India's Summer Games
Feb 1, 2002 12:00 PM, By Christopher Buttner
The Central Public Works Department of the Government of India built the Jawahar Lal Nehru Stadium in New Delhi in 1982. The massive facility is an all-purpose sports arena hosting soccer and other sporting events, as well as large-scale performances and concerts by India's leading entertainers. The facility seats 75,000 for soccer games and as many as 100,000 for other athletic events and for concerts. The Jawahar Lal Nehru Stadium also houses the headquarters for the Indian Olympic Committee. India hosted the first Asian Games in March 1951 in New Delhi and the eighth Asian Games in 1982 when the Jawahar Lal Nehru Stadium was first constructed.
Last year, the CPWD contracted New Delhi's leading sound design and installation firm, Electrorama, to design a new all-weather, high-fidelity, wide-dispersion sound system for the Afro-Asian Games, which were to be held in New Delhi in November 2001.
Regrettably, recent international tensions have led to the postponement of the Afro-Asian games, but other events still regularly take place in the Jawahar Lal Nehru Stadium. The sound system was only part of the massive upgrade to the stadium, which also involved installation of thousands of new seats, a complete track and field resurfacing and upgrade, and improvements to concessions, security, electrical and plumbing systems.
Not known for being particularly sparing on loudspeakers, New Delhi's summer climate is characterized by stifling humidity and temperatures of 90° to 100°F. Two months of rain in both the spring and fall, and winters with lows in the 40s, round out the environmental challenges to outdoor sound systems. The previous sound system had survived India's radical climate conditions for 19 years, but not without frequent repairs. Not only did the Government of India want pristine sound for the inaugural Afro-Asian Games — the most prestigious sports event ever to be hosted by the city of New Delhi — the CPWD also wanted twice the life span, increased output and fidelity, and a reduction in the frequency of repairs.
Electrorama Rises to the Task
Established in 1990, Electrorama has a staff of 25 full-time employees. The company specializes in all forms of sound, lighting and multimedia systems integration and installation projects for facilities such as theaters, stadiums, arenas, cinemas (projection and Dolby surround sound systems) and other government CPWD projects. New build and retrofit system integration projects comprise the bulk of Electrorama's business, according to Sunil Chauhan, one of the company's directors, with over 25 years of systems integration experience.
Electrorama's redesign work for the Jawahar Lal Nehru Stadium's new sound system began in early 2001, and plans were provided to the CPWD in late spring of the same year. Work began in July 2001, and the project was completed in late October. The sound system design criteria called for a dual-purpose sound system that could provide wide dispersion, high intelligibility, speech-only output for sporting events and high-fidelity, full-range delay for concert events.
Mounting and Fidelity Limit Speaker Options
The sound system had to be capable of delivering 97 dB SPL to the back of the front bleacher sections, 66 feet (20 m) from the speakers, and 90 dB SPL all the way to the last row of the top bleacher sections, 158 feet (48 m) from the speakers. Furthermore, the sound system had to be physically low-profile so as not to obstruct sight lines of lower-level seating, as the speakers are mounted on a series of 25 existing 28-foot (8.5-m) steel poles that are evenly distributed around the perimeter of the playing field. Every seat in the stadium is open to the environment as the structure has no overhanging roof. Thus, there are no additional places to support or suspend a fold-back delay sound system apart from the poles. Part of the criteria even stated that the near- and mid-field speakers could be no wider than the mounting poles themselves.
The larger long-throw, wide-dispersion speakers were to be mounted at the top of the mounting poles to fire 158 feet (48 m) to the back seating areas. The smaller near/mid-field audience speakers were to be mounted at approximately 13 feet (4 m) high and the playing field speakers at approximately 20 feet (6 m) high. The VIP seating areas would have two smaller near/mid-field speakers mounted to a 6.6 foot (2 m) pole, augmenting the larger speaker configurations flanking the VIP area.
All other long-throw speaker cabinets that were researched proved too large for the restrictive sightline obstruction criterion that was written into the spec. They also simply did not have the combined long-throw and wide-dispersion characteristics required to evenly cover all the seating areas from only 25 speaker-mounting poles. Moreover, these other speakers lacked the fidelity to be good candidates for a concert delay ring, as well as a speech-only system. Overall, they were too “beamy” and harsh-sounding in the close seats, and mid-rangy like AM radio in the further seats.
“Plus,” Chauhan points out, “long-throw (High-Q) stadium speakers have such a tight dispersion pattern that in order to effectively cover the large seating areas, we would have had to mount as many as six speakers per pole, per seating section, for as many as 12 speakers per pole. This would have resulted in large loudspeaker clusters that would have compromised the sightline criteria of the project and sent the system price soaring.”
Adding to the complexity, the design called for a 70-volt system since the cable runs from the equipment rack rooms to the speakers ranged from 656 feet (200 m) for the shortest cable run to as long as 984 feet (300 m).
The Inescapable Weather Factor
In addition to the mounting, coverage and sight-line challenges, the Jawahar Lal Nehru Stadium installation called for all of the speakers to be angled upward, thereby exposing driver components directly to the weather. Chauhan states, “There is no roof structure from which to mount speakers in a semi-protected area so they fire down onto the seating areas. Such a mounting technique can triple, if not quadruple, the life span of a loudspeaker system. In this installation, with the speakers firing up toward all of the seating areas, we had a real concern that the speakers would fill with water.”
The staff was convinced upward-mounted, bell-shaped speakers would fill with water during the first heavy rain. Combined with the beam-like output, obstructive size and unsightly appearance of such a speaker, Electrorama's design team eschewed such speakers and selected a loudspeaker that exceeded the strict design criteria for the project. Technomad Transformer loudspeakers were chosen as the front end of the system.
Having used Technomad Vernal 15T speakers as part of a distributed system upgrade in India's National Stadium, Chauhan and the Electrorama engineers were familiar with Technomad's output, clarity, low profile and durability. “We had competition in this project from many manufacturers,” says Chauhan. “But the Technomads, the smallest speakers we've found, featured the overall best output and durability specs [for this installation], including a U.S. Military Specification (Mil-Spec 810F). In this project, the Government of India is the client, and to them there is no better endorsement than a U.S. Military Specification for product durability. Once the client was aware of the Mil-Spec [and] our successful experience with the Technomad product, they were put at ease very quickly and were sold on the product.”
A System That Works
Driven by 25 Crown CH-1 power amps, the 25 Technomad Berlin 15T 300-watt, 70-volt loudspeakers provide ultra-wide dispersion and long-throw coverage for the upper balcony sections and VIP seating area. Ten Berlin 15T loudspeakers driven by Crown CH-1 amps completely cover the entire playing field area. The lower bleachers are covered by 35 Paris 616T 128-watt, 70-volt speakers, powered by 10 Philips LBD 8146 amps.
Chauhan points out, “The Technomad Berlin 15T is very efficient, [and] coverage is uniform both vertically and horizontally. Its 2-inch compression driver is mounted to a 120°×120° horn; so with a wide coverage output, we hit a complete seating section with only one speaker. The output of each Berlin 15T slightly overlaps the output of the speaker next to it to eliminate dead spots. The way they are mounted, the lower horizontal cutoff is right at the front edge of the upper section balcony and then just above the last row of the upper section. The Berlin 15T has a very wide, efficient and effective output that eliminates the need for extra loudspeakers.
“Physically, the Berlin 15T's driver configuration is correctly designed for its very shallow cabinet,” Chauhan continues. “The 2-inch compression driver and 15-inch bass transducer are aligned in the 11-inch-deep cabinet. So 48 meters out from the face of the speaker, the spectator is getting the low-end and high-end output just as accurately as the guy in the front row of the upper section, who is 25 meters closer to the cabinet. We have yet to find another speaker that can output such an even full-range sound. The low-frequency response is excellent, especially when you consider that this is a transformer-driven, 70-volt system. Technomad's high-end 70-volt approach works very well for us.”
The Paris 616T, also with a 120°×120° output from it's 1-inch compression driver, paired with its twin 6-inch bass transducers, also provides even and accurate vertical and horizontal coverage for the first-level and VIP seating areas. The output of the Paris 616T proved just as efficient as the Berlin, with dispersion cut off right above the last row of the first section to avoid reverberation in the overhanging upper section.
The balance of the signal chain consists of four Rane DA216 distribution amplifiers, one DOD 231 equalizer, and three Shure DFR11 time delays. The announcer's booth houses a Spirit by Soundcraft LX7 32-channel mixer, two Denon DCM 270 CD players, two Tascam 302 cassette decks, “And too many microphones, patchbays and ceiling speakers to even mention by brand and model number,” quips Chauhan.
Success In Spite of Snags
“It's a very clean-looking installation,” says Chauhan. “At 21 inches wide, the Berlin 15T is only about 12 inches wider than the pole to which it is mounted. The Berlin 15T and the Paris 616T were also custom ordered in a gray cabinet color to match the color of the mounting poles. So, for the most part, the vertically mounted Paris 616T, which is no wider than the mounting pole, is almost imperceptible, especially at night.”
Such a large-scale project does not come without installation problems. Electrorama's system design had originally called for 10 Crown-powered Berlin 15T loudspeakers to cover the playing field area, but governmental budget constraints reduced the number of playing field speakers to only six Paris 616T speakers.
Chauhan states, “When the job was cut back to only six Paris speakers for playing-field coverage, we knew the players would not be able to hear the game calls as well as the audience, if they heard anything at all. After the first game, we received a call from the CPDW requesting that the original 10 Berlin 15T field-coverage speakers and Crown amps be added back into the sound system, and that addition has recently been completed.”
Four engineers, two supervisors, eight technicians and one welder were involved in this project. While it appeared to be a simple enough install on paper, the reality of the project proved to be quite different. Pulling approximately 20 miles (32 kilometers) of cable took up a substantial portion of the 2-month installation time, and several days of heavy weather hampered workers from welding speaker brackets into place, thereby delaying the installation of the speakers. Sunil Chauhan jokes, “Yes, the Technomad speakers are weather-resistant, but workers on an 8.5-meter pole are not resistant to lightning.”
“For the tight requirements of the job spec, the Technomad speakers worked out perfectly,” he comments. “Once you start with a quality loudspeaker, designing the entire system backward from the speaker is much easier. A processed sound system, which was proposed by other companies, drove the costs up exponentially, thereby knocking them out of the running. By using such a good speaker, we've eliminated a lot of unnecessary processing from the signal chain and reduced the system cost and complexity while still delivering a much more expensive-sounding system.”
Christopher Buttner is a freelance journalist serving various entertainment technology manufacturing industries, including musical instruments, audio, video, broadcast, lighting, staging and multimedia systems integration. Contact him email@example.com.
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