L-Acoustics MTD Series, Руководство оператора

Страница: 26 / 69

L-ACOUSTICS MTD Manual V1.2 11/30/2004
25
OVER mode, a 100 Hz high pass filter is applied 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.
Note: The SB118 setting should be employed when using the LLC 112b-st controller for dV-SUB processing
(bandpass filtering and equalization are compatible)
In terms of connection, two input signals (Ch A, B) are applied to the line input XLR connectors on
the front panel of the LLC 112b-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 32 dB gain. The front panel of the LLC 112b-st is then
used as a patch panel with Ch A, B loudspeakers connected via the two 4-pin Speakon connectors
provided.
3.3 L-ACOUSTICS LLC 115b-st, LLC115b-2w DESCRIPTION
The L-ACOUSTICS LLC 115b-st or LLC 115b-2w line level controllers are analog signal processing
units that optimize the performance of the MTD115b loudspeaker when used in passive or active
mode, respectively. For stereo operation of passive MTD115b enclosures, the LLC 115b-st accepts
two signal inputs and provides two processed outputs for the respective input channels plus a filtered,
summed output for subwoofer drive. The LLC 115b-2w is for mono operation of active MTD115b
enclosures and accepts a single signal input while providing processed outputs for the subwoofer, low
and high frequency channels. The main functions of the LLC 115b-st and LLC 115b-2w controllers are
as follows:
• Bandpass filtering and equalization (3 modes, selectable)
• Crossover filtering for low and high channels (LLC 115b-2w only)
• Mono summation for subwoofer drive (LLC 115b-st only)
• 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 MTD115b
to suit different applications (selected via front panel switch). In MONITOR mode, high pass filtering is
set at 45 Hz and a modest low frequency shelf is applied to provide an equalization contour suitable
for floor monitor applications. In FRONT mode, a 45 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 since the MTD115b 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.
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 LLC 115b-st, two input signals (Ch A, B) are applied to the line input XLR connectors on the
front panel of the controller. Rear panel XLR line outputs (Ch A, B) are connected to the power