Multipurpose Facilities. As the congregation grows, its members begin to look for a permanent home. They begin to think about the first phase of a building project. Good stewardship predicates that the building maximizes its utility because there are seldom enough funds to do everything at once. Therefore, many congregations opt to build a multipurpose worship space that can also serve as a meeting hall for meals, special programs and sport activities. I once visited such a place where the window casings were less than one standard volleyball width to prevent glass breakage when used as a gym, yet provided sufficient light for the Sunday morning service. So if a multipurpose facility is used and the speakers happen to be permanently installed, protection against flying objects would be advisable.

A small facility may occupy 900 square feet of floor space (30 feet by 30 feet or so) while most small spaces will hold around 100 to 150 people seated (50 feet by 60 feet, minimum). If the worship space has a regulation-sized basketball floor, the dimensions will be in excess of 55 feet by 110 feet, which is a area large enough to seat 450 to 550 people. This is no longer a “small church.” To promote a more intimate worship environment, many buildings adopt an architecture where the width of the building is approximately twice its length. In such cases, the speaker system is called on to cover at least 150 to 180 degrees of coverage. If a central cluster is used, this may require at least three systems with 60 to 90 degree coverage angles. Remember that we are discussing small, packaged systems here and not complex speaker arrays made of discrete hardware. In some acoustic environments, it may make more sense to use only two speakers on either side of the chancel area, as would be typically done in the portable case. In many cases, there is very little acoustic treatment in the room and, due to excessive reflections, it is too live. Simple acoustic treatment can be added to the room economically by suggesting the use of 3-inch-thick Owens Corning 703 fiberglass batts, covered with a suitable fabric and framed with a simple wood frame for placement on the walls. One must continually keep in mind that the operational budget of the church is probably between $50,000 and $250,000 per year, so funds are tight.

Your Role as Contractor

If you are lucky enough to be involved in the planning phases of the building project, suggest that sufficient sound, video and telecom cable be pulled while it is easy and inexpensive to do so. Whatever you do, don’t skimp on the microphone signal cable! There are, unfortunately, several brands of cables that exhibit up to a 15% to 20% unbalance in cable capacity from conductor to shield for the signal conductors due to cheap construction. If the cable runs are long, this unbalance in conductor-to-shield capacity will encourage RFI detection in most of the transformerless microphone input stages in the mixers currently on the market. Also of extreme importance is make sure that the sound system gets its own dedicated AC service that does not have a shared neutral with another service! Perhaps one of the most overlooked (and most misunderstood) technical issues is the proper AC power distribution for the system. Since the system will no doubt integrate both 3-wire safety-grounded equipment and 2-wire equipment with unbalanced inputs and outputs, proper AC power sequencing is essential. Again, see Figures 1a and 1b for the most basic concepts. It is essential that all of the small signal equipment derive its power from the same power strip. If there are remotely located power amplifiers, then a balanced I/O should be used between the mixer and the power amplifiers or powered speakers.

Designing and installing the system is the easy part. Determine the equipment requirements, work within the budget and close the sale. The single most important issue is realizing that, in almost every case, the sound system operator is a part-time volunteer, not a professional. Therein lies the root of most system problems. The field of knobs on the mixer often intimidates operators, as they really do not understand the system architecture. After all, if the wrong knob is turned, the resulting blast of feedback is very embarrassing. It is in the education and documentation phases of the project where the services of a professional will ensure successful equipment use. You are selling your service, not just equipment.

Be prepared to spend a fair amount of time on these phases of the project.

A common problem many church systems face is a not having a quick and easy “Return-to-Zero” initial setting chart to refer to when the sound system is readjusted by unsupervised helpers. The operator needs a map of the initial settings for the console and other equipment. This is one of the reasons why including a graphic equalizer or acompressor can be dangerous. If they are included in the system, some type of security cover must be used or the units will become misadjusted by either the church’s helpers or by the operational personnel.

Cal Perkins is the Technical Director at Mackie Designs. Contact him at cal@mackie.com.

S&VC
January 2001

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