L-Acoustics MTD Series Operator's Manual
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L-Acoustics MTD Series Operator's Manual

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Version 1.2
December 2004
L-ACOUSTICS MTD LINE
MTD108a, MTD112b, MTD115b
OPERATOR MANUAL

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  • Page 1 Version 1.2 December 2004 L-ACOUSTICS MTD LINE MTD108a, MTD112b, MTD115b OPERATOR MANUAL...

  • Page 2: Foreword

    Specific information and recommendations are included regarding system design, sound design and installation. We are confident that the information provided in this manual will be sufficient for most ® applications, however, should you require further assistance your distributor or L-ACOUSTICS available to provide additional technical support. MANUAL ORGANIZATION The Introduction gives a brief presentation of coaxial technology and the MTD line.
  • Page 3 L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 4: Table Of Contents

    2.4 POWERING MTD115b (ACTIVE MODE)....................20 2.5 CONNECTORS AND CABLES ........................23 3. PROCESSING MTD..........................24 3.1 L-ACOUSTICS MTD108 LLCa DESCRIPTION ....................24 3.2 L-ACOUSTICS LLC 112b-st DESCRIPTION ....................24 3.3 L-ACOUSTICS LLC 115b-st, LLC115b-2w DESCRIPTION................25 4. MTD CONFIGURATIONS .........................26 4.1 MTD108a FLOOR MONITOR SYSTEM .......................

  • Page 5: List Of Figures

    Figure 4: MTD112b passive 2-way (12” LF + 1.4” HF) coaxial loudspeaker ........14 Figure 5: MTD115b active/passive 2-way (15” LF + 1.4” HF) coaxial loudspeaker......15 Figure 6: MLS switches on the rear panel of L-ACOUSTICS LA24a, LA48a amplifiers......16 Figure 7a: MTD108a Floor Monitor System Block Diagram ..............27 Figure 7b: MTD108a Floor Monitor System Cabling Detail..............27...

  • Page 6: List Of Tables

    Table 12: Recommended power amplification and MLS switch settings for MTD115b high section ..21 Table 13: Recommended MLS switch settings for powering MTD115b (active mode) ......21 Table 14: Output Power Ratings and MLS Switch Settings for L-ACOUSTICS LAa Amplifiers ....22 Table 15: Maximum Recommended Length for Damping Factor > 20..........23 Table 16: Nominal floor monitor distance (to performer) and separation versus performer height ..47...

  • Page 7: Introduction

    British manufacturer for studio monitoring applications – to the best of our knowledge, L-ACOUSTICS was the first manufacturer to use coaxial technology in professional sound reinforcement applications and the current MTD line is a continuation of the heritage that was introduced in 1989.

  • Page 8: The Mtd System

    Extensive sound design and installation experience acquired by L-ACOUSTICS over the years confirms this and we are confident that coaxial, axi-symmetric loudspeaker enclosures are the best tools for multiple source, distributed sound design.
  • Page 9 2 x Speakon connectors (13) F-LINK CABLE (SP.7) Loudspeaker link cable, 4 conductor, 4mm conductor cross-section, 0.7 m (2 ft) length, equipped with 2 x Speakon connectors (for paralleling MTD enclosures). ETR8 MTD108a L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 10: Figure 1: Mtd System Components

    MTD112b ETR1 MTD115b ETR2 (for MTD115b or SB115) PION1 F-LINK CABLE DO.7 F-CABLE DO7 Figure 1: MTD System Components L-ACOUSTICS MTD Manual V1.2 11/30/2004...
  • Page 11 MTD108 LLCa (front) MTD108 LLCa (rear) LLC112b-st (front) LLC112b-st (rear) L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 12: Figure 2: Mtd Llc Controllers

    LLC115b-st (front) LLC115b-st (rear) LLC115b-2w (front) LLC115b-2w (rear) Figure 2: MTD LLC Controllers L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 13: Mtd Overview

    1.2 MTD OVERVIEW L-ACOUSTICS MTD108a, MTD112b and MTD115b loudspeaker enclosures along with their respective analog controllers provide highly versatile, multi-purpose systems that are designed for distributed sound reinforcement. Intended for medium-scale touring, sub-hire or fixed installation, the MTD line of enclosures benefit from the economy, packaging and “plug and play” ease of use afforded by their companion LLC analog line level controllers.

  • Page 14: Mtd108A Specifications

    MTD108a using the optional ETR8 adjustable U bracket. The L-ACOUSTICS MTD108LLCa is a stereo analog controller that provides optimum equalization and band limiting for the MTD108a along with system protection and processing for use with subwoofers.

  • Page 15: Mtd112B Specifications

    MTD112b in conjunction with SB115, SB118 or SB218 subwoofers. Figure 4: MTD112b passive 2-way (12” LF + 1.4” HF) coaxial loudspeaker L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 16: Mtd115B Specifications

    MTD115b in conjunction with SB115, SB118 or SB218 subwoofers. Figure 5: MTD115b active/passive 2-way (15” LF + 1.4” HF) coaxial loudspeaker L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 17: Powering Mtd

    MTD108a, MTD112b or MTD115b (active or passive mode) enclosures. As standard, L-ACOUSTICS LA power amplifiers are 32 dB gain and there are four models available: LA15a, LA17a, LA24a and LA48a (please see Table 11 for a specification summary). L-ACOUSTICS LA amplifiers can be configured to provide power matching into different loads (for example, Figure 6 shows the location of MLS switches on the LA24a and LA48a rear panel).

  • Page 18: Powering Mtd108A

    (-2 dB) (-4 dB) L-ACOUSTICS LA amplifier MLS switch settings for powering the MTD108a are summarized in Table 4 and Figure 6 shows the location of MLS switches on the LA24a and LA48a rear panel. Table 3: Recommended MLS switch settings for powering MTD108a...

  • Page 19: Powering Mtd112B

    (-2 dB) (-4 dB) L-ACOUSTICS LA amplifier MLS switch settings for powering the MTD112b are summarized in Table 6 and Figure 6 shows the location of MLS switches on the LA24a and LA48a rear panel. Table 6: Recommended MLS switch settings for powering MTD112b...

  • Page 20: Powering Mtd115B (Passive Mode)

    (0 dB) (-2 dB) (-4 dB) L-ACOUSTICS LA amplifier MLS switch settings for powering the MTD115b in passive mode are summarized in Table 9 and Figure 6 shows the location of MLS switches on the LA24a and LA48a rear panel.

  • Page 21: Powering Mtd115B (Active Mode)

    440 1760 1760 600 2400 2400 HIGH Based on these specifications, recommended L-ACOUSTICS LA power amplifier specifications and MLS switch settings are summarized below in Tables 11 and 12. Table 11: Recommended power amplification and MLS switch settings for MTD115b low section...

  • Page 22: Table 12: Recommended Power Amplification And Mls Switch Settings For Mtd115B High Section

    Table 13: Recommended MLS switch settings for powering MTD115b (active mode) MTD115b (ACTIVE) MLS SETTING LA15a LA17a LA24a LA48a MTD115b LO SECTION 0 dB 0 dB -2 dB -4 dB MTD115b HI SECTION 0 dB 0 dB -2 dB -4 dB L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 23: Table 14: Output Power Ratings And Mls Switch Settings For L-Acoustics Laa Amplifiers

    1380 1665 2130 2700 2 ohms Stereo (2 channel) 1200 1400 1550 1700 2 ohms Stereo (2 channel) 1660 2000 2400 2900 Table 14: Output Power Ratings and MLS Switch Settings for L-ACOUSTICS LAa Amplifiers L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 24: Connectors And Cables

    360 ft 60 m 180 ft As standard, L-ACOUSTICS F-CABLE (SP7, SP25) and F-LINK CABLE (SP.7) loudspeaker cables are 4 conductor cables with 4 mm conductor cross-section (11 gauge). SP25 cables can be used for 25 meter cable runs to power a 4 ohm load (2 x MTD108a, MTD112b or MTD115b enclosures in parallel) while maintaining a damping factor greater than 20.

  • Page 25: Processing Mtd

    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.

  • Page 26: L-Acoustics Llc 115B-St, Llc115B-2W Description

    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.

  • Page 27: Mtd Configurations

    Please refer to sections 4.1 - 4.3 for MTD108a examples, sections 4.4 - 4.6 for MTD112b examples, sections 4.7 – 4.9 for MTD115b (passive) examples and sections 4.10 – 4.12 for MTD115b (active) examples. L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 28: Mtd108A Floor Monitor System

    4.1 MTD108a FLOOR MONITOR SYSTEM Figure 7b: MTD108a Floor Monitor System Cabling Detail Figure 7a: MTD108a Floor Monitor System Block Diagram L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 29: Mtd108A Foh System (Mono Subs)

    4.2 MTD108a FOH SYSTEM (MONO SUBS) Figure 8b: MTD108a FOH System Cabling Detail (mono subwoofers) Figure 8a: MTD108a FOH System Block Diagram (mono subwoofers) L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 30: Mtd108A Foh System (Stereo Subs)

    4.3 MTD108a FOH SYSTEM (STEREO SUBS) Figure 9a: MTD108a FOH System Block Diagram (stereo subwoofers) (note: LLC ChA to ChB link provides +6 dB increase for subwoofer drive) Figure 9b: MTD108a FOH System Cabling Detail (stereo subwoofers) L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 31: Mtd112B Floor Monitor System

    4.4 MTD112b FLOOR MONITOR SYSTEM Figure 10b: MTD112b Floor Monitor System Cabling Detail Figure 10a: MTD112b Floor Monitor System Block Diagram L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 32: Mtd112B Foh System (Mono Sub)

    4.5 MTD112b FOH SYSTEM (MONO SUB) Figure 11a: MTD112b FOH System Block Diagram (mono subwoofers) Figure 11b: MTD112b FOH System Cabling Detail (mono subs) L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 33: Mtd112B Foh System (Stereo Subs)

    4.6 MTD112b FOH SYSTEM (STEREO SUBS) Figure 12a: MTD112b FOH System Block Diagram (stereo subwoofers) Figure 12b: MTD112b FOH System Cabling Detail (stereo subwoofers) (note: LLC ChA to ChB link provides +6 dB increase for subwoofer drive) L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 34: Mtd115B (Passive) Floor Monitor System

    4.7 MTD115b (PASSIVE) FLOOR MONITOR SYSTEM Figure 13a: MTD115b (passive) Floor Monitor System Block Diagram Figure 13b: MTD115b (passive) Floor Monitor System Cabling Detail L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 35: Mtd115B (Passive) Foh System (Mono Sub)

    4.8 MTD115b (PASSIVE) FOH SYSTEM (MONO SUB) Figure 14b: MTD115b (passive) FOH System Cabling Detail (mono subs) Figure 14a: MTD115b (passive) FOH System Block Diagram (mono subs) L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 36: Mtd115B (Passive) Foh System (Stereo Subs)

    4.9 MTD115b (PASSIVE) FOH SYSTEM (STEREO SUBS) Figure 15a: MTD115b (passive) FOH System Block Diagram (stereo subs) Figure 15b: MTD115b (passive) FOH System Cabling Detail (stereo subs) (note: LLC ChA to ChB link provides +6 dB increase for subwoofer drive) L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 37: Mtd115B (Active) Floor Monitor System

    4.10 MTD115b (ACTIVE) FLOOR MONITOR SYSTEM Figure 16a: MTD115b (active) Floor Monitor System Block Diagram Figure 16b: MTD115b (active) Floor Monitor System Cabling Detail L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 38: Mtd115B (Active) Foh System (Stereo Sb118 Subs)

    4.11 MTD115b (ACTIVE) FOH SYSTEM (STEREO SB118 SUBS) Figure 17a: MTD115b (active) FOH System Block Diagram (stereo SB118) Figure 17b: MTD115b (active) FOH System Cabling Detail (stereo SB118) L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 39: Mtd115B (Active) Foh System (Stereo Sb218 Subs)

    4.12 MTD115b (ACTIVE) FOH SYSTEM (STEREO SB218 SUBS) Figure 18b: MTD115b (active) FOH System Cabling Detail (stereo SB218) Figure 18a: MTD115b (active) FOH System Block Diagram (stereo SB218) L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 40: Sound Design

    Due to their compact, wedge-shaped format and axi-symmetrical directivity, MTD108a, MTD112b or MTD115b enclosures also provide an exceptionally high performance floor monitor solution. When used in conjunction with L-ACOUSTICS SB115, SB118 or SB218 subwoofers, MTD enclosures are also suitable for side fill and drum monitoring applications.

  • Page 41: Arraying Mtd Enclosures

    CATT-Acoustic modeling software), demonstrating the evenness of coverage and single point source behavior that is obtained using coaxial technology. Note: For color versions of figures 20, 21, 22 and 24 please see the MTD manual PDF file that is available for download from www.l-acoustics.com 250 Hz 125 Hz...

  • Page 42: Figure 21: Spl Mappings For Two Mtd Enclosures With 0.5 Metre Spacing

    500 Hz 1 kHz 2 kHz 4 kHz Figure 22: SPL mappings at octave band frequencies for two MTD enclosures with 3 metre spacing (distributed system corresponding to the “best” case shown in Figure 23) L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 43: Figure 23: General Guidelines For Arraying Mtd Enclosures

    500 Hz 1 kHz 2 kHz 4 kHz Figure 24: SPL mappings at octave band frequencies for four MTD enclosures with 0.5 metre spacing (arrayed system corresponding to the “avoid” case shown in Figure 23). L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 44: Predicting Mtd Coverage

    Center-to-center overlap based on the -6 dB coverage angles will provide the most uniform coverage (see also 4.5.1). Time domain-based measurement equipment is highly useful for setting delay times (for example, MLSSA, WINMLS, TEF, SMAART or SPECTRAFOO). Alternatively, Bushnell Yardage Pro rangefinder L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 45: Complementary Fill

    Special attention should be paid to the first few rows and typically, a stacked height of at least 1-2 meters is recommended. If possible, use distance-attenuation loss to your advantage and try to move MTD enclosures as far upstage as L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 46: Front-Of-House (Foh) 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 –...

  • Page 47: Stage Monitoring

    Ultimately, it all comes down to artist preference and what you’re shooting for in a monitor mix but if you want optimum coverage and nominally flat, follow the spacing/distance recommendations given in Table 16 and don’t angle the wedges in. L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 48: Table 16: Nominal Floor Monitor Distance (To Performer) And Separation Versus Performer Height

    5 ft 11 in 5 ft 2 in 4 ft 8 in 6 ft 1 in 5 ft 3 in 4 ft 10 in 6 ft 3 in 5 ft 5 in 4 ft 12 in L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 49: Using Mtd With Subwoofers

    5.8 USING MTD WITH SUBWOOFERS For extended bandwidth sound reinforcement, MTD108a, MTD112b or MTD115b enclosures should be used with SB115, SB118, SB218 or dV-SUB subwoofers. As a quick reference, L-ACOUSTICS subwoofer specifications are summarized in Table 17 and Fig 25.

  • Page 50: Combining Mtd With Subwoofers

    MTD system versus ground stacked subwoofers. Typically, LLC controllers are used in X-OVER mode for ground stacked configurations in order to optimize power bandwidth for the subwoofer and the MTD low frequency component. L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 51: Separate Flown Mtd With Ground Stacked Subwoofers

    (FLOWN SYSTEM) PATH PATH DIFFERENCE DIFFERENCE FLOWN= sub (m) MEASUREMENT STAGE MICROPHONE (SB218) (SB218) sub (m) FLOOR TIME DELAY PATH DIFFRENCE (meters) 343 (meters/second) Figure 26: Illustration of subwoofer time alignment L-ACOUSTICS MTD Manual V1.2 11/30/2004...

  • Page 52: Installation Procedures

    (8) Always install with the fixed arm on the bottom when (7) Three attachment points are available for ceiling installing the MTD108a in the vertical orientation or scaffold mounting in the horizontal orientation Figure 27: ETR8 U-bracket installation procedure L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 53: Etr1, Etr2 U-Bracket Attachment (Mtd112B, Mtd115B)

    (9) The smaller knob allows for tilt angle adjustment (10) Three attachment points available for ceiling or scaffold mounting in the horizontal orientation only. Single stud plate available for safety attachment using PION1 Figure 28: ETR1, ETR2 U-bracket installation procedure L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 54: Omnimount Bracket Attachment (Mtd112B, Mtd115B)

    ETR1 and ETR2 are for installation of MTD112b or MTD115b enclosures, respectively, in the horizontal orientation only. L-ACOUSTICS recommends the use of safety steels at all times. The integrated single stud anchor plate and the PION1 single stud fitting can be used for safety attachment for MTD112b and MTD115b enclosures.

  • Page 55: Mtd System Operation

    (for example: 13 volts from 1 kHz to 18 kHz). Re-mount the entire MTD coaxial assembly in its enclosure and perform a system polarity check. Following service, the damaged compression driver diaphragm should be returned to your distributor or directly to L-ACOUSTICS for warranty examination. L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 56: Spare Parts

    - there is no need to completely remove the acoustic foam in order to remove the loudspeaker grille. The damaged loudspeaker should be returned to your distributor or directly to L-ACOUSTICS for warranty examination and reconing.

  • Page 57: Specifications

    2x 4-pin Neutrik speakon Material 15 mm, 18 mm Baltic birch plywood (sealed, screwed and rabbeted angles) Finish Maroon-gray™ Grill Black epoxy perforated steel with acoustically transparent foam Rigging Integrated flying hardware and pole mount socket, Omnimount-ready L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 58: Figure 30: Mtd108A Line Drawing

    Figure 30: MTD108a line drawing L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 59: Figure 31: Mtd108A Plus Etr8 Line Drawings

    Figure 31: MTD108a plus ETR8 line drawings L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 60: Mtd108Llca Specifications

    483 x 44 x 305 mm 19 x 1.75 x 12.0 in Net Weight 3.75 kg 8.3 lbs Shipping Dimensions 505 x 80 x 415 mm 19.9 x 3.1 x 16.3 in Shipping Weight 4.8 kg 10.6 lbs L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 61: Mtd112B Specifications

    2x 4-pin Neutrik speakon Material 18 mm, 30 mm Baltic birch plywood (sealed, screwed and rabbeted angles) Finish Maroon-gray™ Grill Black epoxy perforated steel with acoustically transparent foam Rigging Integrated flying hardware, handles and pole mount socket, Omnimount-ready L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 62: Figure 32: Mtd112B Line Drawing

    Figure 32: MTD112b line drawing L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 63: Figure 33: Mtd112B Plus Etr1 Line Drawings

    Figure 33: MTD112b plus ETR1 line drawings L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 64: Llc112B-St Specifications

    483 x 44 x 305 mm 19 x 1.75 x 12.0 in Shipping Dimensions 505 x 80 x 415 mm 19.9 x 3.1 x 16.3 in Net Weight 3.75 kg 8.3 lbs Shipping Weight 4.8 kg 10.6 lbs L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 65: Mtd115B Specifications

    Material 18 mm, 30 mm Baltic birch plywood (sealed, screwed and rabbeted angles) Finish Maroon-gray™ Grill Black epoxy perforated steel with acoustically transparent foam Rigging Integrated flying hardware, handles and pole mount socket, ` Omnimount-ready L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 66: Figure 34: Mtd115B Line Drawing

    Figure 34: MTD115b line drawing L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 67: Figure 35: Mtd115B Plus Etr2 Line Drawings

    Figure 35: MTD115b plus ETR2 line drawings L-ACOUSTICS MTD Manual V1.2 30-11-04...

  • Page 68: Llc115B-St, Llc115B-2W Specifications

    MONO SUB XLR output (in parallel with rear panel XLR) LOUDSPEAKERS OUT Ch A, B: 2x4-pin Neutrik speakon LLC115b-2w Single XLR input with parallel loop through MONO SUB XLR output (in parallel with rear panel XLR) LOUDSPEAKER OUT : 1x4-pin Neutrik speakon L-ACOUSTICS MTD Manual V1.2 30-11-04...
  • Page 69 483 x 44 x 305 mm 19 x 1.75 x 12.0 in Shipping Dimensions 505 x 80 x 415 mm 19.9 x 3.1 x 16.3 in Net Weight 3.7 kg 8.2 lbs Shipping Weight 4.8 kg 10.6 lbs L-ACOUSTICS MTD Manual V1.2 30-11-04...

This manual is also suitable for:

Mtd108aMtd112bMtd115b

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