Meeting Topic: Line Array Technology Made Plain
Moderator Name: Dan Mombourquette
Speaker Name: Paul Bauman - Director, Tour Sound Product & Application Engineering with JBL Professional
Other business or activities at the meeting:
Dan Mombourquette greeted everyone. He thanked PA Plus for hosting the event and Soundcraft for sponsoring it.
Blair Francey announced three upcoming meetings: January sees Martin Pilchner discussing tuning your studio, February has the new Noble St. Studio tour, and March Tim Dolbear from Magix will talk about the Sequoia software.
He also provided a reminder for membership renewals.
Meeting Location: PA Plus 160; Bartley Street; Toronto, Ontario - Canada
This event was an excellent complement to the recent tour of the Air Canada Centre which took place in November (2010). Attendance, and interest, was high, despite the time of year.
Mark Radu, Systems Engineer at PA Plus, opened the meeting with a brief introduction of the presentation. He outlined some of the advantages of the new technology, such as the Smaart Amps with its on-board DSP. He spoke of his association with Paul Bauman for the past five years, and of the projects on which they have worked together.
Mr. Bauman then spoke of the general theory of line array technology. Using visual aids, he presented some models, showing how and why they work in a line array, and on a system level, how they are amplified and controlled by software. Accompanied by many photos of components, technologies and actual installations, this was a very intensive presentation, but laid out quite logically.
A line array is a column, or row, of sound sources. A column of speakers provides the same directivity in the horizontal plane but in the vertical plane you start to have some pattern control. Typically with column speakers the goal is to have control over the speech bandwidth in order to have intelligibility in highly reverberant spaces such as a church.
A line SOURCE array is one that, as its name suggests, approximates a continuous line source. The more continuous the source, the broader the spectrum of the operating bandwidth, and the more precise the vertical pattern control is. You also get full audio bandwidth performances, extended near field, and if the speaker components are modular, the angle between the speakers can be physically shaped, to match the coverage to the specific audience location. You can optimize the SPL distribution and frequency response if and only if it's properly focused on the audience. It's a precision 'tool' and it's not as forgiving as 'point-and-shoot' type speakers.
A line source will exhibit only 3 dB of attenuation per doubling of distance, as opposed to 6 dB which is typical of point source systems.
One of the highlights during the evening was the demonstration of the System Architect software which will display the audience coverage achieved in terms of SPL distribution and frequency response by entering various values for the speakers in the array such as gain, eq and delay. Its main goal was to obtain coherent summation over a well defined coverage region.
Naturally, practical elements weigh into the software such as the angle and weight distribution of the array, and individual speaker angles. You can also enter data like air absorption, temperature and humidity and see the effect they'll have on things like high frequency response.
A Variable Curvature Array will give better audience coverage, with less attenuation with each doubling of distance. The JBL VerTec system can generate a cylindrical wavefront, obtaining the full benefit of the increased directivity, provided the system is properly focused. To this end, JBL manufactures their own speakers rather than using off-the-shelf OEM components.
During the break, music was played on a system including the JBL VerTec VT4886 and VT4883 subcompact system, powered by the Crown VRack.
The night finished first with photos of real world installations including the Gibson amphitheatre, Club Nokia, Nokia Plaza, Regal Cinema (which Mr Bauman recommended highly), Nokia Theatre, Nine Inch Nails 2008 Tour, Rock in Rio, and Walt Disney Concert Hall to name only a few.
Finally more sound demonstrations closed the evening, this time at full volume.
In response to questions, Mr Bauman felt there is still some room for point-and-shoot but overall it's not a very efficient system. He liked System Architect because it's predictable, it gives vertical pattern control, among other things. The system seems complex at the onset, but once everything's understood, it's 'simple'. It gives better results, saves time, eliminates trial and error — set it up right once, focus it and everything is pretty much done - "it's almost plug and play". Its why training is offered.
When a question regarding how individual eq figures are arrived at for best audience coverage, Mr Bauman gave a sneak preview of a work in progress (with no guarantees it would work!) of software called Tour Manager, still in beta, projected for spring.
In response to a question regarding the iPad app, Mr. Bauman replied that it's now being qualified by Apple, and hopefully will be released in time for the N.A.M.M. show.
Blair Francey thanked attendees, PA Plus, JBL and Soundcraft Canada.
Written By: K. Machat; F. Lockwood
