L-Acoustics MTD 112, Руководство пользователя

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MTD 112 9 06/97
3.1 APPLICATIONS
a) FLOOR MONITOR APPLICATIONS
The MTD 112 system is a full range two way passive system which is to be operated only
with the dedicated MTD 112 LLCa controller, connected in loop with one channel of a power
amplifier.
The specific disymmetrical wedge-shape of the MTD 112 allows its use as a floor-monitor.
Further, its conical and axisymmetric coverage provides a unique coherent sound field off
axis, devoid of the typical acoustic cancellation occurring when two physically separated
transducers are radiating the same frequency.
Explanation:
When the L.F. driver and H.F. driver are physically separated, like in most designs, this off-
axis acoustic cancellation occurs when the distances between each single driver and the
receiver differs by 1/2 wavelength.
This defines a preferred listening plane, normal to a line joining the acoustic centers of the
two drivers. In this case, the loudspeaker is to be used in one direction only, and cannot be
turned by 90° (unless a cancellation is accepted!).
The coaxial axisymmetric arrangement of the drivers in the MTD 112 gives no variation in
directivity whatever the plane of observation. The MTD 112 can be used in any position
without loss of performances, and this is obviously the best situation for floor-monitoring
applications.
When more than one MTD 112 is used as floor monitor dedicated to one performer, we do
not recommend pointing convergingly towards the performer. This typical triangular setup is
inspired from the stereo Hi-Fi, and is irrelevant with monitoring applications.
Note that in most cases, the signal fed into the pair of monitors is not stereo, but is simply
the same! A triangular setup results in a loss of coherence, the wavefronts from the two
sources interfering with each other.
We recommend instead the linear positioning of the monitors, all aiming towards parallel
directions. This setup has been proved highly satisfying when large SPL and wide coverage
were desirable on stage.
No subwoofer is to be used in this type of application.
b) FRONT OF HOUSE SOUND REINFORCEMENT
For Front Of House applications, the MTD 112 can be used with or without a subwoofer of
the L-ACOUSTICS range.
It is to be used in sound reinforcement applications as an individual sound source or
coupled in an array of two enclosures.
The ideal setup is when multiple sound sources are used with a time correction provided by
delay lines for compensating the time shifts due to their respective positions.
Due to its coaxial axisymmetric arrangement, the MTD 112 behaves acoustically like a true
point-source with directivity.
3. APPLICATIONS, CONFIGURATIONS & DIAGRAMS