Meyer Sound M'elodie, Operating Instructions Manual

19

CHAPTER 5

Low-Frequency Design Strategies

While wave guides provide isolated control over various 
mid- to high-frequency coverage areas, the low-frequency 
section of a M’elodie array still requires mutual coupling 
— with equal amplitude and phase — to achieve better 
directionality. 

Low-frequency directionality is less dependent on the array’s 
relative splay angles and more dependent on the number of 
elements of the array. At low frequencies, the more elements 
in the array (the longer the array), the more directional the 
array becomes, providing more SPL and headroom in this 
range. The directional control of the array is achieved when 
the length of the array is similar or larger than the wavelength 
of the frequencies being reproduced by the array.

Optimizing and Equalizing the Array

Once the design (number of elements, vertical splay angles 
and horizontal splay angles between arrays) has been 
designed using MAPP Online Pro, you can effectively 
optimize the array by driving it with multiple equalization 
channels, or zones. Typically arrays are divided into two or 
three zones, depending the design and size of  
the array.

To optimize and EQ the array, different strategies are  
used for:

■ 

High frequencies 

-   long throws 

-   short throws 

■ 

Low frequencies

High-Frequency Equalization Strategies

For the far field, air absorption plays a critical role. The 
longer the distance, the greater the attenuation at high 
frequencies. In this zone, high frequencies generally need 
a correction to compensate for energy lost over distance; 
the correction needed is usually proportional to the distance 
and high-frequency air absorption. 

In the near- to mid-field, the air absorption is not nearly 
as critical; in this zone, high frequencies need little or no 
additional correction. 

TIP:

If your M’elodie line array uses a third 

zone for short throws, high frequencies there 

may need to be attenuated to more appropriate 
near-field levels. 

Low-Frequency Strategies

Although the array can (and usually should) be zoned 
for implementing different equalization curves for high 
frequencies, 

similar or identical

 equalization should be 

maintained in 

all

 the low-frequency filters. Different low-

frequency equalization settings in the same array will 
degrade the desired coupling effect. 

For the same reason, severe gain tapering is not 
recommended for line arrays, since adjusting various zones 
with an overall amplitude control for each results in the 
following: 

1.  The length of the line array column is effectively 

shortened 

2.  Directionality decreases at low frequencies.

3.  Low-frequency headroom decreases.

Figure 5.2 shows a series of MAPP Online Pro predictions 
based on an example M’elodie system design. Please 
note that small vertical splay angles on the upper part of 
the array are used to cover longer distances, while greater 
angles in the lower elements to increase vertical coverage 
for shorter distances. 

Figure 5.2. 

MAPP Online Pro plots (above right) illustrate the vertical 

directivity characteristics of the array (above left), with a section view of 

the venue superimposed.

2 kHz

4 kHz

1 kHz

500 Hz

250 Hz

8 kHz

125 Hz