Ronald Goh, Managing Director of Electronics & Engineering Pte Ltd who was 27 years old when he was involved in the original National Stadium comments about the sound system at the new National Stadium, “After watching the World Rugby 10s that was held from 21-22 June at the new stadium and seeing how the sound system was used, I realised that this is the new age sound system. 40 years ago the sound system at the National Stadium was a Voice or Public Address system. Now it is a Disco quality sound system with sub frequencies going down to 25 Hz and literally hits you on the chest. Whenever, a goal is scored from either side, the soundman or DJ in this case, cranked up the sound level to enhance the cheering and built up the mood. In fact, at one point the DJ played the familiar disco song “YMCA” and got the whole crowd in the stadium standing up, swaying to the beat and acted on the Y M C A as it is being played over the main event sound system just like in a disco except that this is in a 55,000 seat stadium. The subwoofers did provide all the “oomphs” to get the crowd excited. What a far cry from the old stadium sound system and technology of 40 years ago. He adds, “At the end of the day we have provided a good world class sound system and it is up to the person using the sound system to make full use of the high power sound system to create the ambience to excite the crowd.”

Ronald is indeed very pleased with the EAW speakers. “In our business it is always location, location, location and then the choice of speakers. The EAW QX speaker systems are outstanding speakers that enabled us to meet the criteria set by the owners and consultants and I honestly doubt any other speakers would have met all of the criteria, especially on the speaker power output, clarity and its size.”

“There was already an operational criteria provided by the Sports Council on what their new sound system in the main stadium should be like. We are to meet their criteria and to provide a turnkey solution. They were obviously looking at cost as a key factor. They wanted to see if we can meet the criteria – price, weight, SPL. As the speakers would be installed under the roof, weight was a critical factor. We came up with the design to meet all their requirements.”

Ronald continues, “It is made possible because EAW has the right speaker. The EAW QX series speaker fits the bill perfectly. It has a 600mm square horn fitted with a high power mid and high coaxial driver/horn surrounded by 4 units of 12” bass speakers in a super compact enclosure. The winning factor was its clarity and the throw of the horn. But there were certain areas where we needed a double QX which is essentially a MQX model which has the same two co-axial drivers and two horns and aiming at a distribution angle served by a QX horn. They narrowed the horn so the sound can penetrate better. So for the lowest seating galleries which has the longest throw from the roof trusses, we used 3 MQX for each side of the grandstand to meet the Sound Pressure Level criteria at that distance of throw. MQX is a custom-made product that was designed specifically for stadiums and they had it which helped to meet the distribution power and at that height.”

Ronald provides a deeper insight as to the workings of the EAW QX system. “30 years ago a constant directivity horn will give you a frequency range of between 800 to 8,000Hz. Anything below that is omnidirectional. Whereas the EAW QX speaker is able to achieve good coherence and pattern control well into the low frequency range from 55Hz to 20,000Hz. This is made possible by having four Phase Aligned 12” low frequency transducers arranged as vertical and horizontal pairs that leverage beneficial interaction based on their spacing within the cabinet with minimal phase distortion throughout the whole frequency spectrum.”

There were other issues that E&E had to come to grips with and convince the project team to see it from their view and thankfully it all worked out well. EASE soft ware was used to decide on the location of the speakers which was all well. However Ronald points out, “The speakers were too high. I mean on paper it is okay but in reality it is different. It was 60m up. That means sound takes more than 200 millisecond to reach your ears when it is produced from the speaker. We needed to reduce that as much as possible and to keep the direct sound within the “critical distance” that is the direct sound from the speaker and the reflected sound from the ceiling and walls as far apart as possible. We managed to lower the speakers to a height of 45 meters so as not to interfere with the lights and other services. Lowering the speakers helps to bring a higher level of direct sound to the ears to improve on the overall clarity in a reverberant environment.”

Another aspect that mattered was regarding sound absorption or the reverberation coefficient in the stadium. “Sound travels and it gets reflected in all directions unless it is being absorbed by acoustic material in the space or its decay to 60dB and below. I always talk about the “car” and the “road”. We can design the best and fastest car, but we must have the road to complement the performance of the car. Likewise, the stadium interior and environment must complement the sound system for its best clarity. It was fortunate that the dome ceiling panels were absortive as they were perforated with the 50mm thick rock wool behind them, to isolate the interior from the roof panels.

Ronald adds on, “I was initially also concerned about the sound travelling from one side of the gallery to the other side. The stadium has four sides to it – East, West, South and North. My concern was if the reflected sound from speakers serving the North grandstand travels to the South grandstand, how much interference it will have on the intelligibility on the other side. It worked out quite well because of the seating incline and the absorptive ceiling, whatever remains of the sound travelling to the other side will be masked or drowned by the direct sound on the same side without affecting too much of the intelligibility of speech.”