Specifications

TI 323 (6.0E)
20 - 36
Example of a vertical profile with the main axis of the
TOP loudspeakers.
1
2
3
45
Stage
Typical arena situation, showing the necessary horizontal
coverage.
6. System design
6.1. Basic planing
The first consideration is the combination of horizontal
and vertical dispersion angles needed to cover the
audience area from specific positions. These positions
should be chosen so that the system can give an
acoustic orientation towards the stage for as many
listeners as possible, while avoiding directing energy
at close boundaries or recessed areas.
6.1.1. Step 1:
First, the total horizontal coverage angle has to be
defined. Above a certain venue size it is
recommended to check the far field and the mid to
near field coverage requirements independently.
From this rough overview the number and the aiming
of 30° sectors can be determined. The coverage
angle per column for C4-TOPs and C3s should be in
the range between 20° and 30°, however choosing
30° sectors results in a seamless, interference free
horizontal overlap between columns (50° sectors for
C7-TOP columns).
In the following example of a typical arena, far field
horizontal coverage is needed for sectors 2 and 3.
Mid field coverage is needed for all five sectors. Near
field coverage has to be provided for sectors 1, 2
and 3.
Far field coverage in sector 1 should be avoided,
since the target area will also be covered by the long
throw component of the other main PA cluster. Due to
the large difference in the path length to this area
from each cluster a high level far field coverage for
sector 1 would cause a second arrival, or echo and
therefore decrease intelligibility dramatically.
Depending on the source program and the chosen
loudspeaker type, either a 5-wide or a 6-wide set up
with an additional column of SUBs to increase LF
throw would be suitable.
6.1.2. Step 2:
The audience areas vertical coverage profile and
throw distances have to be calculated, if necessary
independently for every column specified in step 1. To
achieve a uniform coverage and direct to diffuse
sound ratio the SPL variation should not exceed
± 3 dB over the listener area. If, for instance, the
distance to the farthest listener is 60 metres (196.9 ft)
and the distance to the closest listener is about
8 metres (26.2 ft), depending on the height of the
cluster, the resulting level difference is 17 dB.
Depending on the type of event, the average SPL can
be defined. From this, the type, number and vertical
angle of the cabinets can be determined. Using the
Inverse Square Law and the level increase due to
coupling, the SPL for various areas and the relative
levels within the columns can be estimated. The result
is a defined array of either C3 and/or C4-TOP
cabinets for the vertical coverage per sector. In the
example shown, sectors 2 and 3 use five C3 for far/
mid field coverage with 0°, 1°, 3.5°, 6°, 11° and C4-
TOP with 21° vertical down tilt. The column for sector
1 should not cover the far field, so the uppermost
TOP cabinet is deployed with a –10° vertical down tilt
to cover the back of the ground floor.