L-Acoustics MTD Series User Manual

L-ACOUSTICS MTD Manual V1.2 11/30/2004 24
3. PROCESSING MTD
3.1 L-ACOUSTICS MTD108 LLCa DESCRIPTION
The MTD108LLCa line level controller is an analog signal processing unit that optimizes the
performance of the MTD108a. The stereo controller accepts two signal inputs and provides two
processed outputs for the respective input channels. The main functions of the MTD108LLCa
controller are as follows:
• Bandpass filtering and equalization (3 modes, selectable)
• Sense Return processing for thermal protection of speaker components and cone excursion
limiting (voltage and frequency dependent)
• Mono input summation for subwoofer or center fill drive
• Crossover filtering, equalization for subwoofer drive
Three different equalization/bandpass filtering modes tailor the frequency response of the MTD108a
for different applications. In MONITOR mode, high pass filtering is set at 80 Hz with a 12 dB/octave
slope in order to provide an equalization contour suitable for speech reinforcement or floor monitor
applications. In FRONT mode, a 50 Hz high pass filter is employed and low frequency shelving
equalization provides a contour more suitable for full bandwidth music applications. In X-OVER mode,
a 125 Hz high pass filter is applied since the MTD108a is intended to be used with subwoofers.
When the second front panel switch is set to SUB mode, the mono output on the rear of the
controller provides a summed output of the two signal inputs with low pass filtering set at 125 Hz and
equalization optimized for the SB115 subwoofer (equalization for the MTD118 or SB218 are
selectable via internal jumpers). Alternatively, the summed MONO signal output can be used to feed a
power amplifier allotted to a central fullrange fill loudspeaker (SUM mode).
The MTD108LLCa is connected in series with two amplifier channels for sense return processing, i.e.,
amplifier outputs are connected to the "Sense Return" input of the MTD108LLCa. Protection circuitry
monitors the signal applied to the loudspeakers to provide thermal protection of speaker components
plus voltage and frequency dependent cone excursion limiting.
3.2 L-ACOUSTICS LLC 112b-ST DESCRIPTION
The L-ACOUSTICS LLC 112b-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 LLC 112b-st controller are as follows:
• 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-

L-Acoustics MTD Series Specifications

General

Brand	L-Acoustics
Model	MTD Series
Category	Speakers
Language	English