Geo T launched in Australia

The big thing in PAs is the line array. Now Nexo have come up with a new concept. How does it work? John Grimshaw investigates.....

When it comes to high end PA systems, it seems that the average touring artist demands the latest technology to adorn their concerts. Having listened to the PA behind the most recent Powderfinger tour, it is entirely possible that every touring artist and his dog will want to try out the new Nexo GeoT system.

That certainly is the hope of Bruce Johnston. His company Johnston Audio Services is one of the few PA rental suppliers for the brand. When we caught up with Bruce at the recent Powderfinger concerts in Sydney Entertainment Centre, he was keen to talk about his new system.

Bruce has been involved with big audio for many years, and is one of the 'nice guys' of the industry. He is certainly known as the FOH Engineer for Oasis, which was when his association started with the Nexo brand. It happened in Europe where Nexo is based. Oasis was touring the area, and Bruce got the opportunity to drive the Alpha system during a series of five Oasis gigs. He said that the sound just got better and better each night as he got used to the system. He was also getting comments from the management like, "Geez, the vocals were clear tonight".

The other things that intrigued Bruce about that original system was that you could fit 16 boxes in a row on the truck, and each one only weighed about 45kg. Back in Australia, Bruce decided to buy an Alpha system.

He has been quite busy ever since with numerous FOH engineers specifying a Nexo system for their events.

The technology and quality behind the speakers that originally brought Bruce into the Nexo brand continued to evolve - and now we have the Nexo GeoT.

This is not really a line array system - though it does look like one. The Nexo website describes this as a Tangent Array system. Where a line array is designed to place the point source of the audio in a single plane, as well as controlling the directivity of the audio, the Tangent Array allows a system engineer to create the effect of a very small single point source for an entire array. This (and some other innovations) has led Nexo to increased intelligibility and a significant reduction in phase distortion.

The Nexo website goes into significant detail as to how this works for those propeller heads out there that want to really understand the physics of the system. For everyone else, pictured on the left is the simple version.

If you imagine your speaker driver as the point source of audio within the speaker cabinet, the acoustic pressure wave (the audio) that is emitted by the driver is aimed at a specially curved hyperbolic reflector.

This curve redirects the audio out the front of the enclosure, simulating the 'virtual' position of the driver behind the box.

Using this design, as well as their own coupling, directivity, phase control and hypercariod subwoofers, Nexo was able to create the Geo S system. It was this smaller system that allowed the Wiggles touring audio to go from a Semi-trailer to an 8 ton truck.

The Nexo GeoT is the second generation of this technology - and the improvements are significant for both acoustic response, power output and ease of physical handling/ installation. When we visited the Sydney Entertainment Centre at 10am for the Powderfinger bump in, the PA speakers where still cased up (yes, they are small enough to actually need road cases), and being unloaded from the truck. The riggers had kindly located the required two chain motors per side for FOH PA.

The time was 10:08 and rigging the OP side stack started... The top plate is hung on the two chain motors, the speaker cables are taped to the top plate and the first opened road case is wheeled into position.

Four locking pins are used to attach the integral rigging plates on the first box to the top plate. Up go the chain motors.

Each subsequent PA box is then wheeled into position, locked in place and lifted out of the road case base by the motors. The final boxes in the array are smaller - to cope with the very short throw, and are set at a much steeper angle on the pre-drilled side plates.

Once all the boxes are in position, the 'kelping bar' is attached. This is used to give the array the perfect required angle to the hang.

Adjustments are made and the angles were finalized at 10:23am. The rig is flown out and set at its trim height by 10:31am.

The two crew it took to rig this system then walked off to do the other side. 23 minutes from nothing rigged to the system in position at trim height. Not only that, the entire thing was rigged within the footprint of the hung array - no more pushing other equipment and chairs out of the way to pre- rig the PA as a train along the floor before it flys.

At Powderfinger the system engineer, Drew Menard, had the trim height set high. Very high. It was way above the height of the lighting rig. This was something that the proprietary Nexo software told him to do, because at first glance it just looks wrong. In fact when you walk in the see the show, it looks like there is no sound system at all!

However, any skepticism that was had during the bump-in is quickly eliminated with the system is run up and the sound check starts. During the show, this writer had the opportunity to walk around the entire room. From the back row of the stadium all the way to the stage, I walked around, critically listening to what the system was putting out.

The system sounded extremely uniform throughout the room - from the back row to the front of the stage the sound felt like it was running at the same level. In fact it was probably loudest on the walkway that rings the room between the upper and lower seating banks, right behind the mix position.

The gig shot below was taken from this walkway - the loudest point in the room!

It was certainly loud everywhere but more importantly, as I walked around the room, the only time I could discern a shift in the phasing and the quality of the sound was when I was starting to move alongside the stage - an area covered by separate fill speakers. Even then, the quality remained high from the Nexo Alpha speakers used to fill the sides on either side of the stage.

One of the more surprising discoveries of the system was first pointed out to me by Bruce Johnston. If you stand a few meters in front of the sub woofers that were placed on the deck in front of the stage, it sounds like they are full range speakers. While this is definitely an acoustic illusion, the effect is very real - that despite the fact that the main PA speakers are trimmed at a very high position. You certainly do not feel like sound is landing on you from on high.

So there you have it, a very punchy, loud system, with excellent bottom end. No phasing problems that I could find, easy to rig and small to transport. What more could you ask for. The system used at Powderfinger was sitting on Camco amps, matched to the speaker power, and these amps were not working very hard at all. The impression was that you could have probably run the system at AC/DC levels without too much trouble. Wow!

There is already a great deal of interest from many in the industry wanting to use the system they are raving about in Europe.

Article from January 2004 issue of CX Magazine