MTD 112 10 06/97
Both available SPL figures and low frequency extension can be enhanced with the use of
subwoofers, which can be physically separated from the MTD 112 enclosures because of a
low crossover cutoff frequency, i.e. 110 Hz. Nevertheless, care should be taken during the
subwoofers installation to avoid phase cancellations.
Ideally, the subwoofers should be grouped together in a central stack or array, and fed with
a summed mono signal. Provision for mono summing of the subwoofers signals is provided
by the MTD 112 LLCa controller.
c) SIDE FILL APPLICATIONS
The MTD 112 system can be used as a side-fill monitor, preferably with a SB 115
subwoofer enclosure. In this case, the optimum setup is to install the MTD 112 enclosure on
top of the SB 115, both in a standing position.
There should be provided an electronic crossover for the subwoofer, as the "SUB" output of
the LLC controller is mono, summing the two signals fed to its inputs.
For a proper phase coherence at the crossover frequency, the front panels of both
enclosures shall be in a vertical alignment.
When used in a side-fill application without a subwoofer, the MTD 112 should be raised
above the ground to be at a correct height. Stand mounting can be provided, but any stable,
non-resonant mechanical support can be considered.
d) DELAY LINE SOUND REINFORCEMENT
It often occurs that a complete coverage of an audience requires the location of
loudspeakers near some areas of the audience , rather than near the stage. A proper sound
localization can be achieved in this case by delaying the signal feeding the loudspeakers
which are the closest to the audience. The rule is that the first sound wave reaching any
listener must be coming from the stage.
Delaying an MTD 112 system can be achieved with accuracy. Some delay lines are
provided with direct distances displays, easing the adjustment of the delay. In this situation,
you should verify the temperature, such metric displays being valid normally for 20° C.
Provision exists on some units for actual temperature data input. You should check this
during the setup.
NOTE: Speed of sound in air
c = 331.6 + (0.6 t) in m/s. with t = temperature of air in ° C
For its compact size and its wedge shape, the MTD 112 enclosure allows unobtrusive
sightlines when installed in the concert hall, particularly when underbalcony location is
required.
No subwoofer should be used for delay line sound reinforcement.
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