Nexo Alpha System - Manual (Page 16)

α α α
P 16
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)
• At high frequencies, wavelength being short in relation to the size of the cabinet, the gain level is
smaller : no gain will be obtained for cabinets angled at their nominal coverage, maximum gain will be
obtained for n cabinets pointing in the same direction. Therefore, the gain will range from 0 to 3 dB per
doubling ; for n Alpha M3, M8, EM or EF :
0
≤ L
GSPL
(1kHz-10kHz)
≤ 10 log
10
(n)
• The Alpha TDcontroller Array EQ is derived from array measurements to compensate the array coupling
effect.
20 100 1k 10k 20k
-10.00
-8.000
-6.000
-4.000
-2.000
0.0
2.0000
4.0000
6.0000
8.0000
10.000
AlphaTD Controller Array EQ / Frequency (Hz) / Gain (dB)
Alpha TDcontroller Array EQ
3.3. SPL V ERSUS D ISTANCE
In open-air conditions, the level of sound at a given distance is related to the following parameters :
• the size and the geometry of the source, which determines the shape of the sound wave (spherical,
cylindrical, plane) ;
• hygrometry and temperature : viscosity of the air and thermal conduction cause an energy loss
increasing with frequency. This phenomena is referred to as excess attenuation.
3.3.1. S INGLE C ABINET
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