Nexo Alpha System - Manual (Page 17)

α α α
P 17
USER MANUAL
VERSION :1.01
DATE : 06/10/10
1 10 100
60.000
70.000
80.000
90.000
100.00
110.00
Sound Pressure Level (dBSPL) / distance (meters)
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.
3.3.2. S TRAIGHT V ERTICAL A RRAY ( 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 wavefront
3.3.3. P LANE R ECTANGULAR A RRAY
When both dimensions of an array are greater than the listening distance, the energy is spread over a
plane surface : there is no attenuation with distance. As the listening distance increases, the sound wave
becomes cylindrical (-3dB/2d), and then spherical (-6dB/2d)
Transition from plane to cylindrical, to spherical wavefront
1 10 100
60.000
70.000
80.000
90.000
100.00
110.00
Sound Pressure Level (dBSPL) / distance (meters)