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A South African DIAMOND

To accommodate growing passenger loads, South Africa's Johannesburg International Airport embarked on an ambitious project in 2000 to expand its domestic air terminal. DOMTEX, as the project was dubbed, was a huge undertaking.

A South African DIAMOND

Apr 1, 2003 12:00 PM,
By Craig Astler

Sub-Saharan Africa is no longer an outpost on the world air transportation grid. As the home to nearly 700 million people, the subcontinent is increasingly participating in international business and tourism, with Nigeria and South Africa — and to a lesser extent Angola and Gabon — seen as significant contributors to world trade.

South Africa’s Johannesburg International Airport (JIA), the primary airport in the region, has in recent years played a considerable role in Africa’s overall development. The facility employs 18,000 people, hosts 45 airlines from five continents, and services nearly 18 million passengers per year. JIA recently eclipsed the Cairo airport as the continent’s busiest air hub.

To accommodate growing passenger loads, JIA embarked on an ambitious project in 2000 to expand its domestic air terminal. DOMTEX, as the project was dubbed, was a huge undertaking. The terminal building itself is composed of five floors, three of which are each the size of three football fields. More than 80,000 square meters (860,000 square feet) in size, the structure will consolidate incoming and outgoing flights from three smaller buildings, allowing JIA to grow in capacity by nearly 40 percent.

Almost everything about DOMTEX is massive and state-of-the-art, including its audio system. Prosound, a South African sound and communication system supplier and the sound contractor for DOMTEX, knew from the start that the terminal’s audio solution would be critical to its overall performance.

“African airports historically have depended on their paging systems far more than facilities in other parts of the world,” says Terry Acres, founder and managing director of Prosound. “Public address and other audio information play a vital role in passenger control, especially as a single terminal will incorporate all airlines across the various boarding gates.”

Airports Company South Africa (ACSA) is JIA’s owner and controlling authority. When it specified its DOMTEX sound system needs, ACSA called for a world-standard solution that would be a long-term asset to the building. Unfortunately, while the system described in its initial bid was in many respects ultramodern, it also presented some sizable challenges, especially in its physical configuration.


JIA’s new domestic terminal is a bold piece of modern architecture, featuring dramatic volumes of space lined with aluminum, marble, and glass. Despite the open spaces and hard materials, the specs for the project’s sound system called for distributed clusters of compact, two-way, full-range loudspeaker boxes mounted on the structure’s supporting pillars.

“We were concerned that pillarmounted speakers would not properly address the acoustical challenges of the building,” says Mark Malherbe, Prosound’s general manager for systems engineering.

For paging, ACSA’s consulting engineers had specified a flexible control solution that would enable airport personnel to route pages to zones, or groups of zones, throughout the facility’s main terminal, parking pier, entrance atrium, and retail areas. A Peavey Electronics MediaMatrix digital signal processor (DSP) and PageMatrix controller unit — able to support message stacking — were chosen to be the processing backbone, based on their success in existing terminals at JIA. Officials knew the solution could also help solve the time alignment and ambient-noise-sensing issues in the terminal.

Other prerequisites for the system included background music, prerecorded announcement capabilities, and microphone routing to specified zones for special-events staging. Finally, the system was to be linked to the airport’s existing sound/paging system through fiber-optic cable.

Prosound had confidence in ACSA’s knowledge of airport needs; in fact, the sound system supplier had handled an upgrade of the airport’s main paging system five years earlier and had worked on other projects for the facility since then. However, Malherbe and his team believed it was important for Prosound to include an alternate proposal in its bid for DOMTEX — one that would address some of the acoustical inefficiencies of the specifications.

“Our EASE analysis showed that a ceiling speaker solution would be a better method for minimizing sound pressure level variance and time-related interference,” Malherbe says. “The pillar loudspeaker positions would have compounded the intelligibility problems, since an area can be covered by more than one loudspeaker from more than one point source. The additional time paths create multiple reflections and consequently reduce intelligibility. On the other hand, the ceiling distributed system ensures that all sound emanates from one plane [time base], and effectively, a listener only hears one speaker at a time — and is always close to a speaker — and thus experiences improved intelligibility. By replacing the pillarmounted loudspeakers with ceiling drivers, we felt we could provide greater flexibility and better audio coverage, all at a competitive price.”

Although the MediaMatrix DSP made sense, Prosound also believed certain operational aspects of the paging component could be improved with a different solution. The company turned to Creative Audio of Brisbane, Australia, to provide an integrated hardware and software paging alternative. Prosound selected Creative Audio’s S534 CobraNet-PCI card paired with MessageNet, the vendor’s proprietary paging controller. (Ironically, since the time of Prosound’s decision, Peavey Electronics has licensed Creative Audio’s paging control products and is now the international distributor for the system. It is marketed by Peavey as the ControlMatrix system.) Creative Audio had successfully installed the MessageNet solution as part of the paging system at the Sydney International Airport, and its benefits in mass transit environments convinced Prosound it would be a solution for DOMTEX. “Our feeling was that a MediaMatrix mainframe with a MessageNet-based paging system, using CobraNet as the common interface, would lower cost while providing all the required redundancy and message-scheduling functionality,” says Malherbe.

In August 2001, Prosound submitted its main bid and its counterproposal, along with EASE drawings and other supporting data, to ACSA’s consulting engineer for consideration. Although the project was heavily contested by other firms, Prosound was given the go-ahead to implement its alternative plan in October 2001.


DOMTEX is composed of two new structures and one revamped one. The new main domestic terminal is 200 meters long and 20 meters wide and holds five contact stands (places where passengers can walk straight from the building onto waiting aircraft), as well as baggage claim, ticketing, and a retail level containing shops, coffee bars, and a food court.

Joining and defining these spaces is a new three-level atrium — access point for a series of inclined travelators that link the departure, retail, and arrival levels. A pedestrian bridge connects the domestic terminal to the final part of the project, the airport’s five-year-old, 4,000-space parking pier. This pier, which also services the airport’s other terminals, was to be upgraded with an extension of the domestic terminal’s dedicated paging system.

For audio coverage in the terminal and parkade, Prosound chose the Altec Lansing CF204-8T ceiling speaker, which is a 4-inch (100 mm) loudspeaker/transformer combination. The moisture- and corrosion-resistant unit provides 10W EIA/40W peak power handling, low (<0.6 dB) insertion loss, and a frequency response of 150 to 18,000 Hz to accommodate a wide range of voice and music requirements.

“Altec Lansing 5385B speakers had been used in the past in the airport’s existing international and domestic terminals,” says Acres. “ACSA and the consulting engineers were comfortable with the performance of those products; however, as luck would have it, the unit had been discontinued by the Altec Lansing OEM licensee. Fortunately, our project coincided with the ‘rebirth’ of Altec Lansing Pro Audio as a division of Altec Lansing Technologies in 2002. The new division was able to offer the CF204-8T, which was a more than satisfactory replacement.”

A total of 1,062 CF204-8Ts were purchased for the main terminal and an additional 205 for the parking pier. To extend the drivers’ low-frequency response in the parkade, Prosound designed and built custom cube enclosures to load the CF204-8Ts. Painted to match surrounding aesthetics, the 180-by-180-by-180 mm timber veneer enclosures were mounted on swivel brackets and installed throughout the structure.

For the triple-volume terminal atrium, where the 12-meter ceiling height dictated a different kind of speaker, Prosound selected six Electro-Voice S×80 two-way loudspeakers at the atrium entrance. “The increased ceiling height meant the ceiling-style speakers weren’t feasible,” Malherbe says. “To achieve even coverage of the floor area, we chose units that had good constant directivity characteristics in the desired frequency range in order to control the dispersion on the floor area and away from any unwanted reflective surfaces. Because of the extra distance, we needed a higher-power handling speaker to achieve the required SPL. With the S×80s handling 175W, we had plenty of capability in this area.” Rounding out the collection of output devices were 52 Electro-Voice PA12 compact clear horns for the back-of-house luggage management areas.

Paging for the domestic terminal is accomplished through a total of 28 paging stations. All but two — one at the help desk and one in the terminal operations center — are for airline use. The other stations are distributed throughout the check-in counter, boarding gate, and baggage claim areas. While most stations are linked only to their nearest zone or group of zones, the help desk and ops center paging stations are supplied with additional flexibility to reach user-defined combinations of zones according to various paging needs.

In retail areas of the departure hall, some shops chose to deploy their own local sound systems. In those instances, a relay was provided for each shop that could be controlled by the MediaMatrix DSP. When urgent pages are required in the store’s zone, the local systems automatically mute. No background music or prerecorded announcements reach retail interiors, for which an alternative solution has been installed.


The DOMTEX audio system installation process began in April 2002 and followed a three-step schedule. First was the installation of fixed cable and infrastructure, a four-month process that proceeded as construction areas became available. Then all amplifiers and loudspeakers were installed, followed by processor installation and system testing as the last step.

Andre Buys, general manager for installations services and in-house project manager for the contractor, noted the extensive amount of wiring employed for DOMTEX. “We installed 15,000 meters of four-core 1.5 mm cabtyre cable, 3,000 meters of four-core 2.5 mm PVC Nitral (fire-retardant), and 3,500 meters of Cat-5eFTP,” Buys says. “Over 9,000 meters of single-pair cable and 850 meters of four-core fiber-optic cable were also used.”

All loudspeaker zones were wired with redundant amplifier channels; each zone was supplied with two amplified channels, running from a first or second amplifier. Although dual-channel amplifiers were used, no zone is fed from a single unit. Cabling for the speaker grid was achieved using the four-core, 1.5 mm cabtyre. In addition, a local distribution panel was installed at each zone in the grid, which was wired back to the amplifiers using the PVC Nitral cable.

At each paging station, one-pair microphone cable was installed along with Cat-5eFTP cabling for data and power requirements. All stations were connected to Peavey MediaMatrix CAB (CobraNet Audio Bridge) 8i or CAB 16i devices; the CAB devices were then wired back to Cisco network hubs using Cat-5eFTP. Because of the long runs to the main amplifier room (560 meters) and parking pier (280 meters), all hubs were linked through fiber-optic cable.

Two amplifier rooms were used, one each for the pier and the terminal. The terminal amp room was located on the roof of the building next to the CCTV, computer data, and paging control centers; into this space went 25 QSC Audio CX302V 70V power amplifiers, a reliable unit providing 250W of output per channel. Four more CX302Vs were installed in the pier development in a dedicated room on the second floor.

Once the wiring and amplifiers were in place, Prosound began the job of installing the nearly 1,300 Altec Lansing ceiling units. “We were very impressed with the quality of the packaging and the presentation of the CF204-8Ts,” says Acres. “When we saw drivers’ build quality, we were confident we would achieve a superior result from the system.”

According to Keith Pugin, Prosound’s on-site installation manager, the biggest challenge to the project was the coordination and physical installation of the atrium loudspeakers. “Almost 150 speakers had to be mounted in an area with a ceiling height of 12 meters,” Pugin says. “We had to work closely with the ceiling contractors who were fitting the 180-by-90 cm ceiling panels, as each speaker and its grille had to be mounted into the appropriate panel before it was set into place. We also had to keep moving, as the tile contractors were tiling the floor right behind us.”

Rounding out the installation process was the deployment of the control system. The rooftop main paging center became the home for a new MediaMatrix Miniframe 208nt DSP as well as two PCs — one for the MessageNet scheduler and a second PC for the control network.

Forty-eight inputs, one for each of the terminal’s 48 zones, were used in the MediaMatrix. All EQ, compression, delays, time alignment, and ambient sensing are handled by the Miniframe 208nt, along with the ability to link the entire system to the airport authority’s LAN for remote control purposes. Prosound’s system engineering staff can also log on remotely via modem for troubleshooting or system tweaking.

As a logic-based controller, MessageNet handles a variety of system events, from prescheduled announcements to priority stacking. The software’s user interface is designed for easy scheduling — something Charles Markotter, Prosound’s senior design technician, says was critical to ACSA. “With the number of paging stations and the stringent emergency evacuation requirements of DOMTEX, we needed a very smart message controller,” he says. “MessageNet has the flexibility to satisfy those needs yet is very intuitive to operate.”

Another operational advantage of the MediaMatrix/MessageNet solution is the built-in redundancy of the system. According to Markotter, even if both the Miniframe and the paging controller were to fail, the system would continue to function, although with less flexibility. “This satisfied the airport’s requirement for suitable system backup, because the main airport sound system can also take over the functions of the DOMTEX unit,” Markotter says.

Rounding out the DOMTEX sound system are Electro-Voice US600EL microphones for the paging stations and Electro-Voice Co5 Cobalt Series mics for ambient noise sensing. Peavey PCU-1 four-button paging stations are used in the public/passenger areas, with ten-button PCU-2 stations installed at the help desk and operations center.


Even though the DOMTEX sound system’s commissioning occurred just prior to the terminal project’s opening day on February 11, 2003, reactions from JIA officials and airline staff are already favorable. “The feedback during training was excellent,” Acres says. “Everyone involved was impressed with the operational simplicity of the system.”

Singled out for praise by the Prosound designers have been Altec Lansing’s ceiling units. “No amount of front-end control and manipulation has validity without a quality sound output,” Malherbe says. “That’s what we have with the CF204-8T drivers.”

Although video has not been an integral part of Prosound’s work on DOMTEX, phase two of the system will involve integrating the audio network with the terminal’s flight information display system. Before that gets underway, however, Prosound already has its hands full — it was just given the job of creating a comprehensive message-stacking solution for all of JIA.

“This airport has grown considerably over the last seven or eight years, and the construction hasn’t stopped,” Acres says. “We’ve hardly left the site during all that time.” With audio playing a major role in JIA’s operational life, it seems Africa’s busiest airport will be a showcase for Prosound, and for public sound systems in general, for some time to come.

Craig Astler is a freelance writer specializing in audio systems and other technology-related topics. A former advertising agency creative director, Astler lives in Cleveland. He can be reached at

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