CHAPTER 5

Using Meyer Sound Processors to Drive and Optimize the Array

The Galileo 616 loudspeaker management system and the LD-3 compensating line driver are specifically designed to allow you to follow these optimization strategies:

■The array can be divided in zones.

■The atmospheric correction capabilities of these processors compensates for the air absorption of the air at high frequencies. Each section allows different correction settings according to the distance of each section’s intended coverage.

■The processors effectively manage low-frequency build- up in the array and correct all zones of the array with the same correction at low frequencies.

In addition to their unique atmospheric correction for high frequencies and their low-frequency compensation capabilities, these Meyer Sound processors feature:

■Low-pass and high-pass filters with minimal phase shift that can effectively integrate subwoofers with M’elodie arrays.

■Robust output line drivers that easily drive Meyer Sound self-powered systems over long cable runs.

Figure 5.4. The LD-3 air attenuation compensating line driver

NOTE: The MILO or M1D setting in the LD-3’s Array Correction section can be used

effectively with M’elodie, adjusting the Array Size for the equivalent length of the array. For example, the length of 6 M’elodies is approximately equivalent to 8 M1Ds or 4 MILOs. The size relationship is not exact, so you may need to adjust the Array Size number up or down for the best result.

The Galileo loudspeaker management system is a hardware/software system providing all of the facilities required to drive and align sound reinforcement systems, and offering fixed low latency across each output. The Galileo 616 is a 2U, 6-input/16-output fully digital matrix processor. Compass software provides comprehensive control of the Galileo 616 via a graphical user interface (GUI) running on a remote computer, or controlled directly from the processor front panel.

Designed as the perfect complement to Meyer Sound’s self-powered loudspeakers and interfacing directly with the SIM 3 audio analyzer, the Galileo system includes digital delay lines as well as digital implementations of popular features developed over years by Meyer Sound for its acclaimed analog processors, including air absorption compensation filters, array correction, and equalization from the CP-10 and VX-1.

Figure 5.5. Galileo 616 Loudspeaker Management System

For more information on Galileo and its Compass control software, please visit www.meyersound.com.

Using Digital Signal Processors

Full-range signals may be applied to Meyer Sound’s self- powered loudspeakers because they have built-in active crossover circuits; external crossovers and digital signal processors (DSP) are optional and should be used very carefully due to phase shifts that can cause cancellations.

If DSP is used, all zones in a M’elodie array as well as the subwoofers should be fed from the same DSP in order to keep their delay time the same. Otherwise you may experience phase shift differences among the M’elodie loudspeakers in the array and between M’elodie loudspeakers and the subwoofers. In addition, you should verify the delay time between channels: Some DSPs may develop channel-to-channel variations in delay when the DSP is near maximum throughput, which becomes more likely as the number of filters the DSP is using increases.

In no case should a filter higher than 2nd order be used to optimize the interaction between the M’elodie array and the subwoofers. The additional phase shift introduced deteriorates the impulse response and higher roll-off does not improve crossover interaction.

TIP: Some filters on the Galileo and LD-3 are parabolic filters with minimal

phase shift, designed specifically to optimize the interaction between M’elodie and subwoofers; most commercially available DSP devices have no presets to emulate these minimum-phase parabolic filters.

In addition, if the loudspeakers are going to be driven directly from the DSP, verify that the outputs of the processor have the driving capabilities to drive the total load presented by the loudspeakers connected to it. Please refer to the Audio Input section on page 11 of this manual.

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