L-Acoustics MTD Series, Operator'S Manual

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L-ACOUSTICS MTD Manual V1.2 11/30/2004
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1.5 MTD115b SPECIFICATIONS
The MTD115b is a switch-selectable active/passive, two-way, coaxial full range loudspeaker containing
one direct radiating, bass reflex-loaded 15 inch low frequency transducer and one 1.4 inch exit, 3 inch
voice coil diameter, titanium alloy diaphragm compression driver. As a full range system, the
frequency response is 65 Hz to 14 kHz with less than ± 3 dB variation and the usable bandwidth is 50
Hz to 16 kHz (-10 dB).
The cone body of the low frequency driver provides pattern control loading of the compression
driver, yielding an 85-degree (± 20-degree) conical dispersion pattern that is axi-symmetrical. The 2
nd
and 3
rd
order passive filters employed in the MTD115b provide a 1.2 kHz crossover point between
low and high frequency components. In passive mode, long term power handling is 265 Wrms at a
nominal 8 ohm impedance. In active mode, the crossover point between low and high frequency
components is 1.2 kHz with 24 dB per octave Linkwitz-Riley characteristics and long term power
handling is 265 Wrms for the low section and 150 Wrms for the high section at a nominal 8 ohm
impedance. Connection to the loudspeaker is made via two parallel 4-pin Neutrik Speakon
connectors.
The MTD115b has a truncated wedge shape with a curved front profile. When used on its rear side,
the front baffle of the MTD115b is oriented at a 41 degree angle with respect to vertical, allowing the
enclosure to be used as a floor monitor.
Dimensions are 58 cm (22.8 in) high, 44 cm (17.3 in) wide at the front of the enclosure, 16.7 cm (6.6
in) wide at the rear and 47.5 cm (18.7 in) deep. Enclosure weight is 32.5 kg (71.6 lbs) and cabinet
construction consists of 18 mm (0.70 in) and 30 mm (1.18 in) Baltic birch plywood with internal steel
bracing and joints that are sealed, screwed and rabbeted. The finish is maroon-gray high resilient paint
and the front of the enclosure is protected by a black powder-coated, 1.5 mm (0.06 in) thick steel grill
that is covered with 10 mm (0.39 in) thick acoustically transparent open cell foam.
The MTD115b has a 36 mm (1.42 in) diameter pole mount socket mounted on the bottom side and a
single stud anchor plate mounted on the rear side along with four threaded inserts for attachment of
an optional Omnimount bracket. Four recessed attachment locations are provided (two on each top
and bottom side) for rigging the enclosure with the optional ETR2 adjustable U-bracket accessory.
When operated in passive mode, the MTD115b is used with the LLC115b-st stereo analog controller,
and in active mode, the LLC115b-2w mono two-way analog controller is specified. Both analog
controllers monitor power amplifier outputs and employ sense return processing to provide thermal
protection and cone excursion limiting for the loudspeaker components. Analog controllers also
provide band limiting and corrective component equalization with three settings that are designed for
front-of-house, floor monitor or two-way operation with subwoofers. The LLC115b-st stereo
controller performs signal summation of the two input signal channels and both controllers provide a
line level output signal with selectable band limiting and equalization for use of the MTD115b in
conjunction with SB115, SB118 or SB218 subwoofers.
Figure 5: MTD115b active/passive 2-way (15” LF + 1.4” HF) coaxial loudspeaker