Making A Grand Stand

Opened in 1997, North Harbour Stadium is home ground for North Harbour side in New Zealand’s Mitre 10 Cup provincial rugby union competition. It also regularly plays host to rugby union, soccer, rugby league, and baseball games. Situated in Albany, North Shore City, it has even been the venue for a few rugby union and league internationals. Multiple function spaces for events catering for between 5 and 1000 people keep the venue busy during the week.

The main grandstand is on the southern side and the roof spans 180m with several tiers of seating, accommodating up to 12,000 people. The speaker system under these tiers was installed about 15 years ago and had suffered badly in the weather since. By 2020, it was seriously underperforming and in need of refurbishment. 

Matt Oliver of Livewire Audio Visual, in-house AV supplier for events at the stadium, was asked by venue management to quote on upgrading these speakers. As he says: “the old system was literally falling out of the roof and some of the speakers weren’t even working. There was little intelligibility on the ones that were.” Much of the cabling was also degraded, so they made the sensible decision to replace all of that as well. 

The seating tiers might be a good way to accommodate patrons for sporting events, but the hard concrete surfaces and awkward angles make audio reinforcement a challenging proposition. Contending with disruptive reflections and prolonged exposure to the weather were key constraints in any upgrade path.

TEAM STRATEGY

Matt got together with Kelvin Colling, General Manager of NAS NZ, and they worked through the best options for this situation. After considering several alternative configurations, they revisited the original scheme of employing long rows of speakers to get even coverage across a tricky space. They used 26 inDesign ID-mh158 WH horn loaded loudspeakers, spaced about 5m apart. The ID-mh158s “sound good and do a reliable job” according to Matt, “and they are better than most else available at that price point.” 

Kelvin and the NAS team knew some of the history of the original install and that knowledge was put to good use in recommending the new system. “The key was to put in more speakers running at a lower level. That gave us the ability to improve intelligibility without pushing the speakers too hard. We ended up putting in more than were there originally.”

Matt had looked at the distances involved and “knew that we had to do a 100V line system.” The long runs of IDs are powered by a single Ashly nX 1.54 power amplifier running in High-Z output mode. Being able to use just one amplifier is a huge plus in scenarios like these and allowed room in a tight budget to get the inDesign boxes included. Cabling from the amp to each end of the grandstand ran up beyond 120m. Livewire managed it with one conduit run in each direction from the rack location. Matt used Maximum Cables spc013 two core cable to keep it looking neat where exposed while keeping the signal strong.