Line Array
Definition
A line array is a vertical column of closely coupled loudspeaker elements that behaves as a single tall source. In its near field, it radiates an approximately cylindrical wavefront whose level falls by about 3 dB per doubling of distance, against 6 dB for a point source. Beyond that zone, the level falls by 6 dB per doubling. The extent of the near field increases with the length of the array and with frequency. The splay angles between elements set the vertical coverage, and manufacturers provide prediction software, such as L-Acoustics Soundvision, d&b ArrayCalc or Meyer Sound MAPP 3D, to calculate them for a given venue.
In the field
Array angles are normally calculated in the manufacturer's prediction software from the room geometry before rigging. The upper elements, aimed at the far seats, use small splay angles to throw further, while the lower elements use larger angles to cover the front rows.
Related lessons
Sources
- Line array (Wikipedia) : front d'onde cylindrique en champ proche, −3 dB par doublement contre −6 dB pour une source ponctuelle · en.wikipedia.org
- L-Acoustics, Soundvision : logiciel de prédiction et calcul des angles · l-acoustics.com
- d&b audiotechnik, ArrayCalc : logiciel de prédiction des systèmes d&b · dbaudio.com
- Ballou, Handbook for Sound Engineers : lignes sources et champ proche