outside cinema, Magic Planet children’s entertainment area, and an “iFly” indoor skydiving centre.
Al Jaber LEGT was designated as the construction contractor of the AED 2.0-2.6 billion project, while (ALEC) LLC was sub-contracted to handle the electrical engineering. In their roles as architects, both RTKL and Holford Associates worked closely with interior designer KCA International to ensure that the aesthetic properties of the mall were precisely executed by all the sub contractors. Audio was a key requirement, but in an expansive shell of glass and marble, the interior designer wasn’t keen on having its sleek designs distracted by loudspeaker placements.
Discretion was the key. Like Festival Centre, Mirdif City Centre decided to distinguish itself from the other malls by commissioning Ateïs to install a series of innovative audio requirements into its ornate fabric. Rather than adhering to the background music requirements with a combination of concealed ceiling and wall speakers, Ateïs once again introduced its digital beam-steering line array technology into the shopping environment.
Digital beam steering is becoming more commonplace in professional audio, but the concept of fully software-controlled arrays being used in a fixed installation environment such as a shopping mall is still unusual.
Ateïs succeeded with good effect with their radical designs in Dubai Festival City, but applied new technology and ideas three years on at Mirdif City Centre. The two levels of the mall are expansive, having been divided into North and South, East and West and Central Galleria walks. Upon entering the impressive Central Galleria, with a ceiling height of approximately 20m, it is easy to understand why there are no ceiling speakers here.
Music is definitely in evidence however, although the sources are not immediately apparent. It would appear at first evidence that Ateïs has overcome what is a highly reverberant acoustic space with a system comprised almost entirely of fixed DSP-controlled arrays which combine to offer intelligibility with an even distribution. For shoppers and architects alike, it ticks all the right boxes. ‘The client requested an intelligible sound system not only for announcements and voice evacuation, but also high-end sound for events,’ explains Hussam Al Haddad, Ateïs Middle East general manager.
The Central Galleria often hosts fashion shows and car launches enabled by three outside broadcast points, whose audio, video and lighting feeds lead to a mixing position located above on the first floor. Three Messenger G2 models have been integrated into the overall design of Mirdif City Centre Mall providing broadcast quality signal to noise ratios, a musical frequency response, pro-sound power handling and advanced processing abilities. ‘A distributed sound system was out of the question, so we proposed the Messenger speakers for the mid-high range, although we also needed to deliver the low frequency response required for live performances in this area, and this provided by the Messenger 2XL column speakers. The complete system was designed to comply to BS 5839 part 8 as well BS 6259 and the Dubai Civil Defence Authority demands. Once the system ceases to be used for a live event, it switches over to automatic evacuation, which in turn is linked to the fire alarm system of the mall, via a single key switch turn, the system changes over to manual evacuation allowing the well trained operator to react to the evacuation messages and commands when needed.’
A main system comprising single 6m Messenger 2XL arrays are channelled up and down the lengths of the malls, while a larger number of Messenger L arrays augments and completes the mid-high system. Like Festival City, Ateïs Middle East has deployed its Messenger series of fully digital side-lobe free arrays to deliver both BGM and voice evacuation announcements. Two Messenger 2XL arrays have been installed into the walls of two lift shafts that connects the two levels between east and west walks with Central Galleria, two of which face up the mall and two downwards. Measuring 6m in height, the 2XL array employs 48 channels of 70W class-D digital amplifiers operating within a frequency response of 50Hz to 1.5kHz, and is capable of producing a maximum SPL of 93dB at 80m.
‘When we first came on site, there was a delay of 5.2s. Now there is a 151ms delay over a distance of 90m,’ Mr Al Haddad adds, proudly. ‘We have overcome the acoustic properties of the mall by carefully synchronising the various galleria corridors from a point called time zero. The 2XL speakers were timed to the entrance and from these readings the other Messenger M and L speakers have been delayed and synchronised accordingly. Every one of the 280 circuits on the plan was synchronised at every point over a period of three days.’
While the 2XL arrays cover the lengths of the Central Galleria, known as Palm Court, a number of smaller Messenger L arrays have also been installed to cover the widths across the Central Galleria. Standing 2.39m in height and incorporating 18 70W amplifiers, the Messenger L columns can also produce a maximum SPL of some 94dB at 30m distance. Covering the slightly narrower east and west walks, spaced at 25m intervals, Messenger M speakers have been installed onto the upper balconies facing downwards to cover the lower mall reaches. Measuring 1.345m in height, each Messenger M speaker consists of 12 70W amplifiers providing a maximum SPL of 94dB at 25m, over which distance they lose just +/- 3dB.
The Ateïs Middle East designers clearly did their homework in advance and mapped out the time alignments perfectly, channelling the audio directions of the Messenger speakers along corridors. The Messenger M model was specifically designed for this project in such that the height had to be restricted to 1.35m, so they matched the height of the upper walkway. Furthermore, the colours of the housings have been matched to the interior design paintwork. In order to make the Messenger M speakers fit in this manner, they have had their external power suppliers removed and so the 100V line driven speakers receive their power supplies from 18 racks located in 10 electrical rooms throughout the mall.
The lower ceiling corridors leading from entrance to the taxi drop off areas and car parks, required a ceiling speaker solution, as did the toilets which have been installed with CS4 speakers for example. Once again, these speakers had to be time aligned, as did 400 back of house wall mounted Sentry 6 speakers that have been installed on one wall only and delayed by some 135ms to match the speakers in the mall corridors, should a door open.
Furthermore, a large quantity of Ateïs RCS6FTS fire domed ceiling speakers, SM500 Soundtube wall-mounted speakers, 110 RS600 wall-mounted Soundtube speakers were installed and time aligned accordingly throughout the mall, together with 400 PH10-TC horn speakers in the adjoining car parking area.
Mirdif City Centre Mall’s public address, voice evacuation and pro-audio system is operated over the Ateïs secure digital network Linked Audio Processor software, providing 48 audio channels over a 13km distance with fire-rated Cat5 fibre-optic cable. The system connects 17 nodes of LAP units and integrates with the IDA, which is the heart of Ateïs voice evacuation to cover the 280 speaker circuit zones. In the event of a power blackout, the Messenger speakers also come with two rack-mounted battery back-up power supplies, allowing the Mall’s announcer to broadcast evacuation messages during a time of necessity.
Having added a second prestigious flag to its noted Dubai Festival Square system, Ateïs Middle East has once again carefully adhered to its client’s brief and conjured up a highly intelligible PA/VA system. A projected 17 million shoppers will pour through the doors of this high class mall over the first 12 months, and so the omens that too many malls are enticing too few shoppers to Dubai’s retailers seem remote. Having experienced the other malls in Dubai before the creation of Mirdif City Centre, Dubai residents have high expectations of intelligible and even sound. However, from the expressions of those tourists visiting the Mall, it would appear that retail therapy such as that experienced in Mirdif City Centre never sounded so good. Ateïs has once again raised the level of excellence, while steering and spacing their beams in a discrete manner.