10.11.09

Sounds of the city

AUTHOR: Inavate
The main entrance

The city of Beer Sheva in Southern Israel has recently enjoyed the opening of a municipal performing arts centre. Funded by the government, it is blessed with striking architecture, several performance spaces and one of the most advanced electroacoustic systems on the planet.

Way back in 2005, Barkai successfully tendered to install the AV systems for Beer Sheva’s newly planned performing arts centre. Why it’s taken almost four years to complete becomes apparent when you look at the photography that accompanies this story.

The ambitious nature of the winning architectural design lead to a number of construction challenges and delays to the project, which was finally completed in 2009.

During the intervening four years, things moved on in the systems integration market, to such an extent that the vendor of the originally specified electroacoustic system, LCS Audio, was purchased by Meyer Sound Laboratories. This necessitated a re-think by integrators Barkai, who eventually decided that the right course of action was to stick with LCS and specify Constellation, the system that Meyer Sound came up with built on the LCS technology.

However, we’re getting ahead of ourselves here. From the outset, Barkai considered the requirements of the hall. It’s a truly multipurpose venue, with the large concert hall needing to cater for orchestral, voice, small group and touring productions. They recognised that for major tours, the house system wouldn’t be used and so there was no need for an enormously powerful rig. It seats slightly over 700 people and in its primary role as a home for the Israel Sinfonietta, Beer Sheva massive power just was not required.

Consequently, Barkai specified a system built around Fohhn Audio’s AT and XT products. A left-centre-right system is built into the proscenium arch, consists of AT50 active models with bass reinforcement from XS4 powered subs. Back and side filling is performed by smaller members of the AT family, these are driven by Crown CTS amplifiers in racks beneath either side of the stage.

However, the fun part is the Meyer Sound Constellation system. This is divided into three key parts. Firstly 28 omnidirectional microphones, custom built for Meyer Sound, are suspended around the hall to pick up the ambient sound.

These signals are then processed in Constellation DSP units, before being fed back out to the accompanying active loudspeaker system. This is comprised of a combination of 40 MM4-XP point sources, 8 SUB UMS1Ps and 18 UPM-1Ps.

Shy Kadmon, Barkai’s technical director described the disposition of the speakers for the constellation system, and the logic behind it.

“We have MM4s in two rows down each wall. One is on the ground floor level, and a second mounted above the balconies. They are there to generate some lateral energy, mainly to simulate early reflections. Then we have 12 UPMs mounted in the ceiling of the hall, plus some of the subs. They are pointed down generating energy to represent reflections from the ceiling.

“Also we have more sub-bass speakers at the sides. They are invisible behind grilles above the balconies. There are four pieces on each side, plus two in the ceiling. That all adds up to a lot of bass energy.”

This was a key requirement of the design. When you are making an active acoustic system for an orchestra, you to need to generate a lot of low end – things like big kettledrums have to be very loud.

“On the back wall there are more MM4s to simulate more reflections. These small powered speakers are great for this application as they draw their power and signal directly from the racks – there’s no need for an AC outlet near the speakers.”

There’s also a massive amount of acoustic panelling in the space. Almost every surface is dampened in some way. I asked Kadmon to explain this.

“As a starting point you need that for one of these systems. You need to build a space that achieves something like [Rt] 1. It needs to be neutral. From there, using the electroacoustic system, you can increase it to 2 or even 2.5 seconds.”

Whilst the system in the main body of the hall provides the experience for the audience, of equal importance is that of the performers. There are two ways of approaching the stage-based component of an active acoustics system.

The first approach, is to create a complete acoustic shell around the orchestra, and make a multi-channel constellation system in it. However, that’s normally the approach for a full sized orchestra in a large concert hall. It requires a very large, expensive construction of a kind totally impractical at a venue such as Beer Sheva.

Another solution is the more minimalist approach adopted in this case. Behind the orchestra is a soundproof curtain acting as a back wall for the envelope. Then, mounted in the sides and top of the proscenium arch are more omnidirectional microphones. Finally the reflections for the orchestra are simulated by Meyer Sound UP Juniors fixed in the proscenium. (For more explanation on the function of an active acoustic system, see the box at the end of this article.)

The two systems (the Constellation, and the house audio) are linked by a shared Crestron control system and controlled via Ethernet.
A TPS2000 touch panel is located in the mixing position, and performs most control functions.

“It can switch the main PA on and off,” explains Kadmon. “It can also do this for each speaker individually for testing purposes. Then there is the paging system. The UI on the touch panel allows an operator to page any zone in the building, activate pre-recorded messages or make voice announcements. The message store is an Alcorn McBride AM4 player.

House audio is mixed through an Allen & Heath ML5000 desk, and there is a digital audio chain from the desk to Biamp AudiaFLEX DSP units in the racks. The Flex’s provide DSP for the delays in the house system as well as the Cobranet networking from the mixing position. Finally they perform a safety function, and are used to mute the house and Constellation systems in the event of a fire alarm or emergency PA announcement.

Joining the AudiaFLEX units in the equipment racks is a ClearCom intercom system and a Kramer video distribution amplifier. The DA provides a back stage monitor feed from a small CCTV camera, this allows the stage crew to view the stage from the point of view of the audience.

So how to judge the effectiveness of such an installation? The simplest way is probably to ask the man who makes most use of it. In this case that man is Doron Salomon, music director and principal conductor of the Israel Sinfonietta Beer Sheva. How did he become aware of active acoustic systems in the first place?

“I knew the ‘wonder’ of the system thoroughly before it arrived in Beer Sheva,” he said. “I have conducted in other concert halls before such systems were installed, and after, so I knew exactly what to expect.

“The orchestra is still learning to take advantage of the new sound, but by-and-large the musicians are more than happy. We are convinced that in due course we will be able to produce a better and more relaxed sound.

“A good musical instrument usually enlarges the possibilities of the sensitive musician and improves his sound, phrasing et cetera. The same can be applied to a good concert hall, and that is the most important contribution of the system to a classical orchestra.”

And did it live up to those expectations? “The system stood up to my expectations entirely. In fact, finally after some 30-odd years of making music in poor acoustic conditions, the Israel Sinfonietta can indulge in a decent symphonic sound. I would definitely recommend it to my colleagues!”