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1. What is the correct application for a Line Array? 2. For a fan shaped theater should we ask for Left & right or Center cluster?
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Because every individual venue presents its own unique acoustic challenges and requirements, no one system type is the right choice for all venues.
First, a line array is basically an assembly of specialized boxes hung one under another. The basic concept is that a line array will have a fixed horizontal dispersion and a narrow vertical dispersion. Most of these systems require a minimum number of boxes for the line array effect to work. That could be a minimum of 4-6 or more boxes required hanging in a line.
A line array is not specific to live or loud audio, it is just a type of system that uses a line of boxes to achieve a specific coverage pattern.
Depending on ceiling height, and hang location, a line array may not work in a center cluster position. Also, depending on the room width, and hang location, a center cluster line array may not cover all the audience areas. Additional fill speakers may be needed.
A line array is not a be all-end all solution to PA problems, especially in installed venues.
As far as your building goes, the main questions to ask are:
<b>What rigging locations are available?</b> Is it feasible to hang a large center cluster, or would the weight of a large PA have to be distributed across the ceiling
<b>What are the aesthetic considerations?</b> Will you be happy with visible speaker clusters, or a long line array? Will the speakers be covered or mounted behind a baffle? Will the weight of a baffle or other speaker hiding scrim make any location to heavy?
<b>Can additional fill speakers be used in the system?</b> Do all the speakers need to fly from the ceiling, or can some smaller delays be mounted on wall, or under a balcony?
<b>Does the room height, or shape lend itself to one system type over another?</b> Is the room to short in height for a line array? Would a line array obstruct any sight-lines if used? Are their future plans for large Video screens, other A/V or Lighting that need to be addressed in the hang locations now?
<b>Is the room acoustically treated, or will additional acoustic treatment need to be made to use a large PA successfully?</b> Will the addition of a specific type of PA lesson any acoustic treatments required?
Then you need to ask the contractors who are bidding to show you successful uses of what they propose in similar sized/shaped rooms as yours. This is very important, as it shows two things. One, that the proposed system type will fit your venue and needs. And two, that the contractor has experience in designing and installing these type systems.
The biggest problem with most contractors is they they seem to recommend only what they sell. If they only sell a limited number of brands, then you the customer may not be getting actually what you need. a way around this is to use a Design consultant that is separate from the install contractor. Have the consultant design the best rig for the space, and then shop out his specs to installers. That way you are not limited to only what brands an installer has.
As for me, the perfect installed system is one that provides adequate coverage to all audience areas, without putting more wasted energy into the rooms.
I would think that for your wide fan shaped room that a system of controlled dispersion boxes (like SPLs TD1s or Runts) or similar in a central cluster or Left/Center/Right clusters would fit the bill better than just slapping a few line arrays in. Additional subs could be flown or placed at the ground level (or even hidden under the stage, in walls, etc)
Oh, and one last thing, bigger is not always better. Many contractors spec an 18" subwoofer because they think that a larger cone or bigger box will provide better bass. That is far from the truth. Our LAB Subwoofer project right here on PSW uses 12" drivers, and outperforms just about every double 18" cabinet. There are a lot of subwoofer systems that are way better suited to installs than large bulky 18" boxes.
Meyer, and others have cardioid subwoofer. These cardioid subs focus their energy to the front, less energy to the sides, and even less energy still to the rear. This results in less bass leaking into areas where you don't want it (like on stage) and not bouncing off walls or other reflective surfaces.
In addition to cardioid subs, many manufacturers have subs with other pattern control and directivity. Some subs are small and can fly, while others may be large, but could be built into the building (like under the stage) so they are not visually apparent.
Craig Leerman