JBL VRX932LA - Manual (Page 5)

5
AMPLITUDE SHADING
Amplitude Shading
Amplitude shading is a technique that allows the coverage pattern of a loudspeaker array to be shaped by
adjusting the relative acoustic output of some of the devices in the array. Most often, array shading involves only
the mid and high-frequency sections of the array. In a simple system consisting of three VRX932LAs, the lower
speaker (which covers the nearest listeners) may have its high-frequency output reduced. At the same time, the
upper speaker may have its high frequency output increased. The overall sound-power in the room is unchanged
but the distribution of acoustic energy to the audience is far more uniform. Amplitude shading of a VRX932LA
array may be accomplished in passive or bi-amplified systems.
Array Configuration Selector (ACS)
In passive mode, the Array Configuration Selector may be used. The -3 dB position will typically be used for the
speaker(s) in an array that are covering the nearest listening area. The +3 dB position will be used for the speak-
er(s) covering the more distant areas; or to compensate for the low-frequency build-up resulting from mutual cou-
pling of multiple woofers in an array.
Short Throw (-3 dB) Long Throw (+3 dB)
Medium Throw (0 dB)
Frequency Response
The frequency repsonse graph represents measurements from a single VRX932LA speaker, applying the three
different ACS settings: +3dB, 0dB, -3dB.