EAW N T L 7 2 0, Owner'S Manual

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7 ARRAY OPERATION
7 . 1 O v e r v i e w
The operation of an NTL720 Series system involves:
1. Understanding the principles on which it operates.
2. How to electronically configure it for a specific task.
7 . 2 E n g i n e e r i n g D e s i g n
7.2.1 DIVERGENCE SHADING
In almost any venue, there are significant differences in distance from the loudspeaker array to the
nearest and farthest audience members. The idea is to turn up the output level of the array aimed towards
the farthest audience members and then progressively turn it down for audience members closer to the
array. These differences in distance are accompanied by changes in the array’s vertical aiming angle.
To create the NTL720, divergence shading was originally modeled as a single, continuous, curved line
source. The average curvature at any point could be varied, as explained, to vary the output, providing
more output for longer distances and less for shorter distances. The engineering task was to design a
series of small elements that, when arrayed, would closely approximate the performance and the range
of vertical pattern control of the line source model.
Rather than using different amplifier levels to set the desired output variations along the array’s length,
a combination of the amount of curvature and the quantity of NTL720s determines the output
variations. A shallow curve means more loudspeakers are facing a given direction, putting out more
energy within a given vertical angle. A more radical curvature for the same number of loudspeakers
spreads the energy over a wider vertical angle, reducing the energy at any particular point. Simply put,
less curvature in a portion of the array turns the output volume up in that portion and more curvature in
a portion of array the turns the output volume down in that portion.
If you understand the above, you basically understand how a NTL720 array works. More specifically:
1. More splay at the rear of the enclosures turns the volume up (adds less curvature to the array).
2. Less splay at the rear of the enclosures turns the volume down (adds more curvature to the array).
3. More enclosures provide a greater vertical coverage angle.
4. Fewer enclosures provide less vertical coverage angle.
The NTL720 Array Wizard uses the above variables to determine the quantity of enclosures and the
variation in curvature along the length of the array that will optimize coverage for the audience
distances and angles the array must address. It actually works “backwards” by modeling the ideal
curved source for the user-entered parameters, then creating an array of NTL720 elements that most
closely approximates the performance of the ideal source.
7.2.2 GUNNESS FOCUSING™
Developed by the EAW engineering team (and named after its inventor, David Gunness), Gunness
Focusing uses DSP technology to eliminate the traditional characteristics of “honk” and “splashiness”
that can plague horn-loaded loudspeaker designs. The honk of a horn is normally heard in the lower
frequencies of its band pass, while splashiness (an attribute of compression drivers) is usually heard in
the highest frequencies and obscures the fine detail in instruments, such as cymbals.
Likewise, cone drivers have inherent resonances in their upper frequency range that result in
“muddiness” in the middle of the vocal range. These HF and LF behaviors combine to produce a sonic
signature commonly referred to as “coloration.”
The DSP algorithms specifically developed for the NTL720 correct these anomolies and resonance
problems, resulting in a sonic performance comparable to the highest quality, direct radiating studio
monitors but at a much higher output level.
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