Front-Of-House (Foh) Applications - L-Acoustics MTD Series Operator's Manual

possible in order to reduce the increase in SPL over the first few rows relative to the audience further
back in the coverage region.
OFFSTAGE FILL
When the horizontal coverage of the main left/right FOH arrays is not sufficient to cover the entire
audience area, MTD enclosures can also be used for offstage fill. Typically, throw distance
requirements are shorter and vertical coverage angles are greater, making MTD a possible solution for
this application.
Some Final Notes Concerning Fill Applications
LLC equalization and processing for MTD108a, MTD112b and MTD115b loudspeaker enclosures have been
specifically engineered to be sonically compatible with all other L-ACOUSTICS models. LLC controllers can
be set in either MONITOR or X-OVER modes for proximity fill applications where the audience is located
close to the fill loudspeaker system – for example, front fill or stereo infill configurations. For proximity fill
applications, the additional low frequency shelving equalization obtained using the FRONT setting is
probably not necessary (or desirable).
Time alignment of complementary fill systems with the main left/right FOH arrays is necessary in order to
achieve optimum results. Placing your measurement microphone in a representative location where the fill
and main system coverage overlaps generally provides a good reference point for time alignment. WINMLS,
SMAART or SPECTRAFOO are cost-effective measurement tools that are recommended for this purpose.

5.6 FRONT-OF-HOUSE (FOH) APPLICATIONS

When MTD018a, MTD112b or MTD115b enclosures are used standalone (without subwoofers) for
FOH applications, there are three different types of LLC processing available: 1) FRONT mode has
approximately 3 dB of low frequency shelving equalization in order to provide a frequency response
contour that is suitable for music applications; 2) MONITOR mode has a reduced amount of low
frequency shelving equalization and 3) X-OVER mode has a 100 Hz high pass filter and no low
frequency shelving equalization. Either MONITOR or X-OVER modes can be useful for speech
reinforcement and classical music applications, or for when MTD enclosures are used as a close
proximity fill enclosure
For 3-way operation of MTD112b or MTD115b loudspeaker enclosures with SB115, SB118, or SB218
subwoofers LLC processors should be set in X-OVER mode and the appropriate subwoofer model
selected via the front panel switches.
Note: The SB118 setting should be employed when using the LLC 115b-st or LLC 115b-2w controller for dV-
SUB processing (bandpass filtering and equalization are compatible)
For the MTD108LLCa analog controller, the subwoofer model is selected by changing a jumper on
the circuit board inside the unit. To configure the MTD108LLCa for other subwoofers:
1. Unplug the mains cable
2. Remove the cover of the controller (#8 philips screws for the top panel and #9 for the front
panel)
3. Locate the following text: SB115, MTD118, SB218, and SBX (front right side of the circuit board)
4. Place the jumper in the location corresponding to the desired subwoofer.
For all FOH applications, please refer to Sections 5.2, 5.3, 5.4 concerning MTD aiming, arraying and
coverage prediction. For additional information on using MTD enclosures with subwoofers, please
refer to Section 5.8.
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L-ACOUSTICS MTD Manual V1.2 11/30/2004