The L-ACOUSTICS® MTD112b loudspeaker enclosure and its accompanying analog controller provide a
highly versatile system that is designed
for distributed sound reinforcement.
Intended for medium-scale touring,
sub-hire or fixed installation, the
MTD112b features proven components that are compatible with
previous generation MTD enclosures
while also benefiting from the economy, packaging and "plug and play" ease
of use afforded by it's companion
LLC112b-st stereo line level analog
The MTD112b is a passive 2-way
loudspeaker enclosure containing a
1.4" exit compression driver that is
directly loaded by the 12"
loudspeaker in a coaxial configuration.
Advantages of the coaxial approach
include: single point source radiation
and excellent phase response, total
wavefront coherency at all frequencies
and axi-symmetrical directivity that
produces identical horizontal and
vertical coverage. Coaxial design also
provides LF/HF superimposed dispersion characteristics that are free of
polar lobing effects typical of traditional horn and woofer combinations.
The end result is natural, studio
monitor level sound quality, ideal for
proximity use and perfectly matching
semi-reverberant environments.
The MTD112b is designed for distributed sound reinforcement and can
also be used in medium power frontof-house (FOH) applications for
theatres, clubs, multi-purpose venues
or corporate events. Examples of
distributed systems include delay rings
for large-scale installations, surround
effects channels for theatre or multimedia, distributed reinforcement for
sports venues and delays for speech
reinforcement in convention centre
ballrooms. Due to its compact, wedgeshaped format, axi-symmetrical
directivity and full range passive design,
the MTD112b also provides a
cost-effective floor monitor solution
for live sound reinforcement. When
used with additional subwoofers such
as the SB115, SB118 or SB218, the
MTD112b can be used in side fill or
drum monitoring applications.
The L-ACOUSTICS LLC112b-st is a
dedicated stereo analog controller that
provides optimum processing and
sense return protection for the
MTD112b. Front panel design of the
LLC112b-st allows the unit to function
as a patch panel, providing an ergonomic, cost-effective solution for
amplifier rack packaging.
A pole mount socket and single stud
anchor plate are included as standard
on the MTD112b and the enclosure is
Omnimount-ready. An adjustable
U-bracket is available as an optional
rigging accessory for ceiling, wall or
scaffold mounting.
Passive two-way enclosure
(12" LF, 1.4" HF)
High power coaxial
driver assembly
Point source radiation
(85° conical directivity)
Flexible format for
distributed sound
Wedge-shaped for floor
monitor use
Suitable for mediumpower FOH applications
Designed for both fixed
installation and touring
Compact, rugged
flexible rigging
Analog processor
control with sense
return protection
L-ACOUSTICS specifications are based on measurement procedures which produce unbiased results and allow for realistic performance prediction and simulation.
Some of these specifications will appear very conservative when compared with other manufacturer ’s specifications. All measurements are conducted under free
field conditions and scaled to a 1 m reference distance unless otherwise indicated.
Frequency Response
Frequency response
70 - 14k Hz (±3 dB)
Usable bandwidth
55 - 16k Hz (-10 dB)
(2.83 Vrms @ 1m)
98 dB SPL
(LLC FRONT position)
70 - 14k Hz
540 mm
21.3 in
•Front Width
410 mm
16.1 in
•Rear Width
165 mm
6.5 in
375 mm
14.8 in
45 degrees with
respect to vertical
•Trap Angle
500 W
8 ohms
•Net Weight
27.5 kg
60.6 lbs
•Shipping Weight
30.5 kg
67.2 lbs
*Amplifiers must have 32 dB gain in order for LLC112b-st sense return protection to function properly
•Shipping Dims
615 x 470 x 465 mm
Nominal Directivity (-6dB)3
85° (± 20°)
•Connectors : 2x 4-pin Neutrik speakon
Power Rating2
(Long Term)
45 Vrms
250 Wrms
System Output4
One enclosure
1000 Wpeak
24.2 x 18.5 x 18.3 in
•Material : 18 mm, 30 mm Baltic birch plywood
120.5 dB (cont)
122.5 dB (cont)
126.5 dB (peak)
128.5 dB (peak)
FRONT mode
X-OVER mode
FRONT LLC setting provides a 3 dB low frequency contour under freefield conditions
•Finish : Maroon-gray™
•Grill : Black epoxy perforated steel with
acoustically transparent foam
•Rigging : Integrated flying hardware,
X-OVER LLC setting applies a 100 Hz high pass filter
LF 1 x 12'' weather resistant loudspeaker (4'' voice coil)
HF 1 x 1.4'' exit compression driver (titanium diaphragm, 3" voice coil, coaxial assembly)
Additional Equipment
•L-ACOUSTICS LLC112b-st analog controller
•L-ACOUSTICS SB115, SB118, SB218
Sensitivity is the average SPL measured over the component’s rated bandwidth
Power rating displays the long term RMS power handling
capacity using pink noise with a 6 dB crest factor over the
component’s rated bandwidth
L-ACOUSTICS ® is a registered trademark
Directivity is averaged over the 1-10 kHz range
System Output gives the unweighted SPL output of the system referenced to 1 m, including preset equalization and band
leveling adjustment as measured under freefield conditions.
•L-ACOUSTICS LA 15a, LA 17a or LA 24a
power amplifier
The enclosure shall be a passive, two-way, coaxial full range loudspeaker
containing one direct radiating, bass reflex-loaded 12 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
shall be 70 Hz to 14 kHz with less than ± 3 dB variation and the usable
bandwidth shall be 55 Hz to 16 kHz (-10 dB).
The cone body of the low frequency component shall provide pattern control
loading of the compression driver and yield an 85-degree conical dispersion
pattern that is axi-symmetrical. The 2nd and 3rd order passive filters
employed in the enclosure shall provide a 1.2 kHz crossover point between
low and high frequency components. Long term power handling shall be
250 Wrms at a nominal 8-ohm impedance. Connection to the loudspeaker shall
be made via two parallel 4-pin Neutrik Speakon connectors.
The enclosure shall have a truncated wedge shape with a curved front
profile. Dimensions shall be 54 cm (21.3 in) high, 41 cm (16.1 in) wide at the
front of the enclosure, 16.5 cm (6.5 in) wide at the rear of the enclosure and
37.5 cm (14.8 in) deep. When used on its rear side, the front baffle of the
enclosure shall be oriented at a 45-degree angle with respect to vertical,
allowing the enclosure to be used as a floor monitor. Enclosure weight shall
be 27.5 kg (60.6 lbs). Cabinet construction shall consist 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 shall be maroon-gray high
resilient paint. The front of the enclosure shall be protected by a black
powder-coated, 1.5 mm (0.06 in) thick steel grill that is covered with 10 mm
(0.4 in) thick acoustically transparent open cell foam.
The enclosure shall have 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 shall be provided
(2 each on the top and bottom sides) for rigging the enclosure with an
adjustable U-bracket accessory with angular adjustment in steps of
10 degrees.
The enclosure shall be used with a stereo analog controller that monitors
power amplifier outputs and employs sense return processing to provide
thermal protection and cone excursion limiting for the loudspeaker components. The analog controller shall 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
analog controller shall perform signal summation of the two input signal
channels and provide a line level output signal with selectable band limiting
and equalization for use of the enclosure in conjunction with three different
subwoofer types.
The loudspeaker system shall be the L-ACOUSTICS MTD112b.
The analog loudspeaker controller shall be the L-ACOUSTICS LLC112b-st.
The subwoofer system shall be the L-ACOUSTICS SB115, SB118 or SB218.
U-Bracket for ceiling, wall or scaffold mounting of the
MTD112b with angular adjustment in steps of 10 degrees.
A bracket mount plate is first attached to the 4 mount
locations provided on the enclosure (2 each on the top and
bottom sides).The U-bracket is then attached to the mount
plate using two threaded knobs - one for attachment of the
bracket, one for tilt of the enclosure.
SCALE 1:15
PION1: Single stud Aeroquip flytrack fitting to ring.
(Dimensions in mm)
On-axis frequency response (LLC112b-st FRONT position)
Frequency response averaged over -3dB beamwidth
The L-ACOUSTICS LLC112b-st stereo line level controller is an
analog signal processing unit that optimizes the performance of the MTD112b.
The controller accepts two signal inputs and provides two processed outputs
for the respective input channels plus a filtered, summed output for
subwoofer drive. The main functions of the LLC112b-st controller are as
• Bandpass filtering and equalization (3 modes, selectable)
• Mono input summation for subwoofer drive
• Crossover filtering, equalization for subwoofer drive
(3 models, switch-selectable)
• Sense Return processing for thermal protection of speaker components and
cone excursion limiting (voltage and frequency dependent)
Three different equalization/bandpass filtering modes tailor the frequency
response of the MTD112b to suit different applications (selected via front panel
switch). In MONITOR mode, high pass filtering is set at 50 Hz and a modest
low frequency shelf is applied to provide an equalization contour suitable for
floor monitor applications. In FRONT mode, a 50 Hz high pass filter is
employed and increased low frequency shelving provides an equalization
contour that is more suitable for FOH use. In X-OVER mode, a 100 Hz high
pass filter is applied and there is no low frequency shelving equalization since
the MTD112b is intended to be used with additional subwoofers.
For subwoofer drive, the second front panel switch allows for selection of
bandpass filtering and equalization that is optimized for either SB115, SB118 or
SB218 subwoofers. The processed subwoofer signal output is then available on
the XLR connectors provided on the front or rear panels of the controller.
In terms of connection, two input signals (Ch A, B) are applied to the line input
XLR connectors on the front panel of the LLC112b-st. Rear panel XLR line
outputs (Ch A, B) are connected to the power amplifier inputs with the
amplifier outputs then connected to the controller "Sense Return" input
Speakon connector (Ch A = 1+/1-, Ch B = 2+/2-). Since the amplifier is
connected in a loop, LLC sense return protection circuitry can monitor the
signal applied to the loudspeakers and provide thermal protection of speaker
components plus voltage- and frequency-dependent cone excursion limiting
provided that the power amplifier has a gain of 32 dB. The front panel of the
LLC112b-st is then used as a patch panel with Ch A, B loudspeakers connected
via the two 4-pin Speakon connectors provided.
Electronically balanced 10 kΩ input (pin 2 hot)
Electronically balanced 50 Ω output (pin 2 hot)
Input Headroom
+20 dBV
Nominal Gain at 200 Hz
0 dB (unity gain) in X-OVER mode
Signal to Noise
> 84 dB
Dynamic Range
> 104 dB
<0.01% (20 to 20k Hz @ 0 dBV)
Bandpass/Equalization Filters
3 modes
FRONT: 50 Hz LR24 HPF + low frequency shelving eq
X-OVER: 100 Hz LR24 HPF
Speaker Protection
20 kHz
25, 26, 40 Hz LR24 HPF (for SB218, SB118, SB115)
100 Hz LR24 LPF
RMS limiter & peak limiter
Front & Rear Panel
Signal: green LED for each channel
Control: yellow LED for each channel
Front Panel Controls
SUB select (SB115, SB118, SB218)
AC power switch
Rear Panel Control
SUB POLARITY (positive, negative)
Front Panel Connectors
Ch A, B XLR inputs with parallel loop through
MONO SUB XLR output (in parallel with rear panel XLR)
LOUDSPEAKERS OUT Ch A, B: 2 x 4-pin Neutrik speakon
(Ch A=1+/1- & Ch B=1+/1-)
Rear Panel Connectors
Ch A, B XLR line outputs
MONO SUB XLR output (in parallel with front panel XLR)
Sense Return: 1x 4-pin Neutrik speakon
(Ch A=1+/1-, Ch B=2+/2-)
Power Requirement
Power Consumption
100 V - 240 V 50/60 Hz
15 W
Black anodized front panel, white serigraphy
Net Dimensions
483 x 44 x 305 mm
19 x 1.75 x 12.0 in
Net Weight
3.75 kg
Shipping :
8.3 lbs
4.8 kg 10.6 lbs
505 x 80 x 415 mm
19.9 x 3.1 x 16.3 in
Specifications subject to change without notice
Specs MTD112b 0103
w w w. l - a c o u s t i c s . c o m
Parc de la Fontaine de Jouvence • 91462 Marcoussis Cedex • France • Ph:+33 (0) 1 69 63 69 63 • Fax: +33 (0) 1 69 63 69 64 •