How to place CCA-80 in loudspeaker layouts using the 6:1 Technique
This article explains how to use the "6:1" rule-of-thumb to quickly position CCA-80s in system designs.
The CCA-80 asymmetrical coverage pattern offers the added benefit of longer distance coverage from a single loudspeaker and a simplified method for determining the interval between CCA-80 locations in a sound system. The triaxial driver topology and asymmetrical MF/HF and LF waveguides project this unique pattern for paging loudspeaker systems.
Overview
Conventionally, point-source loudspeaker coverage can be approximated by the 3:1 Rule for coverage between the closest and furthest listener. Refer to the article linked at the end which discusses this method.
However, CCA-80 defined coverage permits a further distance between loudspeakers called the 6:1 Defined Coverage Technique. It applies to units all aiming the same direction for overlapping coverage.
Applying the 6:1 technique
Determining the approximate coverage
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Measure the mounting height above listening plane (ear height) = “H”
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Multiply “H” by Six
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6H = Coverage distance of one CCA-80
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Horizontal coverage = 2.3H
Extending the coverage area
To extend the coverage area with another CCA-80, locate the second unit at the 6H position. Signal delay should be applied in most cases to synchronize the acoustic arrivals of both horns for any listener positioned such that they can hear both horns.
This technique applies to EASE Focus modeling as shown below.
Notice that the Blue #1 Receiver flag and Red #3 Receiver flag mark the beginning and end of the Defined Coverage for a single CCA-80. In the Frequency Response, these two positions share nearly identical levels within the frequency range of the horn’s primary radiation. The Green #2 Receiver indicates the mid-point SPL which is within standard range for uniform coverage.
In this case, the Red #3 Receiver flag can be used to locate the ideal position for an additional CCA-80 to slightly overlap and extend the coverage of the first CCA-80.
Activate the Direct SPL mapping to see the total effect of both the forward and horizontal coverage.
Example CCA-80 positioning and coverage geometry, including Side View of venue:
Concurrent CCA-80 Coverage Zones with a second loudspeaker placed at Receiver Flag #3 (6:1 Rule)
Examples courtesy EASE Focus 3 by AFMG®
Applying to simple CAD layouts
An example with markup:
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The CCA-80 Defined Coverage can be marked with blocks in CAD.
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Use the links below for DXF and Sketchup formatted diagrams of the 6:1 Coverage Area (example images below).
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Scale the block by dimensioning either the vertical height (3D CAD technique) or the Horizontal 2.3H dimension.
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Copy and paste successive CCA-80 coverage zones using the 6:1 Technique.
Further reading
For precise location of CCA-80D arrays, see this article: CCA-80D – Designing with “Dual Cabinet Arrays”
To use the 3:1 Rule for layout with conventional point-source loudspeakers, see this article: The 3 to 1 Rule and R.15-3696