Arraying

The M3D can be flown in lines of up to 16 cabinets or stacked on the ground. Multiple columns can be arrayed horizontally for wider coverage. When arraying columns horizontally, arrange them at a 50° - 90° angle to one another with the rear cabinet corners as close as possible (if practical, the corners should touch).

The ideal application for the M3D is as a straight line array for long-throw coverage. Conventional Meyer Sound Self-Powered Series systems, rigged under the M3D array or stacked on the ground, may then be used to cover the near field. This configuration yields optimum sound quality over the full coverage area.

The M3D’s QuickFly™ rigging system also permits splaying cabinets from 0° to 5° in 1° increments. Thus, you can create a gently curved array to widen the vertical coverage. When doing so, depending upon the array configuration and the geometry of the venue, you may elect to use amplitude tapering to assure an even sound level across the coverage area. It’s also advisable to equalize the long-throw and medium-throw sections of the array separately to preserve consistent sound quality.

Use With Subwoofers

The M3D implements the same low-frequency directional technology that Meyer Sound pioneered with the PSW-6 Cardioid Subwoofer. It’s important to understand how this technology works when adding subwoofers to an M3D system.

Like the PSW-6, the M3D employs a pair of rear-facing 15-inch cone drivers. These drivers are driven by a sophisticated circuit that introduces frequency-dependent delay to cancel the back wave of the dual front-facing 15-inch drivers over a broad range. The result is consistent 90° coverage down to 35 Hz.

The technique affords great advantages in controlling onstage bleed and reverberation, but it also makes the M3D incompatible with conventional subwoofers in most applications. The reason is that conventional subs are omnidirectional over their entire frequency range. If they are placed anywhere near the M3D array, their back wave will inevitably be out of phase with that of the M3Ds over some substantial frequency range. This can result in anything from unwanted cancellations to, at high power, driver destruction from excessive excursion.

Meyer Sound has developed a new companion subwoofer for the M3D: the M3D-Sub. It features the same low-frequency directional technology and can be flown in a line array adjacent to an M3D array. This is the ideal solution when using subwoofers with the M3D. Alternatively, you can use the PSW-6.

In certain cases – for example, where the M3D array is flown 15 feet or more away from subwoofers stacked on the ground, conventional subwoofers will work with the M3D.

Driving M3D Arrays

When configured as a straight line array for long throw, up to 16 M3Ds may be driven in parallel. A 16 cabinet array will present approximately 600 ohms impedance when paralleled, and can be driven by a Meyer Sound LD-1 or LD-2 Line Driver if it is placed reasonably close to the system. For long cable lengths, cable resistance may reduce the signal level significantly. In this situation, you can parallel the inputs of the line driver and use two channels to drive 8 cabinets each.

Curved arrays require amplitude shaping and DSP to control their low-frequency coverage. This will require that at least some of the cabinets be driven separately. Where an array incorporates both straight and curved segments, the inputs of the units in the straight segment can be paralleled.

A Real-Life Example: Zellerbach Hall

Zellerbach is a 2014-seat concert hall on the campus of the University of California at Berkeley. It features first-floor orchestra seating, a second-floor mezzanine and a third-floor balcony (see section view). There are therefore three separate coverage areas: two long-throw balcony shots and a broad area spanning long, medium and short-throw areas.

Recently, Meyer Sound held extensive listening tests and measurements of an M3D system at Zellerbach. To cover this large hall, Meyer configured seven M3D Line Array Loudspeakers and one CQ-1 Concert Series Loudspeaker in a single array comprising four integral sections (see illustration):

1. A pair of M3Ds, tilted upward 11° and splayed 2° –thus closely coupled for long throw – served the top balcony.

2. A similar pair of M3Ds, splayed 5° below the top pair so as to avoid hitting the balcony front face, covered the mezzanine.

3. Three M3Ds, all splayed at 5° for wider vertical coverage, served most of the orchestra seating.

4. The CQ-1, splayed 4° below the bottom M3D and separately equalized, covered the closest rows of seats.

A laser inclinometer aided in aiming the system components.

This system demonstrates how the M3D’s QuickFly™ rigging system allows for flexibly configuring and aiming long- and medium-throw array sections for optimal coverage. It also shows how other Concert Series products can be used for short-throw coverage, where the laws of physics pose unavoidable limitations on line arrays.

Driving the System

A Meyer MMP™ system handled signal distribution. The MMP (Meyer Matrix Processor) is a digital signal processing system designed expressly for optimizing the performance of Meyer Sound M3D Line Array Loudspeaker systems (the MMP is a proprietary research tool, and is not commercially available).

Multiple outputs from the MMP provided separate drive signals for the long-throw section (top five M3Ds), the medium-throw section (the bottom two M3Ds) and the CQ-1 frontfill section (see connection diagram). SIM™ facilitated equalizing each section separately with CP-10 Parametric channels, measuring with multiple microphones placed in the respective coverage areas. No amplitude shaping was required: the drive level to all cabinets was equal.

Rigging

An MTG-3D top plate suspended the array at center stage. Two bridles – one attached to the front pickup points and one to the rear points – connected the MTG-3D to a pair of winches. This arrangement facilitated tilting and aiming the array by simply manipulating the winches independently, with no need for a pull-back line.

Demonstrating the simplicity and effectiveness of the QuickFly rigging, a crew of three dismantled the array (after extensive listening) in about fifteen minutes. Custom caster rails, attached to each unit as it was lowered to the stage, eased handling and moving the speakers. Captive hardware was stored in conveniently located receptacle holes in each speaker’s integral rigging frame.