L-Acoustics V-DOSC Operator's Manual
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L-Acoustics V-DOSC Operator's Manual

L-Acoustics V-DOSC Operator's Manual

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Version 4
June 2005
V-DOSC
OPERATOR MANUAL

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Summary of Contents for L-Acoustics V-DOSC

  • Page 1 Version 4 June 2005  V-DOSC OPERATOR MANUAL...
  • Page 2 L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 2 of 158...
  • Page 3 FOREWORD This manual is intended for Qualified V-DOSC Technicians and Certified V-DOSC Engineers who are  responsible for the installation and operation of the V-DOSC sound reinforcement system. It is also intended to provide interested sound engineers, designers, consultants and installers with information ...
  • Page 4 R&D. In closing, it has been an honor and a pleasure to work with V-DOSC over the years and a few thank you’s are in order: ®...

  • Page 5: Table Of Contents

    V-DOSC: THE SOLUTION ......................14 V-DOSC TRAINING AND QUALIFICATIONS ..................18 QUALIFIED V-DOSC TECHNICIAN (QVT) ................18 CERTIFIED V-DOSC ENGINEER (CVE)..................18 1. THE V-DOSC SYSTEM STANDARD ....................19 1.1 V-DOSC SYSTEM COMPONENTS ....................23 LOUDSPEAKER ENCLOSURES ....................23 RIGGING ACCESSORIES......................24 SUBWOOFER ENCLOSURES.......................
  • Page 6 Flat V-DOSC Array........................64 Curved V-DOSC Array........................64 Constant Curvature V-DOSC Array..................... 65 Variable Curvature V-DOSC Array ....................66 2.3 V-DOSC COVERAGE MODELING USING ARRAY 2004............... 66 CUTVIEW SHEETS........................67 V-ARRAY1, V-ARRAY2 Input Data ....................67 Optimization Procedure........................ 69 Output Data........................... 70 dV-ARRAY1, dV-ARRAY2 Input Data..................
  • Page 7 APPENDIX 1: Why Do Separated Sound Sources Interfere?............142 APPENDIX 2: Further Explanations Regarding WST Criteria ............142 APPENDIX 3: How Does V-DOSC Behave With Respect To WST Criteria........148 APPENDIX 4: How Does the DOSC Waveguide Work? ..............149 APPENDIX 5: The Border Between Fresnel And Fraunhofer Regions ...........

  • Page 8: List Of Figures

    Figure 29: L-ACOUSTICS RK124a amplifier rack channel assignments and cabling........46 Figure 30: L-ACOUSTICS RK122a amp rack channel assignments for 2-way, 3-way stereo presets .... 47 Figure 31: L-ACOUSTICS RK124a amp rack channel assignments for 2-way, 3-way stereo presets .... 48 Figure 32: CO24 Control Output Panel......................
  • Page 9 Figure 65: LCR Configurations ........................89 Figure 66: Generic rigging plot for a V-DOSC system with main L/R FOH and LL/RR offstage fill arrays..90 Figure 67: Rigging plot for a L/R V-DOSC + flown SB218 system with LL/RR dV-DOSC offstage fill... 91 Figure 68: Stereo dV-DOSC offstage fill system.

  • Page 10: List Of Tables

    Figure 106: Constructive interference rings for a condensed point source line array........146 Figure 107: Destructive interference rings out of beamwidth for condensed and standard line arrays ..147 Figure 108: Front view of V-DOSC array and vertically stacked DOSC waveguides ........148 Figure 109: Horn Generated Wavefronts...................... 149 Figure 110: DOSC Waveguide –...

  • Page 11: Introduction

    If all of the individual pebbles could be glued together, this would provide the same effect as the larger stone... This illustrates the thinking behind V-DOSC: if we can build a single sound source from a number of individual speakers that can be separated for transport and handling, then we have achieved our goal, i.e., to create a modular sound reinforcement system where the individual loudspeaker enclosures...

  • Page 12: Wavefront Sculpture Technology Background

    Figure 1: Wavefront interference for a conventional sound reinforcement system compared to a sculptured V-DOSC wavefront WAVEFRONT SCULPTURE TECHNOLOGY BACKGROUND As early as 1988, a preliminary system named "Incremental" had proven the feasibility of Wavefront Sculpture Technology. From this experimental concept, further theoretical research was conducted by Professor Marcel Urban and Dr.

  • Page 13: Figure 2: Wavefront Sculpture Technology Conditions 1 And 2 Illustrated

    5) Limits exist concerning the vertical height of each enclosure, the minimum allowed listener distance and the angles that are allowed between enclosures. The key to satisfying WST conditions at higher frequencies is a proprietary L-ACOUSTICS waveguide ® that is used to load a conventional compression driver. This DOSC waveguide was invented by Dr.

  • Page 14: V-Dosc: The Solution

    One of the key benefits of WST is the predictability of the radiated wavefront's shape. Horizontally, the entire V-DOSC array has the same coverage as a single enclosure (90°). Vertically, the coverage is equal to the sum of the angles used between individual enclosures of the array. Given this predictability, vertical coverage can be quickly optimized to match the audience geometry using either L-ACOUSTICS ARRAY or SOUNDVISION software.

  • Page 15: Figure 3: Coplanar Symmetry Of V-Dosc

    Either we respect WST criteria to obtain coherent coupling between individual sources and create a single coherent line source (as for V-DOSC, dV-DOSC, KUDO, ARCS) or we separate individual, coherent sources (MTD or XT coaxial loudspeakers) in a manner so that desired audience coverage is achieved while the effects of audible interference are reduced.

  • Page 16: Figure 4: Cylindrical Versus Spherical Wave Propagation

    Apart from coverage precision and predictability, another significant benefit of V-DOSC is the fact that the system effectively extends the nearfield region at higher frequencies (the nearfield is defined as the region where cylindrical wavefront propagation applies and the farfield is the region where spherical wavefront propagation occurs –...

  • Page 17: Figure 5: V-Dosc Array

    Monitor engineers also enjoy working with V-DOSC FOH systems since there is very little backwave on stage - even at lower frequencies (for larger arrays of up to 16 enclosures, vertical pattern control is obtained down to as low as 80 Hz).

  • Page 18: V-Dosc Training And Qualifications

    V-DOSC Trainer. To be included in the official list that is distributed to members of the V-DOSC Network, the CVE ♦ Participated in a 3 day V-DOSC training session on theory and rigging candidate must meet the following criteria: ♦...

  • Page 19: The V-Dosc System Standard

    Figures 6-8. Please refer to these block diagrams for a system overview. NOTE: V-DOSC systems that do not comply with the system standard are considered non-approved by L- ACOUSTICS. For the case of non-standard systems, L-ACOUSTICS does not accept responsibility for misuse or misoperation and in some cases warranty coverage may be considered void.

  • Page 20: Figure 6: V-Dosc System Block Diagram

    Figure 6: V-DOSC System Block Diagram L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 20 of 158...

  • Page 21: Figure 7: Lr System Configuration

    Figure 7: Example LR System Configuration L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 21 of 158...

  • Page 22: Figure 8: Lr System Plus Offstage Fill Configuration

    Figure 8: Example LR System Plus Offstage Fill Configuration (additional distributed front fill or stereo infill system recommended) L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 22 of 158...

  • Page 23: V-Dosc System Components

    Used with V-DOSC for down-fill, up-fill/long-throw, offstage fill, stereo in-fill or distributed front fill. Note: for full details, see the dV-DOSC user manual (available for download on: www.l-acoustics.com) (4) FLIGHT-dV Flight case for transport of three dV-DOSC enclosures...

  • Page 24: Rigging Accessories

    RIGGING ACCESSORIES BUMP2 Flying bumper for rigging a V-DOSC array up to 16 enclosures deep. Can also be inverted and used as an adjustable base for stacking a V-DOSC array BUMPDELTA Delta plate used to attach two motors to BUMP2, allowing for pan adjustment of a flown V-...

  • Page 25: Figure 10: V-Dosc Rigging Accessories

    CHARIOT dV-DOWN dV-BUMP Figure 10: V-DOSC Rigging Accessories L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 25 of 158...

  • Page 26: Subwoofer Enclosures

    Protective cover for dV-SUB enclosures (comes in pairs) SB218 dV-SUB dVSUB COV SUB COV Figure 11: V-DOSC Subwoofer Options SUBWOOFER RIGGING ACCESSORIES (16) BUMPSUB Flying bar for rigging up to eight SB218 enclosures deep in a vertical line array (17) dV-BUMP2...

  • Page 27: Amplification

    Compact, light weight two-channel power amplifier (2 rack units, 10 kg), 1300 watts per channel into 8 ohms, 2300 watts per channel into 4 ohms. Figure 13: L-ACOUSTICS LA48a Power Amplifier Note: for full details see the LA48a user manual (available for download on: www.l-acoustics.com) AMPLIFIER RACKS (19) RK12U 12 rack unit amplifier rack (empty).

  • Page 28: Figure 14: Amplifier Rack Options And Accessories

    PADOSEC RK12U PADO2a COMB CONNECTOR RK122a PADO4a RK124a Figure 14: Amplifier Rack Options and Accessories L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 28 of 158...

  • Page 29: Signal Distribution And Cabling

    (used as a LINK cable breakout for patching and testing purposes). Note: Parts nomenclature is as follows: DOM = DOSC Modulation DOMP = DOSC Modulation Prolongateur (French for extender) L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 29 of 158...

  • Page 30: Figure 15: Signal Distribution And Cabling

    CO24 CONTROL OUTPUT CO6 CONTROL OUTPUT MC28100 MULTI DOM2 AMP LINK DOM30 CROSS LINK DOMF LINK BREAKOUT DOMM LINK BREAKOUT PCMCIA CARD DOMP LINK EXTEND Figure 15: Signal distribution and cabling L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 30 of 158...

  • Page 31: Loudspeaker Cabling

    LOUDSPEAKER CABLING (36) DO.7 V-CABLE V-DOSC loudspeaker cable, 8 conductor, 4 mm conductor cross-section, 0.7 m (2 ft) length, equipped with male/female CA-COM connectors (for parallel connection of V-DOSC enclosures) (37) DO7 V-CABLE V-DOSC loudspeaker cable, 8 conductor, 4 mm...

  • Page 32: Figure 16: Loudspeaker Cabling Options

    DO.7 V-DOSC LINK CABLE DO7 V-CABLE DO25 V-CABLE DOSUB CABLE DO10P EXTENSION SP.7 SP25 DO3WFILL DOFILL DO2W DO3W CC4FP Figure 16: Loudspeaker cabling options L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 32 of 158...

  • Page 33: V-Dosc Specifications

    8-pin connectors. Although V-DOSC is a 3-way design, the enclosure is powered by 4 amplifier channels. Enclosures are connected to amplifier racks using V-CABLEs (7 m or 25 m length, as required) that are equipped with 8 pin Cannon CA-COM connectors of the bayonet-locking type.

  • Page 34: V-Dosc Rigging System

    BUMP2 flying structure in a train-like fashion. Two recessed Aeroquip flytrack sections are mounted on both sides of the enclosure and two rear-mounted rotating legs allow up to 16 V-DOSC to be assembled in a vertical column. Angle straps are attached between enclosures using the side flytrack sections to provide up to a maximum of 5.5 degrees between enclosures at 0.75 degree angular...

  • Page 35: Sb218 Subwoofer Specifications

    A unique feature of the V-DOSC rigging system is the fact that the relative action of the front and rear chain motors can be used to adjust the vertical site angle of the entire array. The rear rotating legs of the entire assembly provide the mechanical connection and bear the majority of the load while the angle straps determine the angle between adjacent V-DOSC enclosures.

  • Page 36: Figure 20: Sb218 Subwoofer - Front And Rear Views

    106 kg (234 lbs) Figure 20: SB218 Subwoofer – Front and Rear Views With the addition of SB218 subwoofers, the low frequency response of the V-DOSC system is extended down to 25 Hz. The SB218 subwoofer enclosure has been specifically designed to complement V-DOSC and all OEM factory presets are optimized for the SB218.

  • Page 37: Sb218 Rigging System

    Shackles and double stud fittings are then attached every 13 chain links, i.e., with a separation of 11 open chain links between each shackle as shown in the figure below. Figure 21: BUMPSUB SB218 Flying Bar L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 37 of 158...

  • Page 38: Powering V-Dosc

    V-DOSC, 2 enclosures in parallel is the optimum load while 3 is more cost-effective. Powering 3+3 V-DOSC enclosures is safe for the amplifiers, but does not provide the same standard of sonic quality due to reduced headroom - particularly for the mid and high sections (see Table 2 below).

  • Page 39: Table 2: Load And Power Ratings For V-Dosc

    (0 dB) (0 dB) Note: L-ACOUSTICS recommends that LA48a Channel A/B MLS switches are in the 0 dB position and Channel A/B CLIP LIMITERS are enabled (rear panel switch=IN) at all times. As standard, the L-ACOUSTICS LA48a power amplifier has 32 dB gain.

  • Page 40: V-Dosc Amp Panels

    Figure 23: V-DOSC PADO2a Amplifier Rack Panel The V-DOSC PADO2a amp panel is suitable for use with 2 LA48a power amplifiers and allows for connection of loudspeakers, input signal and output signal loop through. The panel has a single female 8 pin CA-COM connector for loudspeaker connection that is in parallel with 4 x Speakon NL4 connectors;...

  • Page 41: Figure 24: Pado4A Amp Rack Wiring

    Table 3: PADO4a COMB Wiring Chart Table 4: PADO4a Internal Amp Rack Wiring Chart Figure 24: PADO4a amp rack wiring L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 41 of 158...

  • Page 42: Figure 25: Pado2A Amp Rack Wiring

    Table 5: PADO2a COMB Wiring Chart Table 6: PADO2a Internal Amp Rack Wiring Chart Figure 25: PADO2a amp rack wiring L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 42 of 158...

  • Page 43: V-Dosc Amplifier Racks

    Figure 26: L-ACOUSTICS Amplifier Rack RK124a loaded with 4 x L-ACOUSTICS LA48a amplifiers The L-ACOUSTICS amplifier rack RK12U is 12 rack units high and can be loaded with up to 4 L- ACOUSTICS LA48a amplifiers and the PADO4a amp rack panel. Overall external dimensions are 77 cm high (including casters) x 61 cm wide x 58 cm deep (30.3 x 26.4 x 22.9 inches).

  • Page 44: Figure 27: L-Acoustics Amplifier Rack Options

    Master Rack Slave Rack Figure 27: L-ACOUSTICS Amplifier Rack Options: (a) 4x LA48a plus PADO4a; (b) 4x LA48a plus 2x PADO2a; (c) Master Rack with DSP, CO6 Control Output, 2x LA48a, PADO2a; (d) Slave Rack with 2x LA48a, PADO2a L-ACOUSTICS V-DOSC Manual Version 4...

  • Page 45: Comb Connectors

    PADO4a amplifier rack panels to the appropriate amplifier inputs. Amplifier racks can be conveniently reconfigured without rewiring internally - simply by changing the COMB connector. COMB connectors for use with V-DOSC (4-way+2 or 5-way+1 format presets) are: DSUB = SUB...

  • Page 46: Figure 28: L-Acoustics Rk122A Amplifier Rack Channel Assignments And Cabling

    Operating modes, amplifier rack channel assignments and cabling plus loudspeaker enclosure combinations for the L-ACOUSTICS RK122a amplifier rack (PADO2a plus 2 x LA48a) are as follows: V-DOSC HI V-DOSC LO 2W HI 2W HI V-DOSC MID V-DOSC LO 2W LO...

  • Page 47: Figure 30: L-Acoustics Rk122A Amp Rack Channel Assignments For 2-Way, 3-Way Stereo Presets

    DSP outputs when changing between stereo 2-way and 3-way presets. Operating modes, amplifier rack channel assignments and cabling plus loudspeaker enclosure combinations for the L-ACOUSTICS RK122a amplifier rack (PADO2a plus 2 x LA48a) are as follows: 2-WAY STEREO PRESETS...

  • Page 48: Figure 31: L-Acoustics Rk124A Amp Rack Channel Assignments For 2-Way, 3-Way Stereo Presets

    Operating modes, amplifier rack channel assignments and cabling plus loudspeaker enclosure combinations for the L-ACOUSTICS RK124a amplifier rack (PADO4a plus 4 x LA48a) are as follows: 2-WAY STEREO PRESETS RK124 RK124 HI (A) HI (A) HI (A) HI (B) LO (A)

  • Page 49: Co24 Control Output Panel

    SB218 subwoofers. Therefore, each L-L, L, R and R-R array requires 6 drive channels: 3 for V-DOSC, 2 for dV-DOSC and 1 for SB218s. Since there are 4 arrays, this requires 24 drive channels total. The 84 pin Whirlwind MASS W6 connector accomodates these 24 drive channels (72 lines) leaving 14 additional lines available.

  • Page 50: Md24 Multi Distro Panel

    The CO6 Control Output panel allows for maximum flexibility while providing a scaleable architecture that can be used for small, medium and even large system applications since it is compatible with the dV-DOSC and V-DOSC signal distribution strategy and cabling/connector standards. Figure 34: CO6 Control Output Panel...

  • Page 51: Approved Digital Signal Processors

    … The bottom line is that making sure that V-DOSC is used properly is in everyone’s best interest and it is up to the Qualified V-DOSC Technician and Certified V-DOSC Engineer to maintain quality control standards.

  • Page 52: V-Dosc Presets

    3-way presets are available (X and INFRA). There are four basic operating modes when V-DOSC is used with SB218 subwoofers as a 4-way system (X, XAUX, INFRA, 4W) and for extra impact, dV-SUB subwoofers can be added to create a 5-way system (X, INFRA modes).

  • Page 53: Lo/Hi Presets

    LO/HI PRESETS V-DOSC presets come in pairs (LO = smooth, HI = bright) and there is a 3 dB difference in HF shelving eq between LO and HI presets. In addition to the HF shelving eq difference, for V-DOSC V7 LO presets, the mid/high section output gains have been scaled up by 2 dB in order to: provide a flatter overall response curve for classical music and speech reinforcement;...

  • Page 54: 4-Way Presets

    SUB/LOW GAIN SCALING PROCEDURES The Version 7 preset release has been optimized for a 1.5 : 1 cabinet ratio of V-DOSC : SB218 (for example, 3:2, 6:4, 9:6, 12:8, 15:10). As a starting point, output channel gains for a 3:2 V-DOSC:SB218...

  • Page 55: Infra Preset

    Although the 80 Hz HPF for the V-DOSC low section does not fully utilize V-DOSC low end resources, subjectively, the low end can sound “tighter” due to the 80 Hz crossover point (but this is a matter of personal taste and program material). Venue acoustics can also be a factor in selecting between INFRA and 4W presets –...

  • Page 56: Preset

    The X preset features the same operating bandwidth for SB218 subwoofers and the V-DOSC low section (SB218 = 25-200 Hz, V-DOSC low = 30-200 Hz). X presets take full advantage of the available power resources of the V-DOSC low section and are intended for closely coupled applications where SB218 subwoofers are installed in close physical proximity to V-DOSC (flown beside or stacked directly underneath as an extension of the system).

  • Page 57: 5-Way Presets

    5-WAY PRESETS To enhance low end impact of the flown V-DOSC system, dV-SUB subwoofers can be flown beside V-DOSC (with minimum physical separation) and used in conjunction with ground-stacked SB218 subwoofers to create a 5-way system. The dV-SUBs are run over the same operating bandwidth as the V-DOSC low section and two preset types exist (X, INFRA).

  • Page 58: General Guidelines Regarding System Protection

    Limiter thresholds are user accessible and exact settings will depend on individual engineer preferences and the type of music or application which, in turn, determines how hard the V-DOSC system is being operated. When additional protection is desirable, limiter thresholds can be lowered...

  • Page 59: Xta Dp224 V-Dosc Presets

    2-way mono sub SB218 (A+B) SB218 (A) MONO (A+B) SB218 (B) SB218 LCR 80 Hz 2-way mono sub SB218 (A+B) SB218 (A) MONO (A+B) SB218 (B) Table 11: XTA DP224 Presets L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 59 of 158...

  • Page 60: Xta Dp226 V-Dosc Presets

    SB218 (A) V-DOSC LO (A) V-DOSC MID (A) V-DOSC HI (A) dV-DOSC LO (B) dV-DOSC HI (B) V-DOSC i AUX + dV LO 5-way (A) + 1 (B) V-DOSC LO (A) V-DOSC MID (A) V-DOSC HI (A) dV-DOSC LO (A)

  • Page 61: Lake Contour V-Dosc Presets

    V-DOSC X HI SB218 (A) V-DOSC LO (A) V-DOSC MID (A) V-DOSC HI (A) FULL (A) V-DOSC i AUX + dV LO V-DOSC LO (A) V-DOSC MID (A) V-DOSC HI (A) dV-DOSC LO (A) dV-DOSC HI (A) V-DOSC i AUX + dV HI...

  • Page 62: Bss Fds 366 V-Dosc Presets

    BSS FDS 366 V-DOSC PRESETS PRESET NAME PGM TYPE OUT 1 (Source) OUT 2 (Source) OUT 3 (Source) OUT 4 (Source) OUT 5 (Source) OUT 6 (Source) USER 3(A)+3(B) V 3W i LO 3(A)+3(B) V-DOSC LO (A) V-DOSC MID (A)

  • Page 63: V-Dosc Coverage Modeling

    2.1 COVERAGE IN THE HORIZONTAL PLANE V-DOSC has a coverage angle of 90° in the horizontal plane from 630 to 12.5k Hz with -6 dB points at +/- 45° off-axis. Horizontal coverage is independent of both the number of arrayed V-DOSC enclosures and the vertical configuration of the array.

  • Page 64: Coverage In The Vertical Plane

    Appendices 5 and 6 for more details). Since V-DOSC is, in essence, more efficient at projecting HF energy than LF, the net result is that for large distances, the tonal balance is progressively tilted by a HF enhancement. For longer throw...

  • Page 65: Constant Curvature V-Dosc Array

    (N-1) x A°, this type of array is of practical use only when the entire audience is sitting at the same distance from the array. However, in most venues, a V-DOSC array will have to cover an...

  • Page 66: Variable Curvature V-Dosc Array

    Variable Curvature V-DOSC Array Since individual V-DOSC enclosures radiate a flat, isophasic wavefront it is possible to focus energy in a given direction and increase the SPL by reducing the angles between enclosures. Conversely, by increasing the angle between enclosures (up to a maximum of 5.5°) it is possible to lower the SPL in another direction.

  • Page 67: Cutview Sheets

    (Cutview 2). Typically the second cutview is taken at 45° offstage (corresponding to the -6 dB coverage angle of V-DOSC) in order to confirm coverage throughout all parts of the audience. The ear height relative to floor level should be entered in the “listening level”...

  • Page 68: Figure 46: Parameters For The Room Dim Utility Sheet In Array

    For dV-DOSC upfill simulation, an autofocus adjust angle of zero degrees corresponds to the first dV-DOSC enclosure as parallel to the site angle of the top V-DOSC. To obtain the 0 degree relative angle, the 3.75 degree hole on dV-ANGLEP1 must be used ruring installation. For upfill purposes, the 5.5 or 7.5 degree holes can also be selected on dV-ANGLEP1.

  • Page 69: Optimization Procedure

    The cutview display shows the intersection of individual V-DOSC enclosure site angles with the audience (square blocks = site angle impacts) and represents the dispersion of SPL over the audience. In accordance with WST Condition #4, the best results are achieved when enclosure site angle impacts have equal spacing between them.

  • Page 70: Output Data

    (throw distance) for each enclosure are tabulated. Note: The site angle for enclosure #1 is essentially equal to the V-DOSC bumper site angle since the first enclosure is attached to the BUMP2 with minimum separation (within physical tolerance limits) using the BUMP angle strap.

  • Page 71: Figure 48: Array 2004 Geometric Data For V-Dosc

    Figure 48: ARRAY 2004 Geometric Data for V-DOSC The Nominal Vertical Coverage Angle of the array is calculated as the sum of the entered inter- enclosure angles. This coverage becomes effective at F and for all frequencies higher than F , the vertical coverage angle is less than this nominal vertical coverage angle.

  • Page 72: Dv-Array1, Dv-Array2 Input Data

    3) Calculation of the FRONT LOAD is within 20% error. When the front motor load goes to zero, Minimum Site Angle is displayed. 4) 2-LEG STRESS refers to the stress on the V-DOSC BUMP2 bumper’s rotating legs and is accurate within 20% error. NOTE: the effect of rear ratchet straps is not taken into account.

  • Page 73: Figure 49: Array 2004 Geometric Data For Dv-Dosc

    Figure 49: ARRAY 2004 Geometric Data for dV-DOSC L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 73 of 158...

  • Page 74: H-Isocont Sheet

    L, R arrays illustrates which portions of the audience will experience stereo imaging. Note: It is not possible to simulate the transition between dV-DOSC to V-DOSC isocontours in ARRAY 2004 when dV-DOSC is used for downfill or upfill in conjunction with V-DOSC. In order to simulate this transition, SOUNDVISION is recommended.

  • Page 75: Figure 50: Array 2004 Spreadsheet Calculation Example

    CUTVIEW SHEET HORIZONTAL ISOCONTOUR SHEET Figure 50: ARRAY 2004 spreadsheet calculation example L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 75 of 158...

  • Page 76: V-Dosc Coverage Modeling Using Soundvision

    12 V-DOSC enclosures (angles top-to-bottom = 4,4,4,4,4,4,4,4,4,4,3). For this example, the V-DOSC array is perpendicular to a target plan having dimensions of 35 x 100 metres at a 30 metre throw distance (imagine the V-DOSC array firing at a large wall). Coverage is seen to be stable and well-defined above 1 kHz while becoming progressively more omnidirectional at lower frequencies.

  • Page 77: Figure 51: Soundvision Geometric Data For V-Dosc

    Note: For color versions of SOUNDVISION figures see the V-DOSC manual PDF file available for download www.l-acoustics.com Note: A complete description of SOUNDVISION is beyond the scope of this manual.

  • Page 78: Figure 52: Plan View Spl Mappings At Octave Band Frequencies For 12 V-Dosc

    8 kHz 1 kHz 2 kHz 10 kHz Figure 52: Plan view SPL mappings at octave band frequencies for 12 V-DOSC (30 metre throw distance, enclosures perpendicular to target plane) L-ACOUSTICS V-DOSC Manual Version 2.00 29/06/05 V-DOSC MANUAL V4 0605.doc...

  • Page 79: Figure 53: Impact Coverage And Spl Mappings For 12 V-Dosc

    Unweighted SPL Map A Weighted SPL Map 1-10 kHz SPL Map Figure 53: Impact coverage and SPL mappings (unweighted, A-weighted, 1-10 kHz bandwidth) for 12 V-DOSC (30 metre throw distance, enclosures perpendicular to target plane) L-ACOUSTICS V-DOSC Manual Version 2.00 29/06/05 V-DOSC MANUAL V4 0605.doc...

  • Page 80: Soundvision Examples

    The following SOUNDVISION example (Amsterdam Arena, NL) shows the coverage of different elements of a stadium system consisting of: four main arrays (15 V-DOSC + 3 dV-DOSC); four distributed front fill arrays (3 dV-DOSC); one centre cluster (6 dV-DOSC); eight distributed balcony fill arrays (6 dV-DOSC).

  • Page 81: Figure 55: Stadium Example - Rear Perspective View Of 1-10 Khz Spl Mappings

    FOH SYSTEM: L, R FRONT FILL SYSTEM: 4 x 3 dV-DOSC OFFSTAGE FILL SYSTEM: LL, RR Figure 55: Stadium example - rear perspective view of 1-10 kHz SPL Mappings L-ACOUSTICS V-DOSC Manual Version 2.00 29/06/05 V-DOSC MANUAL V4 0605.doc 81/158...

  • Page 82: Soundvision Arena Example

    DOSC + 3 dV-DOSC); two offstage fill arrays (12 dV-DOSC); eight distributed front fill enclosures (112XT). Figure 56: Arena example -rigging plot Figure 57: Arena example - plan view of full system impact coverage L-ACOUSTICS V-DOSC Manual Version 2.00 29/06/05 V-DOSC MANUAL V4 0605.doc 82/158...

  • Page 83: Figure 58: Arena Example - Rear Perspective View Of Full System Impact Coverage

    Figure 58: Arena example - rear perspective view of full system impact coverage Figure 59a: Arena example - rear perspective view of full system SPL map (1-10 kHz) L-ACOUSTICS V-DOSC Manual Version 2.00 29/06/05 V-DOSC MANUAL V4 0605.doc 83/158...

  • Page 84: Figure 59B: Arena Example - Plan View Of 1-10 Khz Spl Mappings

    Offstage LL/RR Full System 112XT Front Fill System FOH L/R Figure 59b: Arena example – plan view of 1-10 kHz SPL mappings L-ACOUSTICS V-DOSC Manual Version 2.00 29/06/05 V-DOSC MANUAL V4 0605.doc 84/158...

  • Page 85: Sound Design

    Note: For hybrid stacked/flown systems, the trim height of the flown system should be selected so that the bottom V-DOSC cabinet has a zero degree site angle and is at the same height as the listening level for the first row of the balcony audience. This helps avoid reflections from the balcony face while providing more even off-axis coverage for the first row of the balcony.

  • Page 86: Stacking Guidelines

    Stacking Guidelines The stacking system is rated for a maximum of 6 V-DOSC enclosures - always use angle straps between enclosures For stacked systems, the well-defined vertical coverage of V-DOSC allows little margin for error. Whether the audience is standing or seated is an important consideration and the system should be stacked on a riser of suitable height (or on top of subwoofers) so that the system is higher than the listening level of the first row of the audience.

  • Page 87: Flying Guidelines

    Flying Guidelines The rigging system is rated for a maximum of 16 V-DOSC or 15 V-DOSC + 3 dV-DOSC Particular attention must be paid to the height at which the array is flown when predicting the vertical coverage in ARRAY 2004 or SOUNDVISION. Typically, system trim height should be selected to...

  • Page 88: Achieving Optimum Coverage

    Although not the best technical solution, the left/right configuration meets both visual and practical criteria and is most commonly used. V-DOSC is a dramatic improvement over conventional systems but, by nature, the stereo imaging of any left/right system is limited for a large part of the audience and there are compromises with respect to the consistency of tonal balance in the horizontal plane.

  • Page 89: Left/Centre/Right (Lcr) Configurations

    Scovill (Live Sound International, Nov/Dec 2002). When using the LCR configuration for live music applications, three V-DOSC arrays can be installed with the C array at 0 degrees and the L/R arrays panned offstage up to 20 degrees (for speech reinforcement, L/R arrays can be panned offstage up to 70 degrees to optimize coverage and intelligibility).

  • Page 90: Multiple Array Concepts

    20 ft) from the first array. Figure 66: Generic rigging plot for a V-DOSC system consisting of main L/R FOH and LL/RR offstage fill arrays Given this separation, interference only occurs in the low frequency range and there are no audible intelligibility losses for the following reasons: 1) the first octave-wide comb filtering cancellation is shifted lower in frequency outside the V-DOSC low section’s operating bandwidth, for example, 24...

  • Page 91: Figure 67: Rigging Plot For A L/R V-Dosc + Flown Sb218 System With Ll/Rr Dv-Dosc Offstage Fill

    Figure 67: Rigging plot for a L/R V-DOSC + flown SB218 FOH system with LL/RR dV-DOSC offstage fill (dimensions in metres). See figure 60 for a “reduced footprint” version of this rigging plot. Experience has shown that this is a very flexible approach that can cover any type of audience and an additional advantage of multiple arrays is improved resistance to wind effects in open-air situations.

  • Page 92: Subwoofers

    V-DOSC system (separate auxiliary send). The other option is to use subwoofers as a low frequency extension of the V-DOSC array and drive subs with the same signal (4-way mode). All presets (4W, INFRA, X, X AUX) will function with aux sub drive or in 4-way mode, however, the user should be aware of the operating bandwidths and select the preset that is most appropriate for the installed configuration and application.

  • Page 93: Flown V-Dosc And Ground Stacked Subwoofers

    LCR Configuration Figure 69: Flown V-DOSC and ground stacked subwoofer configurations As illustrated in Figure 70, for flown V-DOSC and ground stacked subwoofer configurations, time alignment of subwoofers is required due to the geometric path difference between the two systems.

  • Page 94: Figure 71: Time Alignment Location For Flown V-Dosc, Ground Stacked L/R Subwoofers

    DELAY ARC 80 Hz or SB218 LCR 80 Hz presets (subs with negative polarity).The 3W INFRA preset features a 60 Hz HPF for the V-DOSC low section and SB218 DELAY ARC 60 Hz or SB218 LCR 60 Hz presets are recommended for aux sub drive (subs with positive polarity).

  • Page 95: Physically Coupled Subwoofers

    Optimum coupling between subwoofer and V-DOSC arrays is achieved by keeping the SB218 array physically close to the V-DOSC array. Two configurations are possible: 1) Fly the SB218 array on the offstage side, less than 3 metres from the V-DOSC array, axis-to-axis The benefits of flown subwoofers include: •...

  • Page 96: Hybrid Flown/Stacked Subwoofers

    Figure 74: Hybrid flown/stacked subwoofer example : L/R = 14 V-DOSC + 3 dV-DOSC (per side); flown dV-SUB (6 per side); ground stacked SB218 (6 per side); LL/RR = 4 V-DOSC + 6 dV-DOSC (per side); stereo infill = 2 dV-DOSC (per side);...

  • Page 97: Subwoofer Arraying Techniques

    In Figure 75 (a), ground stacked L/R subwoofers are arranged in a block with minimum frontal surface area and are physically separate from the flown V-DOSC arrays (either INFRA, 4W or X AUX presets are recommended). When subwoofers are configured in the manner (i.e., with minimum front surface...

  • Page 98: Figure 75: L/R Subwoofer Arraying Techniques

    (b) L/R column line arrays (a) L/R subwoofer array blocks (d) Curved L/R subwoofer arrays (c) L-Wrap L/R subwoofer arrays (e) L/R horizontal line arrays Figure 75: L/R Subwoofer arraying techniques L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 98 of 158...

  • Page 99: Central Line Array With Electronic Delay Processing

    - this is useful for venues where there is an audience tribune. Since the subwoofers are physically separate from the flown V-DOSC arrays they are normally driven via aux send in either INFRA, X AUX or 4W mode (although the system can also be operated in 4-way mode).

  • Page 100: Left/Centre/Right Configurations

    (i) time align L with respect to C with the measurement microphone on- axis to L at a distance where the SPL from C and L arrays is identical; (ii) time align V-DOSC FOH L with respect to L with the measurement microphone located between FOH L and ground stacked L subwoofers at a distance where the SPL from the low section of the flown system equals the SPL from the ground stacked subwoofers;...

  • Page 101: Figure 78: Lcr Subwoofer Arraying Techniques

    (c) Flown L/R, ground stacked C (d) Flown L/R, stereo infill C (e) Flown L/R, centre line array with electronic delay processing (f) Flown L/R, distributed ground stacked subwoofers Figure 78: LCR Subwoofer arraying techniques L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 101 of 158...

  • Page 102: Large Format Subwoofer Array Configurations

    It is recommended that arc radii remain shallow so that the difference between T3 and T4 remains less than 15 msec. Steeper arc radii will decorrelate LL versus L (and RR versus R) V-DOSC arrays to the extent that the LL array will be perceived as an echo with respect to the L array. Apart from...

  • Page 103: Figure 80: Geometric Coordinates For The Sub Arc Utility Spreadsheet In Array2004

    Figure 80: Geometric coordinates for the SUB ARC utility spreadsheet in ARRAY2004 Figure 81: Large format arena configuration – 4 delay taps (Rammstein World Tour 2004/5, Black Box Music) L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 103 of 158...

  • Page 104: Figure 82: Large Format Open Air Festival Configuration

    Figure 82: Large format open air festival configuration (Festival of Humanity, France, Potar Hurlant) Figure 83: Large format stadium configuration (Red Hot Chili Peppers 2004 European Tour, Rat Sound) L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 104 of 158...

  • Page 105: Complementary Fill Systems

    3.6 COMPLEMENTARY FILL SYSTEMS For flown V-DOSC configurations, additional speakers are typically necessary to cover center fill, front fill or offstage fill requirements and delay systems may be required for large format festival or stadium sound reinforcement. Apart from providing added coverage, an important sound design consideration...

  • Page 106: Offstage Fill

    3.6.2 OFFSTAGE FILL Good candidates for offstage fill include dV-DOSC, ARCS, KUDO or additional V-DOSC arrays. Selection between these options will depend on throw distance and vertical coverage requirements and the guidelines outlined in multiple arrays should be followed (Section 3.3). For offstage fill, the same principles for flown versus stacked systems apply (Section 3.2) and hybrid flown/stacked offstage...

  • Page 107: Delay Systems

    Figure 87 shows an outdoor festival system example for an audience area of 150 metres deep by 200 metres wide. The main L/R system consists of 16 V-DOSC per side and there are 12 V-DOSC for the LL/RR arrays. Four delay positions of 9 V-DOSC each are located on a circular radius 80 metres from the stage.

  • Page 108: Figure 88: Flown And Stacked Delay Systems

    Figure 88: Flown and stacked delay systems (sound design - D. Tramontani, A. Francais, resp.) Figure 89: Stacked dV-DOSC delay system (Dream Concert 2002, sound design - Ki Sun Choi, Seoul Sound) Figure 90: Flown V-DOSC delay system (Radiohead, Oxford 2003, sound design - F. Bernard) L-ACOUSTICS V-DOSC Manual Version 4...

  • Page 109: Installation Procedures

    For stability reasons, the maximum number of V-DOSC enclosures that can be stacked is 6 (total weight including the bumper is 709 kg or 1563 lbs). The V-DOSC BUMP2 bumper is used as a stacking platform and four corner screwjacks allow for tilt adjustment of the stacked system. Prior to...

  • Page 110: Table 15: Angle Strap Values

    Alternatively, from the highest section of the audience area, if you can see the top of the upper V-DOSC enclosure, you are out of the coverage pattern. Focus can also be performed by placing a laser on the upper wall of the top enclosure and a visual check should be made with respect to the lower wall of the bottom enclosure of the array to ensure that closest members of the audience are covered.

  • Page 111: Figure 91: Stacked V-Dosc Offstage Fill System

    When stacking on scaffold platforms, install 2 rear screwjacks only (for downwards tilt) and ratchet strap the BUMP2 to the platform for improved stability (see Figure 91) Figure 91: Stacked V-DOSC offstage fill system (Radiohead, Oxford 2003, sound design - F. Bernard) L-ACOUSTICS V-DOSC Manual Version 4...

  • Page 112: Flown System

    4.2 FLOWN SYSTEM Rigging a V-DOSC array is fast and easy, with significantly reduced handling time compared to conventional systems. Please refer to the photo sequence in Figure 94 with respect to the following description of flying procedures. Preliminary Preparations All installation data for rigging the array (i.e., bottom enclosure elevation, inter-enclosure angles,...

  • Page 113: Figure 93: Soundvision Installation Report Data

    Figure 93: SOUNDVISION installation report data Figure 94: ARRAY 2004 installation data L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 113 of 158...
  • Page 114 As a reference for cabinet orientation, enclosure stacking runners will be oriented upwards and rear jack plate V-DOSC logos will be upside down once the array is flown (see Fig 95 a). Enclosures are mechanically connected together using the rotating legs and U pins. Use the locking safety pins to secure all U pins in place.
  • Page 115 Raise the front motor to the same height as the rear motor to level BUMP2 and the top V-DOSC enclosure. Attach a laser and/or remote inclinometer on top of the first V-DOSC enclosure – use the enclosure as a reference for attaching these measurement instruments, not the bumper.
  • Page 116 L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 116 of 158...
  • Page 117 L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 117 of 158...
  • Page 118 L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 118 of 158...

  • Page 119: Figure 95: Photo Sequence Showing The Steps Involved In Flying V-Dosc

    (aa) (bb) (cc) (dd) Figure 95: Photo sequence showing the steps involved in flying V-DOSC L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 119 of 158...
  • Page 120 ♦ When ratchet straps are overtightened and the array is excessively tilted upwards, physical damage can result to the flytrack and/or angle strap fittings ♦ L-ACOUSTICS has developed a spacer block to eliminate the need for use of ratchet straps, (specifically for the case of arrays with upwards tilt) Moderately ratcheting flown arrays IS recommended for the following reasons: ♦...
  • Page 121 94). Once the proper height has been set, the rear motor is turned off and the front motor used to adjust the site angle of the top V-DOSC enclosure (-1.5 degrees in Fig 94 - see also below). SOUNDVISION installation data (see Figs 51 and 93): The front motor is used to set the elevation of the array and the rear motor controls the site angle.
  • Page 122 Under dark conditions (indoors), a laser pointer or laser level can be attached to the top of the upper V-DOSC enclosure. Trim angle adjustments are then given by the focus of the laser on the audience - no walking to the back of the venue is required although laser glasses or a set of binoculars can be useful in locating the laser beam).

  • Page 123: V-Dosc System Operation

    V-DOSC (without subwoofers) scales as follows: 1 V-DOSC (10 dB); 2 V- DOSC (13 dB), 4 V-DOSC (16 dB), 8 V-DOSC (19 dB), 16 V-DOSC (22 dB). As a result, for larger V-DOSC arrays (12-16 enclosures) the mid and high sections can both be increased by 3-6 dB (or the low section attenuated) to compensate for the enhanced low end coupling that occurs.
  • Page 124 FOH L/R arrays are correctly matched). In addition, a common problem with FOH engineers who are unfamiliar with V-DOSC is the tendency to over-equalize the mid section since they are unaccustomed to the nearfield listening experience over this frequency bandwidth. The CVE or QVT accompanying the V-DOSC system should attempt to dissuade over-equalization and educate the guest engineer whenever possible.

  • Page 125: Measurement Procedures

    (which can be disruptive to other people working on the installation). Note: For 5+1 format presets (V-DOSC INFRA, X, 4W), fullrange ouput 5 (input A) can be used to monitor the effects of input parametric equalization which is used for system eq.

  • Page 126: Measurement Tips

    Watch out for wind effects and be sure that measurements are stable and repeatable at high frequencies. L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 126 of 158...

  • Page 127: Step-By-Step Tuning Procedure

    ♦ Place a microphone on the floor (at your reference point of choice) on-axis or equidistant between the left V-DOSC and left subwoofer arrays (alternatively, time alignment measurements can be conducted on FOH R). For LCR subwoofer arrays, refer to Section 3.5.3 for recommendations concerning measurement microphone locations for time alignment ♦...
  • Page 128 Voice the system with a good quality vocal microphone. 20) Verify tuning throughout the audience by walking the room and perform final adjustments using the analyzer between your ears! L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 128 of 158...

  • Page 129: Maintenance And Installation Tools

    Periodic maintenance procedures (every 6-12 months) include: tighten dolly locator pins and all external fasteners on V-DOSC and SB218 enclosures tighten high frequency diaphragm mounting fasteners inspect all rigging components for wear and replace as necessary (i.e., rotating legs,...

  • Page 130: Spare Parts

    Neoprene glue for grille foam attachment CD COLNEO Brown paint (packaged by 10 kg) CD TEXTURE Dust filter clips for LA48a APCLIP Dust filters for LA48a APFILT Rear support kit for LA48a amplifier APSUP L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 130 of 158...

  • Page 131: Recommended Installation Tools

    SOUNDVISION, Excel (for ARRAY 2004), WinMLS, SMAART or MLSSA measurement software, sound card, measurement mic/preamp, DSP control/programming software (Lake Contour, XTA Audiocore, BSS Soundbench2, BSS Soundweb) Figure 96: Recommended Installation Tools L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 131 of 158...

  • Page 132: Specifications

    7. SPECIFICATIONS 7.1 V-DOSC ENCLOSURE SPECIFICATIONS The specifications for one individual V-DOSC enclosure are given below. These individual enclosure specifications are not relevant to V-DOSC system performance since overall system behavior is the net result of the complex acoustical coupling between all enclosures of the array.

  • Page 133: Figure 97: V-Dosc Enclosure - Line Drawing

    Figure 97: V-DOSC Enclosure – Line Drawing L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 133 of 158...

  • Page 134: Sb218 Subwoofer Specifications

    1300 mm x 550 mm x 700 mm (51.2" x 21.7" x 27.6") 106 kg (233 lbs) Weight: + 9,5 kg (21 lbs) for dolly Figure 98: SB218 Subwoofer – Line Drawing L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 134 of 158...

  • Page 135: Rigging Structures

    V-DOSC BUMP2 Bumper Dimension (WxHxD): 1262 mm x 140 mm x 1100 mm (49-5/8" x 5-4/8" x 43-3/8") 61.5 kg (135.6 lbs) Weight: Figure 99: V-DOSC Flying Bumper – Line Drawing L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 135 of 158...

  • Page 136: Sb218 Bumpsub Rigging Bar

    Table 16: Weights for flown V-DOSC system Number of Cabinet Bumper TOTAL TOTAL V-DOSC Weight Weight Weight Weight Cabinets (kg) (kg) (kg) (lbs) 1087 1325 1563 1801 2039 1033 2277 1080 1141 2515 1188 1249 2754 1296 1357 2992 1404...

  • Page 137: Co24, Md24 Line Assignment Summary

    REMOTE IN = 4 pin FEMALE XLR on front panel REMOTE IN = 4 pin FEMALE XLR on front panel (control signal from computer to amplifiers) (return signal from amplifiers to computer) L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 137 of 158...

  • Page 138: Co24 Control Output Panel Line Assignments

    LEFT YELLOW 2-WAY FILL LF LEFT 2-WAY FILL LF LEFT BLUE REMOTE M 4pin XLR ORANGE REMOTE M 4pin XLR BROWN REMOTE M 4pin XLR ORANGE REMOTE M 4pin XLR L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 138 of 158...

  • Page 139: Table 18B: Co24 W6 Socket Assignments

    RIGHT-RIGHT BROWN 2-WAY FILL LF RIGHT-RIGHT 2-WAY FILL LF RIGHT-RIGHT BROWN REMOTE F 4pin XLR YELLOW REMOTE F 4pin XLR ORANGE REMOTE F 4pin XLR YELLOW REMOTE F 4pin XLR L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 139 of 158...

  • Page 140: Md24 Multi Distro Panel Line Assignments

    2-WAY FILL LF RIGHT-RIGHT 2-WAY FILL LF RIGHT-RIGHT BROWN REMOTE M 4pin XLR #1 YELLOW REMOTE M 4pin XLR #2 ORANGE REMOTE M 4pin XLR #3 YELLOW REMOTE M 4pin XLR #4 L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 140 of 158...

  • Page 141: Table 19B: Md24 W6 Socket Assignments

    2-WAY FILL LF LEFT BLUE REMOTE IN F 4pin XLR #1 ORANGE REMOTE IN F 4pin XLR #2 BROWN REMOTE IN F 4pin XLR #3 ORANGE REMOTE IN F 4pin XLR #4 L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 141 of 158...

  • Page 142: Appendix 1: Why Do Separated Sound Sources Interfere

    +1)π = -1. As a result, pressure cancellation occurs for frequencies that satisfy the condition: 2f δd/c = 2n + 1 where n is an integer. L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 142 of 158...

  • Page 143: Figure 102: Comb Filtering Due To Path Length Differences Between Sources

    As discussed in Section 3.3, the principles of 2 source interference can be used in sound design when considering multiple V-DOSC arrays since, in effect, the main and offstage V-DOSC arrays act as 2 coherent sound sources. When a separation of 6-8 metres is maintained between the 2...

  • Page 144: Appendix 2: Further Explanations Regarding Wst Criteria

    + λ/2) then they do not cause cancellation – they couple constructively. If sources are expression for the path length difference. If adjacent sources are inside the ring defined by outside the ring they may cause cancellation. L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 144 of 158...

  • Page 145: Figure 104: The Effect Of Varying Frequency And Listener Position M On Fresnel Rings

    Figure 105. White areas are constructive interference zones. Figure 105: Destructive and constructive interference rings for a line array at observation point M. L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 145 of 158...

  • Page 146: Figure 106: Constructive Interference Rings For A Condensed Point Source Line Array

    Clear separation between coherent and incoherent wave-fields defines the consistency of the main coverage region. Figure 106: Constructive interference rings for a condensed point source line array at observation point L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 146 of 158...

  • Page 147: Figure 107: Destructive Interference Rings Out Of Beamwidth For Condensed And Standard Line Arrays

    C. Heil, M. Urban, “Sound Fields Radiated by Multiple Sound Source Arrays”, preprint #3269, presented at the 92 AES Convention, Vienna, March 24-27, 1992 M. Urban, C. Heil, P. Bauman, ''Wavefront Sculpture Technology'', Journal AES Vol. 51, No. 10, October 2003 L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 147 of 158...

  • Page 148: Appendix 3: How Does V-Dosc Behave With Respect To Wst Criteria

    HOW DOES V-DOSC BEHAVE WITH RESPECT TO WST CRITERIA The second Wavefront Sculpture Technology criterion: STEP < smallest λ/2 over the frequency range of operation is fulfilled by a V-DOSC array at low and mid frequencies. With reference to Figure 108, corresponding to λ/2 = 0.85 m.

  • Page 149: Appendix 4: How Does The Dosc Waveguide Work

    DOSC waveguide provides less than 4 mm of curvature at this frequency. DOSC waveguide technology is patented on an international basis. (n°0331566 in Europe, n°5163167 in North America). L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 149 of 158...

  • Page 150: Appendix 5: The Border Between Fresnel And Fraunhofer Regions

    In the Fresnel region, the wavefront is cylindrical and expands only in the horizontal dimension (nominally 90° for V-DOSC). The height of the wavefront is equal to the height of the array. In the Fraunhofer region, the wavefront is spherical and expands in both horizontal & vertical dimensions.

  • Page 151: Figure 112: Illustration Of Dborder And Dv For A Flat 12 Enclosure Array

    (deg) (deg) At 1 kHz a flat V-DOSC array of 8 enclosures (H=3.6 m) radiates a wavefront that is cylindrical over a distance of 19 m. Beyond this distance, the wavefront becomes spherical, and the coverage angle is 6° (i.e., the wavefront at 1 kHz is defined by the height of the array up to 19m and broadens by +/-3°...

  • Page 152: Appendix 6: Pattern Control Of A Constant Curvature Array

    For frequencies higher than F , the vertical coverage angle is constant. For example, a constant curvature array of 8 V-DOSC with 4° between all enclosures provides constant 28° vertical coverage above F = 794 Hz, with narrower coverage at F...

  • Page 153: Appendix 7: Wst Criteria Number 5

    11,7 dmin = 10 m dmin = 20 m For front-loaded 15” systems such as V-DOSC, it is seen that the maximum allowed angle is 4.8 degrees for d = 10 m and 6.0 degrees for d = 20 m. This explains why the maximum ANGLE STRAP value for V-DOSC is 5.5 degrees.

  • Page 154: Appendix 8: Angle Strap Calibration

    When testing angle straps, they should fit the test jig with a tolerance variation of +1 mm to +2 Note: For full details on angle strap calibration issues refer to “Technical Bulletin TB0402 Angle Straps” Figure 114: Angle strap calibration L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 154 of 158...

  • Page 155: Appendix 9: V-Dosc Rigging Certification

    APPENDIX 9: V-DOSC Rigging Certification L-ACOUSTICS V-DOSC Manual Version 2.00 29/06/05 V-DOSC MANUAL V4 0605.doc 155/158...
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