The largest and most versatile sports venue in China’s Shaanxi Province, the US$1.12bn Xi’an Olympic Centre Stadium seats 60,000 in its main stadium; 18,000 in its gymnasium and 4,000 in its natatorium. The venue is set to host the opening ceremony and track and field competitions for China’s National Games in September.

Responsibility for designing a high-quality ‘always-on’ audio system spanning the US$14m stadium’s three zones fell to distributor EZPro International. advanced, stable, cost effective and flexible,’ says EZPro Technical Manager, Yongjun Jiang. ‘The brief we were given was to create a world-class audio system.’

‘That was with the system working as an entertainment, voice and emergency system,’ he continues. ‘It was vital we used the best in the business to create the most reliable and impactful system possible. For us, this meant using top brands with the best technology on the market, including Powersoft.’

After investigating each venue’s size and acoustics, and recognising speech intelligibility as the most vital aspect of the audio set-up, EZPro decided that the three venues of the sports centre were to be given different system layouts. In all, EZPro installed 236 EAW loudspeakers, nine Allen & Heath digital mixers, four Symetrix processors, and 43 Powersoft Quattrocanali 4804 DSP+D amplifiers controlled by ArmoníaPlus software.

‘Speech comprehension was the most significant aspect of the audio requirements, with the upcoming games and competitions held in the venue relying heavily on commentary,’ Yongjun explains. ‘The stadium and natatorium adopt a distributed layout to ensure coverage to all the seats, while we opted for a more centralised lay out for the gymnasium, as it’s a smaller venue. Each EAW loudspeaker is given its own independent channel, allowing to simplify control of audio coverage and reduce interference.’

In each of the 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, supporting the A&H Harmony UI while 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.

The stadium uses136 EAW loudspeakers driven by 34 Dante enabled Powersoft Quattrocanali 4804 DSP+D amplifiers.

‘The catwalk in the stadium has a weight limit for loudspeaker installations, so we had to take that into account when creating the system,’ Yongjun says. ‘We also needed to consider the durability of any products we put out there, and in particular ensure that the loudspeakers were weatherproof, lightweight, precise and with a high output.

‘With reliability as the most vital requirement, choosing amplifiers that were up to the immense task of driving this system was crucial,’ Yongjun says. ‘Powersoft amplifiers have an incredible reputation, we knew them to be highly efficient and extremely reliable, not to mention their immense power output, which made them the perfect choice for us.’

EZPro wanted to avoid potential failure throughout the signal path of the audio system, which is where Powersoft’s Quattrocanali DSP processing was vital. ‘The built-in DSP modules incredibly useful, like the advanced EQ, And with lengthy cable runs like the ones we used for this installation; the active damping control feature was also essential.’

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, the project’s technical designer. ‘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 set-up.’

For the diamond shaped gymnasium, sound reverberation presented another challenge, along with the need for the space to transform into a basketball court or an ice hockey rink when needed. For this area, EZPro opted for a combination of EAW RSX212L, RSX18F, RSX129 and VFM129i loudspeakers. Serving the system are three Allen & Heath digital mixers and two Symetrix digital processors.

‘The way these are organised provide acute direction of sound and reduce any diffusion into the bleachers by the stage, which improves speech comprehension in the venue,’ Yongjun says. For these 70 speakers, a single Quattrocanali 4804 DSP+D is able to provide ample power and high-quality audio.

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

The hall features 30 EAW loudspeakers powered by eight Powersoft 4804s DSP+D amplifiers, along with two Allen & Heath digital mixers and two Symetrix processors. ‘The amplifiers play a significant role throughout the entire venue,’ says Yongjun. ‘Main signals go directly into the amps with Dante cards before feeding the loudspeaker systems, which ensures the best signal quality. The amps are capable of detecting and switching channels automatically as required, whilst dealing with all the digital and analogue signals flawlessly.’

The system is supported by ArmoníaPlus, Powersoft’s system design software which has been devised to allow simplified control of complicated installations.

The software allowed EZPro to speed up the initial system commissioning phase, thanks to its speaker preset models, and has continued to be an essential part of the system control. With ArmoníaPlus, operators can quickly check if the amplifiers are online, their signal and temperature ranges, and they can monitor the speaker impedance, whenever and wherever required. ‘The clear and intuitive user interface of ArmoníaPlus is a crucial asset to the installation for daily system operation,’ Yongjun says. ‘The offline editing functions, quick set up and group control functions are extremely practical for the install.’

ArmoníaPlus allowed EZPro to visually represent the amplifiers in their locations, thanks to its customisation features. ‘The amplifiers located in the different rooms are replicated in corresponding zones, arranged in actual installation order. It’s invaluable for operators and makes controlling this complex system intuitive,’ Yongjun says.

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.

The installation process took just over a year, and was completed in July 2020. ‘Overall, we are really pleased with how the installation turned out,’ Yongjun reports. ‘Everything went exactly as we planned, and the delivery and final result have been commended by the client.’

‘The schedule was pressing, yet the sound system installation and commission were finished on time thanks to EZPro’s efforts,’ adds Zhou Jun, chief technical engineer of the stadium project. ‘Third-party experts were invited to approve the installation, and they gave high praise and recommendation to the installation. It lives up to the highest Chinese standard for fabulous technical performance, including max SPL, sound field uniformity and sound.’