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ALPHA ARRAYS - SOME BASIC RULES
ALPHA SERIES USER MANUAL V1.0
DATE: 14/01/00 18:27
Single Cabinet
Lp(1m) being the sound pressure level at 1m, the level at a distance d (in meters) is given by:
Lp(d) = Lp(1m) - 20 log
10
(d)
•
Single Cabinet SPL versus Distance
For example, if the level measured at 1 meter is Lp(1m) = 100 dBSPL, the level at 2 meters will be
94 dBSPL, 80 dBSPL at 10 meters and so on. Note that under these conditions of small source
and open air, the sound pressure level will be decreasing by 6 dB when doubling the distance.
Straight Vertical Array (long throw)
Some open-air applications might require loud level on a wide frequency range at a long distance.
It is then recommended to stack a large number of Alpha M3/M8/EM vertically. Up to a determined
distance - function of the frequency and the height of the stack -, the sound wave is cylindrical
(3dB/2d); it becomes progressively spherical (6dB/2d) above that distance.
•
Transition from cylindrical to spherical wave front
1
10
100
60.000
70.000
80.000
90.000
100.00
110.00
Sound Pressure Level (dBSPL) / distance (meters)
1
10
100
60.000
70.000
80.000
90.000
100.00
110.00
Sound Pressure Level (dBSPL) / distance (meters)
