Issue 26
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Huge New Sport Complex for National Games of China

Billion-dollar build packs audio redundancy at every level, meeting Chinese standards of technical excellence all round


5 August 2021

Purpose-built to host the upcoming 2021 National Games of China, Xi’an Olympic Sports Center is the largest sports venue in the north-western province of Shaanxi.

Completed in July 2020 with a total build cost of $1.12 billion, the centre occupies an area of 866,667 square meters and houses three distinct venues: a 60,000-seater athletics stadium with track and field facilities; a gymnasium capable of seating 18,000 people; and a swimming and diving hall that accommodates 4000 spectators. After the 14th National Games draw to a close, the centre will transition to hosting international sports events, exhibitions and conferences in addition to acting as a multi-function sports centre for nearby cities and towns.

As the plans for the ambitious project were put into action, the contract to design and supply the audio system for the Xi’an Olympic Sports Center was awarded to distributor and installer EZPro, who were tasked with delivering a reliable “always-on” solution that was also flexible and easy to use.

“The challenges we had to overcome in the system design of Xi’an Olympic Sports Center included long-distance digital audio signal transmission, D/A signal switching and audio signal delay” explains EZPro’s Zhang Xianjun, the project’s technical designer. “When it came to specifying the six digital mixers for the project, we knew that with Dante cards enabling the scalable redundant audio transmission, Allen & Heath’s digital mixers would fit the bill nicely ”. All three of the Allen & Heath product families deployed in the install – dLive, Avantis and SQ – are built on the XCVI 96kHz FPGA engine, delivering a consistent standard of high-resolution low-latency audio across the main and backup systems, regardless of their form factor.

To ensure no disruption to audio in the event of a single point failure, EZPro implemented redundancy throughout the system, from microphone to loudspeaker – and everything in-between. At the input stage, non-redundant analogue sources are patched through passive splitters to deliver discrete signals to the main and backup systems. In each of the three venues, a pair of Allen & Heath mixers are deployed, running simultaneously at all times, allowing seamless switchover in the event of signal loss. Dante outputs from the main and backup mixers feed the Primary and Secondary Dante networks respectively, with a third independent network utilised solely for control signals throughout the complex. At the output stage, amplifiers with both Dante and analogue inputs were the preferred choice for peace of mind. The Primary Dante network feeds the amplifiers directly, while the secondary Dante network output is converted to analogue – via Allen & Heath’s DT168 Dante I/O expanders – to provide a redundant signal to the amplifiers.

For the main stadium, a dLive C3500 Surface is partnered with a CDM48 MixRack to form the main system. The dLive C3500 is the most compact dual-screen Surface in the dLive range, enabling the operator to take advantage of dLive’s Harmony UI, whilst maintaining a compact 24-fader frame size. As with all dLive systems, the MixRack offers 128 channels of input processing, with a configurable 64 bus architecture, allowing the installer to choose a MixRack I/O configuration to suit the application. For the stadium’s backup system, EZPro opted for an Avantis, a standalone mixer offering 24-faders in conjunction with 64 input channels and 42 mix busses, plus a GX4816 I/O Expander to mirror the analogue I/O of the primary system. Both the dLive and the Avantis are fitted with Dante I/O cards to integrate with the Primary and Secondary Dante networks. At the other end, a rack of 34 Powersoft Quattrocanali 4804 DSP+D amplifiers – connected directly to the primary Dante network, with the secondary network converted to analogue via DT168 – feed the 136 EAW speakers located throughout the stadium.

In the gymnasium, the main system is also built around a dLive C3500 Surface, this time paired with the compact CDM32 MixRack, with an SQ-7 employed as the backup system. The SQ-7’s 32 onboard mic preamps mirror the 32 mic inputs on the CDM32, with 33 faders on hand for control. As with the stadium, both systems integrate with the Dante networks via Dante I/O cards to provide redundant Dante feeds to the gymnasium’s Powersoft amp rack and EAW speakers.

The choice of Allen & Heath’s flagship dLive system in the stadium and gymnasium was in no small part down to the modular nature of the system, and the flexibility this offers when it comes to the location of the Surface. “In the main stadium and gymnasium, there is no openable observation window in the control room” notes EZPro’s Zhang Xianjun. “As the dLive audio engine is in the MixRack, we can confidently change the location of the Surface when required. We can effectively reduce the risk of control interface crashing, and at the same time meet the requirements of a flexible tuning position, ease-of-use and fast setup.”

In the swimming and diving hall, where visibility is not an issue, a pair of SQ-6 mixers are deployed as the main and backup mixer, with Dante cards fitted to both for redundancy of the networked audio, again feeding Powersoft amps and EAW speakers. For the natatoriums more modest requirements, the SQ-6’s 24 onboard mic preamps, feeding the 48-channel / 36-bus mix engine, was sufficient to meet current and future requirements.

With the facility now open for business, the design and install of the system was viewed as a resounding success by all involved. “The schedule was pressing, yet the sound system installation and commission were finished on time thanks to EZPro’s efforts,” says Zhou Jun, Chief Technical Engineer of the stadium project. “Third-party experts were invited to provide feedback, and they returned a high recommendation. The delivery was accepted without any doubt, and it meets the high Chinese standards for fabulous technical performance”.

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