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In this incorrectly hung loudspeaker, consumer-grade components and eye bolts added inappropriately to the speaker cabinet are just a few of the problems that could cause this loudspeaker to eventually plunge to the sanctuary floor below.
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Some of the things that make this rigging situation correct and safe are: Engineered brackets are used for clean and safe attachment to the wood beams. All wire assemblies are properly terminated with swages and thimbles. All shackles use steel tie wire mousing to secure the shackle pin. All eyebolts are forged shoulder type. Pan and tilt angles on loudspeakers are easily and safely adjustable. No wire rope clips, ratchet straps, or quick links are used.
Overhead suspension (also known as “rigging” in professional circles) of loudspeakers is a task that many church audio installations have in common. Since rigging speakers can be both difficult and dangerous, it is surprising that “do-it-yourselfers” sometimes create and install their own rigging, unaware that they may be using unsafe methods and materials. Just because it may be physically possible to suspend speaker enclosures overhead without professional guidance or proper materials, that does not necessarily mean they are safe. Absence of a disastrous rigging failure may simply mean that the church has been lucky so far. People sitting under unsafely suspended speakers may be in danger of injury or death.
Generally, people don’t try to save money by building their own amplifiers. But sometimes there seems to be a perception that money can be saved by making rigging a “do-it-yourself” job. This idea may overlook some basic safety issues.
To begin with, the person responsible for administering the rigging project should perform their due diligence in planning and documenting the steps that will be taken from the beginning to the end of the job. This will facilitate an orderly procedure and minimize the impact of surprises along the way.
The church building’s roof structure should be evaluated by a professional engineer for its ability to support a load. Look for help from the best rigging contractor available. A structural engineer, licensed in the jurisdiction of the job, should confirm that a particular structural member is capable of supporting the load. In other words, make sure that it will be safe to hang speakers there in the first place. The load bearing capacity at each attachment location in the roof structure should be documented as safe by the engineer. In addition, any assembly of Unistrut or other parts used for loudspeaker suspension should have a drawing stamped by a professional engineer, confirming that it will be safe to suspend that assembly.
It is important to choose speakers that are designed for overhead suspension. They are built to take the stress of hanging in the air and have certain spots on the enclosures, or “rigging points”, where suspension hardware can be safely installed. They also have internal metal bracing, so that the bottom of the speaker will stay attached to the top of the speaker. The speakers should also come with technical data essential to safe rigging. This data includes the location of the center of gravity, rigging points, and full geometry. Choose a manufacturer who provides this technical data when the speakers are purchased. Sometimes it may be possible to buy speakers without this data being automatically provided, and then time is spent by the customer on trying to track it down. Speakers that are intended for overhead suspension, and that automatically come with all of the above technical data, will be easiest to use.
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Kathy Patrician has worked in the audio rigging industry for 14 years, and in the audio equipment business for several years before that. She is a co-owner of an audio rigging hardware design and manufacturing company, Polar Focus. For more information, visit the company website at www.polarfocus.com. .(JavaScript must be enabled to view this email address)
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