Martin audio WAVEFRONT COMPACT APPLICATIONS GUIDE

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The Martin Experience

Wavefront Compact Series

Applications Guide

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MARTIN AUDIO

LONDON

Wavefront Compact Series

MARTIN AUDIO - APPLICATIONS GUIDE, WAVEFRONT COMPACT SERIES

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Applications Guide

Contents

Introduction Wavefront Compact Series Overview

Section 1 W8C 3-way System

Section 2 W8CT & W8CM Line Array System

Section 3 W8CS Flown Subwoofer

Section 4 WSX Folded Horn Subwoofer

Section 5 W8L Series Line Array Systems

Appendix

A1 W8 3-way System A2 W8S Hybrid

Subwoofer

Introduction

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Wavefront Compact Series Overview

Thank you for purchasing a Martin Audio Wavefront Compact Series system.

Wavefront Compact Series products make up a coherent "toolkit" of compact, live sound enclosures covering a huge range of professional sound projects from high quality club installations to major touring and festival systems.

Unpacking

Each Martin Audio loudspeaker is built to the highest standard and thoroughly inspected before it leaves the factory. After unpacking the system, examine it carefully for any signs of transit damage and inform your dealer if any such damage is found. It is suggested that you retain the original packaging so that the system can be repacked at a future date if necessary.

Please note that Martin Audio and its distributors cannot accept any responsibility for damage to any returned product through the use of non-approved packaging.

Standards

Martin Audio Wavefront Compact Series products conform to the requirements of the EMC Directive 89/336/EEC, amended by 92/31/EEC and 93/68/EEC and the requirements of the Low Voltage Directive 73/23/EEC, amended by 93/68/EEC.

EMC Standards Applied: Emission EN55103-1:1996 Immunity EN55103-2:1996 Electrical Safety EN60065:1993

About this Applications Guide

This Applications Guide is based on Wavefront Compact field experience and general acoustical principles. We have provided information on the most popular system configurations and have included simple equations for those wishing to calculate the broadband coverage of their own cluster designs.

Going Further

Martin Audio Ltd manufactures a wide range of loudspeakers, system controllers and power amplifier. Visit our web-site at www.martin-audio.com for the latest product and applications news.

Cost effective rental

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The Martin Audio Wavefront Compact Series "tool kit" approach provides all the components required to assemble high quality, truck-friendly, quick deployment sound systems for applications ranging from small clubs, commercial and theatrical productions using floor placed W8Cs and W8CS’...

to vast outdoor events with flown Longthrow and W8C clusters:

Wavefront W8C systems are regularly used for audiences ranging from just a few

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hundred jazz devotees to thousands of arena concert-goers. Longthrow sections can increase touring system versatility even further and Longthrow/W8C combinations have been very successfully used to cater for festival audiences from hundreds of thousands to over two million at “Popestock” 2000.

The Wavefront Compact series includes both flown and floor-standing subwoofers. W8CS’ may be flown where floor space is limited by extensive set designs or TV camera tracks. Where floor space is available, Wavefront WSX folded horn subwoofers may be used to implement an all-horn sound system for maximum efficiency and projection.

Wavefront Compact system versatility satisfies rental companies' requirements to maximise stock utilisation without compromising performance and reliability.

Wavefront W8C 3-way System

The heart of the Wavefront Compact series is the award-winning W8C (Section 1), a compact, light weight, high performance, 3-way loudspeaker system that has been engineered to work as well in small, stand-alone set-ups as it does in large flown arrays.

A single Wavefront W8C cabinet will cover 55º horizontally x 30º vertically. The W8C polar response is well defined so that it may be arrayed for high power rock and dance applications in large venues. A smooth off-axis amplitude and phase response allows a wide range of intercabinet angles to be used for easy coverage tailoring.

All Wavefront Compact series cabinets are fitted with MAN load-certified flying points to minimise set-up time. These MAN fittings are designed to comply with the 12:1 safety factor specified by the German VBG70 standard when used with compatible MAN flying systems.

Wavefront Longthrow W8CT & W8CM Line Array System

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The Wavefront Longthrow W8CT & W8CM system (Section 2) is a compact, very powerful, light weight, multiple horn line array loudspeaker system whose cabinets have the same footprint and flying points as Wavefront W8C and W8CS systems.

Unlike odd-ball line arrays from other manufacturers, W8CTs and W8CMs have been designed to integrate seamlessly into the rest of the Wavefront family. The W8CM/CT combination may be rigged in continuous columns for high power, very long throw applications or may be used to complement regular W8C clusters by providing spot coverage for difficult seating areas.

The W8CT combines three horn-loaded high-mid drivers with six horn-loaded high frequency compression drivers. Like the award-winning W8C high-mid system, W8CT high-mid cone systems are optimally loaded to produce much lower distortion than typical waveguide-loaded compression drivers.

The W8CM has two vertically arrayed, low-mid horns to complement W8CT highmid/high systems with seamless amplitude and polar integration.

Like all Wavefront series trapezoidal products, W8CTs and W8CMs are fitted with MAN load-certified flying points and are designed to comply with the 12:1 safety factor specified by the German VBG70 standard.

Wavefront W8CS Flown Subwoofer

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The W8CS (Section 3) is a compact, light weight subwoofer that has the same cabinet footprint and flying points as the Wavefront W8C. It has been engineered to extend the W8C's performance to below 45Hz.

The W8CS comprises a special high excursion driver coupled to an efficient mid-bass horn and sub-bass port. This unique combination gives the W8CS the characteristic punch of a horn-loaded system with the low frequency bass extension of a reflex enclosure.

W8CS’ may be used as full bass subwoofers (up to120Hz) or may be flown as midbass sections (60-160Hz) to complement floor standing WSXs.

Wavefront WSX Folded Horn Subwoofer

The WSX folded horn subwoofer (Section 4) complements Wavefront Compact W8C touring systems to provide deep bass with maximum efficiency, speed and impact. It has a classic Martin ‘S’ shaped folded horn and couples a powerful, high excursion driver to the airload with a modified hyperbolic expansion law.

WSXs may be used as full bass subwoofers (up to120Hz) or as low-bass headroom extenders to complement flown W8CS sections configured for mid-bass.

DX1 Loudspeaker Management System

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The Martin Audio DX1 (Section 1.5) is a very high performance, 2 input/ 6 output DSP-based controller providing crossover, protection, delay and alignment functions. It comes with factory plug'n'play presets for a wide range of Martin Audio product configurations including the Wavefront Compact family. It is ideal for combining Wavefront Compact products into seamless systems.

For instance, two DX1s may be used to combine W8Cs, W8CS’ and WSXs to form a stereo, 5-way, active, all horn system for the ultimate performance and impact. One more DX1 may be used to add W8CT and W8CM Longthrow sections for difficult venues or large outdoor events.

The Martin Experience

Wavefront Compact Series

Applications Guide

Section 1

Wavefront W8C

3-Way System

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MARTIN AUDIO

LONDON

Section 1

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Wavefront W8C 3-Way System

Contents

1.1 Introduction

1.2 Specifications

1.3 Pin-outs and cabling

1.4 System patching

1.5 DX1 Loudspeaker Management System

1.6 Power amplifier recommendations

1.6.1 Martin Audio MA2.8 Power Amplifier Overview

1.7 General operational summary

1.8 Arraying and placement

1.9 Coverage calculations

1.10 W8Cs as front fills

1.11 W8Cs as side clusters

1.12 W8Cs in distributed (delay) systems

Wavefront W8C 3-Way System

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1.1Introduction

The award-winning Wavefront W8C 3-Way System is a very compact, light weight, high performance 3-way loudspeaker system in a trapezoidal cabinet. The Wavefront W8C integrates a horn-loaded 12" low-mid driver with a horn-loaded 6.5" high-mid driver and a horn-loaded 1" very high frequency compression driver. The 6.5" highmid cone driver provides a whole order better performance than a large compression driver and is optimally loaded using a toroidal phase plug.

Wavefront series trapezoidal cabinets are fitted with MAN load-certified flying points and are designed to comply with the 12:1 safety factor specified by the German VBG70 standard when used with compatible 12:1 flying systems. One important advantage of the MAN flying system is that inter-cabinet connections place a minimal load on the cabinets and, being external, can be load certified and inspected independently.

1.2Specifications

Type: 3-way trapezoid, switchable active/passive

high-mid/high via rear panel switch (see Section 1.5)

Frequency response: 120Hz - 18kHz +/- 3dB LF limit: -10dB @ 100Hz Drivers: 1 x 12" (305mm) low-mid horn

1 x 6.5" (165mm) high-mid horn 1 x 1" (25mm) exit hf compression driver

Rated power: Low-mid 300W AES, 1200Wpk

High-mid (active/passive) 150W AES, 600Wpk High (active) 60W AES, 240Wpk

Sensitivity: Low-mid 106dB/W

High-mid 108dB/W High 107dB/W

Maximum SPL: 129dB continuous, 135dB peak

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Impedance: Low-mid 8 ohms nominal

High-mid 16 ohms nominal High 16 ohms nominal

Coverage (-6dB): 55º horizontal, 30º vertical Crossover: 750Hz, 3.5kHz Connectors: 2 x Neutrik NL8, 2 x EP8 Cabinet construction: Birch Ply Cabinet finish: Slate textured paint Protective grille: Perforated steel Grille finish: Grey paint Dimensions (incl wheels): (W) 562mm x (H) 799mm x (D) 925mm

(W) 22.1ins x (H) 31.5ins x (D) 36.4ins

Flown weight: 69kg (152lbs). Lid 4kg (9lb) extra

Before rigging, note colour coding! W8C has 2 black points per side

W8CS has 1 black point per side

W8CT has 2 orange points per side W8CM has 1 orange point per side

1.3 Pin-outs and cabling

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W8C

Connector type W8C mode EP8 NL8 W8C Active* W8C Passive*

1 -1 Low Mid - Low Mid 2 +1 Low Mid + Low Mid + 3 -2 High Mid - High Mid/High 4 +2 High Mid + High Mid/High + 5 -3 High - n/c 6 +3 High + n/c 7 -4 n/c n/c 8 +4 n/c n/c

(*see Section 1.5 for details of the connector panel Active/Passive switch

1.3.1 Cable and panel connector part numbers

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Please note the following part numbers when ordering loudspeaker connectors to make up cables and patch panels

Neutrik NL connectors NL8FC 8 pole cable (female)

NL8MPR 8 pole panel (male) NL8MM 8 pole inline coupler (male-male)

Cannon EP connectors EP8-11 8 pin cable female

EP8-12 8 pin cable male EP8-13 8 pin panel mount female EP8-14 8 pin panel mount male

Connectors should be kept in good, clean, uncorroded condition to ensure full, undistorted loudspeaker performance. Corroded or damaged pins and sockets can cause severe distortion or loss of signal.

1.3.2 Recommended loudspeaker cable

Cable run vs copper core cross sectional area

Single W8C Two W8C paralleled at the cluster.

Up to 50m 2.5mm² 6mm² (or 2 x 2.5mm² cores in parallel) Up to 100m 6mm² 10mm² (or 2 x 6mm² cores in parallel)

Q. Why the odd sizes? A. Loudspeaker cables are available in a limited range of standard copper core sizes -

ie. 1.5mm², 2.5mm², 4mm², 6mm², 10mm² and 35mm².

1.4 System patching

A good system patch should…

1) Be electrically safe - ie be put together by suitably qualified electrical technicians paying attention to possible sources of moisture, connector damage, cable damage, user and public safety.

2) Enable the system to provide the required sound quality, coverage and level

without feedback and without stressing its mechanical, electrical or

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electro-acoustic components.

3) Be divided into easily understood sections (eg Main, midfield, downfill etc) and clearly labelled so that adjustments may be made quickly and efficiently.

The schematic above shows a simple system using a Martin Audio DX1 Loudspeaker Management System configured as a 2 x 3way crossover controlling W8Cs switched for passive high-mid/high sections and W8CS subwoofers.

See the Section 1.5 for further DX1 information and Section 2 of this applications guide for a more complex example.

1.4.1 Cluster sub-sections

When designing a large sound system it is worth spending a little time working out a sensible cluster patch to optimise audience coverage.

The following example is a 4 wide, 4 deep W8C classical music centre cluster divided into farfield, midfield, nearfield and downfill horizontal rows and inner and outer vertical columns. The active (3-way) W8Cs may be patched in pairs for symmetrical control.

Recommended W8C pairs:

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Inner Farfield Outer Farfield Inner Midfield Outer Midfield Inner Nearfield Outer Nearfield Inner Downfield Outer Downfill

Controller channel allocations

The whole cluster may be controlled from just ½ a Martin Audio DX1 controller set up for 3-way operation. See Section 1.5 for further DX1 information.

Power amplifier channel allocations

There are 8 pairs of W8Cs each requiring high, high-mid & low-mid power amplifier channels.

8 pairs at 3 bands per pair = 24 amplifier channels required

= 12 x 2ch amplifiers per cluster.

2ch power amplifier allocations:

Farfield inner & outer high Farfield inner & outer himid Farfield inner & outer lomid Midfield inner & outer high Midfield inner & outer himid Midfield inner & outer lomid Nearfield inner & outer high Nearfield inner & outer himid Nearfield inner & outer lomid Downfill inner & outer high Downfill inner & outer himid Downfill inner & outer lomid

Initial inner level settings

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Initial inner level settings can be calculated for each row as follows:

The farfield inner power amplifier channels are the reference...

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Initial outer level settings

Similarly, initial outer level settings can be calculated for each row as follows:

Again, the farfield inner amplifier setting (0dB) is used as a reference...

In a fairly small, wide, fan-shaped venue with heavily raked seating, we may require the following amplifier channel settings:

The attenuation rate shown here is 2dB per cluster row. The actual rate of vertical

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attenuation will depend on the cluster height which in turn will depend on the rake of the seats. High clusters are further from the audience at the front and require less nearfield & downfill attenuation. The lower the cluster, the greater the required attenuation rate.

Again, the vertical layout is...

In a narrower venue, we may require the outer sections to be attenuated a little, particularly in the farfield section, as follows:

1.5 DX1 Loudspeaker Management System

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Martin Audio can provide factory set configuration cards for a variety of off-the-shelf crossover systems (contact your dealer or Martin Audio Ltd for further information) but the Martin Audio DX1 Loudspeaker Management System is strongly recommended for all new Wavefront system designs.

The Martin Audio DX1 is a very high performance DSP-based controller and provides crossover, protection, delay and alignment functions. As a Martin Audio product, the DX1 is kept up-to-date with preset crossover and limiter functions suitable for a wide range of system configurations and power amplifiers.

DX1 Factory Preset Examples

W8C Rear panel Active/Passive switch

Please note that the W8C rear connector panel is equipped with an Active/Passive switch.

Active mode (DX1 factory presets 21, 23 or 25)

In Active mode each driver (low-mid, high-mid & high) is driven by its own power amplifier channel. These power amplifier channels are sourced from the appropriate DX1 output to ensure optimal crossover and limiter alignment.

The advantages of active mode are:

Ø Smoother high-mid/high amplitude and phase response Ø Smoother high-mid/high vertical polar response Ø Improved high-mid/high amplifier headroom

Ø Improved high-mid/high limiter action

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Three Martin Audio MA2.8 power amplifiers will drive four W8Cs (assuming W8Cs driven in pairs).

Passive Mode (DX1 factory presets 20 & 22)

In Passive mode the high-mid and high drivers share a power amplifier channel via a passive high-mid/high crossover network built into the loudspeaker cabinet. This mode offers a slightly reduced performance but requires only two power amplifier channels per 3-way W8C system.

Two MA2.8s will drive four W8Cs (assuming W8Cs driven in pairs).

The following shows the DX1 with programme 20 selected. This caters for a stereo set-up comprising left and right W8Cs in Passive mode plus separate left and right WSX subwoofers:

DX1 factory preset 20 (2 x 3 way configuration)

Stereo WSX+W8C (passive high-mid/high) system

Custom DX1 set-ups

Experienced users may create custom DX1 set-ups, for example…

5 way configuration

e.g. W8C (active high-mid/high) system with flown W8CS’ (low 15) used as mid-

bass bins augmented by stacked WSXs (low 18).

See Section 2.4 for a full system example.

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1.5.1DX1 specifications

Inputs 2 electronically balanced. >10k ohms CMRR >65dB 50Hz - 10kHz Outputs 6 electronically balanced. <60 ohms Min. Load 600 ohm Max. Level +20dBm into 600 ohm load Frequency Resp. ±0.5dB 20Hz - 20kHz Dynamic Range >110dB 20Hz -20kHz. Unwtd Distortion <0.02% @ 1kHz, +18dBm Maximum Delay 650mS. (Increment 2.6uS) Output gain adjustable +15dB to -40dB in 0.1dB steps and mute Input gain adjustable +6dB to -40dB in 0.1dB steps

Parametric Equalisation Filters 5 Sections per output

Filter gain +15dB to -30dB in 0.1dB step Centre frequency 0Hz - 20kHz, 1/36 octave steps (368 positions) Filter Q / BW 0.4 to 128 / 2.5 to 0.008 (Sections switched to shelving response) Low frequency 20Hz - 1kHz High frequency 1kHz - 20kHz Shelf gains ±15dB in 0.1dB steps

Crossover (high-pass and low-pass) filters Filters 1 of each per output

Frequency (HPF) 10Hz - 16kHz, 1/36 octave steps Frequency (LPF) 60Hz - 22kHz, 1/36 octave steps Response Bessel / Butterworth 12/18/24dB per octave

Linkwitz-Riley 24dB per octave

Limiters Threshold +22dBu to -10dBu

Attack time 0.3 to 90 milliseconds Release time 4, 8, 16 or 32 times the attack time

Power required 60 to 250V ±15% @ 50/60Hz. < 20 watts Weight 3.5kg Net (4.8kg Shipping) Size 44 (1U) x 482 x 300mm excluding connectors

1.5.2 DX1 Output Gain and Limiter settings for W8Cs

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Standardising on one good model of power amplifier (preferably the Martin Audio

MA2.8) and correctly set-up controller (preferably the Martin Audio DX1) will

provide the most dynamic system performance and protection whilst simplifying design and reducing spares inventories.

Gain settings

The following DX1 output gain settings will enable full system performance to be obtained whilst keeping the console and drive system noise floors inaudible and avoiding amplifier slew-rate limiting:

W8C - assuming 300Wcont - 600Wpk into 8ΩΩ power amplifiers: Best-fit Initial DX1

Amplifier Amplifier Amplifier Output GAIN Example Sensitivity Gain LomidHimid High

dBu Vrms dB dB dB dB

Martin MA2.8* (38dB) -2 0.62 38 -9 -9 -7

Crest CA9 (x68) -1 0.69 37 -8 -8 -6

Crown MA1202 (0.775v) 0 0.77 36 -7 -7 -5

+1 0.87 35 -6 -6 -4

QSC PL224 +2 0.98 34 -5 -5 -3

+3 1.09 33 -4 -4 -2

Martin MA2.8* (32dB) +4 1.23 32 -3 -3 -1

Crest 4801 (x40) +4 1.23 32 -3 -3 -1

Crown K1 (1.4v) +4 1.23 32 -3 -3 -1

QSC PL218/218A (32dB) +4 1.23 32 -3 -3 -1

QSC PL224A (32dB) +4 1.23 32 -3 -3 -1

Crown MA1202 (1.4v) +5 1.38 31 -2 -2 0

+6 1.55 30 -1 -1 +1

+7 1.73 29 0 0 +2

+8 1.95 28 +1 +1 +3

+9 2.18 27 +2 +2 +4

Crown MA1202 (26dB) +10 2.45 26 +3 +3 +5

Crown K1 (26dB) +10 2.45 26 +3 +3 +5

QSC PL218A (26dB) +10 2.45 26 +3 +3 +5

QSC PL224A (26dB) +10 2.45 26 +3 +3 +5

* Set Martin Audio MA2.8 rear MLS switch to -2dB to match peak output of unregulated power amplifiers.

Cluster balance (eg farfield-to-nearfield or inner-to-outer) should be adjusted at the power amplifier controls to maintain limiter tracking. See Section 1.7.

Balancing the system using gain controls in the signal path before the power

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amplifiers will cause the higher signal level upper row of a big cluster to start limiting before the lower signal levels downfills causing tonal changes at the mix position.

Limiter settings

The Rated Power specifications in Section 1.2 show that the maximum allowable power dissipation depends on the driver/s being driven. This is because big low and low-mid drivers are capable of dissipating more heat than smaller high-mid and high drivers.

Normal music and speech signals, however, are a combination of relatively low general power levels with a multiplicity of short term transients. These short term transients do not significantly heat the driver voice coils so it is quite permissible to use the same 250-300W into 8Ω (500-600W into 4Ω) power amplifiers for all sections of the W8C, W8CT and W8CM as long as they are sourced by a correctly set

controller.

When choosing power amplifiers, do not be tempted to exceed the 250-300W into 8Ω (500-600W into 4Ω ) power rating unless the amplifier's power rails are well regulated (see Section 1.6) - even with properly set controllers in place.

Although Martin Audio drivers are mechanically designed to survive normal road use and the occasional operator error, over-powered or bridged amplifiers can cause overexcursions that stress and age drivers. The best way to get the clean, relaxed sound of an overpowered amplifier is to choose an amplifier with plenty of current reserve - ie an amplifier with good 2Ω specification - and avoid running more than two cabinets in parallel.

To ensure transparent limiter operation without obvious distortion or pumping, the DX1 limiter attack and release times are factory preset to be inversely proportional to each band's high pass frequency as follows:

High pass filter range Attack time Release time

>31Hz 45mS 720mS 31Hz - 63Hz 16mS 256mS 63Hz - 125Hz 8mS 128mS 125Hz - 250Hz 4mS 64mS 250Hz - 500Hz 2mS 32mS 500Hz - 1KHz 1mS 16mS 1KHz - 2KHz 0.5mS 8mS 2KHz - 22KHz 0.3mS 4mS

These attack times will allow the power amplifiers to clip momentarily but not for

long enough to be obvious to listeners or cause driver overheating. It is quite normal

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to see amplifier clip indicators on the odd programme peak but continuous clipping would indicate a cable short circuit, wrong controller settings, excessive power amplifier gain or low mains voltage.

The following DX1 output limiter settings will avoid voice coil overheating and minimise amplifier clipping for high quality, trouble free operation.

W8C - assuming 300Wcont - 600Wpk into 8ΩΩ power amplifiers: Best-fit Recommended

Amplifier Amplifier Amplifier DX1 LIMITER Example Sensitivity Gain LomidHimid High

dBu Vrms dB dBu dBu dBu

Martin MA2.8* (38dB) -2 0.62 38 -3 -6 -9

Crest CA9 (x68) -1 0.69 37 -2 -5 -8

Crown MA1202 (0.775v) 0 0.77 36 -1 -4 -7

+1 0.87 35 0 -3 -6

QSC PL224 +2 0.98 34 +1 -2 -5

+3 1.09 33 +2 -1 -4

Martin MA2.8* (32dB) +4 1.23 32 +3 0 -3

Crest 4801 (x40) +4 1.23 32 +3 0 -3

Crown K1 (1.4v) +4 1.23 32 +3 0 -3

QSC PL218/218A (32dB) +4 1.23 32 +3 0 -3

QSC PL224A (32dB) +4 1.23 32 +3 0 -3

Crown MA1202 (1.4v) +5 1.38 31 +4 +1 -2

+6 1.55 30 +5 +2 -1

+7 1.73 29 +6 +3 0

+8 1.95 28 +7 +4 +1

+9 2.18 27 +8 +5 +2

Crown MA1202 (26dB) +10 2.45 26 +9 +6 +3

Crown K1 (26dB) +10 2.45 26 +9 +6 +3

QSC PL218A (26dB) +10 2.45 26 +9 +6 +3

QSC PL224A (26dB) +10 2.45 26 +9 +6 +3

* Set Martin Audio MA2.8 rear MLS switch to -2dB to match peak output of unregulated power amplifiers.

Use lower limiter settings (or more loudspeakers!) if your power amplifiers indicate

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clipping on more than just the odd peak. Excessive clipping may also be caused by cable faults or an inadequate mains supply. See Section 1.6

The DX1 may be user-programmed to many more touring and fixed installation configurations based on its 2 input + sum, 6 output matrix. This operation is best completed by an audio technician who is familiar with DSP-based pro-audio.

(See separate DX1 Speaker Management System Operating User's Guide for details)

1.6Power amplifier recommendations

Wavefront Compact Series loudspeaker systems have been designed and manufactured for very high performance and arrayability. The systems are very easy to use - particularly if power amplifier racks and controller settings are standardised within a system.

Power capability

W8Cs will provide full performance when driven by professional power amplifiers capable of delivering undistorted output power into a range of loads as follows:

W8C

250-300W(AES) into 8 ohms, 500-600W(AES) into 4 ohms and 1,000-1,200W(AES) into 2 ohms.

Please note:

Amplifiers with inadequate headroom before clipping may age high frequency components due to excessive signal density.

Amplifiers with excessive output may damage voice-coils or age driver suspensions due to excessive heat dissipation and excursion.

A note about power amplifier output specifications

Most power amplifier manufacturers keep their costs down by using unregulated supply rails which sag under load. To allow for this sag, manufacturers set their rails high so that they still meet their quoted output into specified loads. These high rail voltages allow such power amplifiers to provide outputs 1.5 - 2 times their quoted power for short-term bursts. Martin Audio products will withstand this potential doubling of instantaneous power - with suitably set controller limiters - but further, long-term increases caused by oversized amplifiers should be avoided.

Martin Audio MA Series Power Amplifiers

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Martin Audio MA Series amplifiers have regulated rails so it is quite permissible to use slightly overpowered models - with suitably set controller limiters - without risking uncontrolled power bursts. The MA series power amplifiers’ regulated power rails also ensure maximum performance under the real-world concert conditions of less-than-optimum mains supplies and parallel cabinets. See Section 1.6.1.

Most non-Martin power amplifiers’ 4 ohm performance figures are specified assuming very well regulated bench supplies but fail to reach these specifications under touring conditions. These amplifiers can be a totally false economy as they cannot drive parallel cabinets without a very audible loss of headroom and quality.

Amplifier load tolerance

An efficient loudspeaker in live concert conditions can act as a surprisingly dynamic and complex load. Most modern touring power amplifiers claim 2 ohm capabilities but make sure your amplifier is also capable of driving reactive (ie inductive or capacitive) loads without prematurely clipping or developing output stage crossover distortion.

Mains safety!

A fully qualified technican should check mains safety and phase voltage before the system is patched.

Power reserve

Power amplifier specifications are usually based on bench measurements made using stable, high current mains supplies and well defined loads. Amplifiers sound best when they have plenty of current in reserve for musical peaks.

1) Try to ensure that the mains supply stays within the amplifier manufacturer’s specified range from no load to maximum load. An electrical technician should check the mains supply vs demand using an accurate rms voltage meter.

2) If unfamiliar generators are being used the electrical technician should check the mains waveform (using a portable ’scope-meter) to make sure that it is sinusoidal and not crawling with spikes or interference.

3) Avoid driving too many W8Cs in parallel. I would suggest no more than two so that the amplifier’s 2Ω spec is kept in reserve for musical peaks.

4) Avoid using power amplifiers in bridged mode. Most commercial power amplifiers are optimised for 2-channel operation. It is usually better to use the appropriate amplifier in 2-channel mode that to use an inadequate amplifier in bridged mode.

Gain or level settings

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Gain switches

If you are lucky enough to have amplifiers with user gain switches, set them all to identical positions. A voltage gain in the range 23-33dB will provide a good balance of system headroom and noise (assuming professional audio equipment is in use FOH).

Level controls

The front panel level controls should be turned down (fully counter clockwise) until FOH-to-Amp rack lines have been checked and controllers have been set to suit the power amplifiers to be used (see Section 1.5.2). Music should be used to check that controllers are receiving and sending the appropriate signal bands and then each power amplifier level control advanced in sequence to check system operation and patching.

Assuming that controller output levels and limiters have been set as tabulated in

Section 1.5.2, power amplifier level controls should be set to full (fully clockwise) for

loudspeaker sections requiring the strongest drive. Amplifiers driving nearer-field sections within the same cluster may be backed off as required for smooth coverage. This process will ensure that the cluster coverage remains balanced during limiting.

Rack mounting

1.6.1 Martin Audio MA2.8 Overview

Features

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Ø Switch mode power supply Ø Superior sonic performance Ø Light weight Ø Advanced protection circuits Ø Efficient copper cooling system Ø Minimum load switches (MLStm)

The MA2.8 power amplifier has been designed to combine reliability and high power output with sonic excellence. Utilising an advanced switch mode power supply, the MA2.8 yields a very high power-to-weight ratio in a lightweight, 2U package.

See MA2.8 Power Amplifier User's Guide for detailed operating instructions.

Cooling System

The Martin Audio MA2.8 amplifier runs very cool due to a special patented copper cooling system. The amplifier’s bi-polar output devices are mounted directly onto a copper heat sink (copper conducts heat twice as efficiently as aluminium) and maximum heat dissipation is achieved by turbulent airflow over the heatsink’s geometric fins.

The MA2.8 amplifier features two proportional speed cooling fans which take in air from the front of the amplifier and exhaust from the rear. A horizontal pressure chamber between the heatsink and the cooling fans ensures that there is little difference in the operating temperatures of each output device. In contrast, a conventional tunnel design can result in a temperature variance of up to 40° between output devices.

Switch Mode Power Supply

The MA2.8’s switch mode power supply (SMPS) is the modern solution to the problems of size and weight. Switch mode power supplies are not new - they are found in computers and televisions. However, the demands of high power audio are very different to these applications. The MA2.8 overcomes the size and weight constraints of conventional power supplies whilst at the same time avoiding the pitfalls of typical switch mode designs.

The low output impedance of the SMPS means that rail voltages do not sag under heavy load conditions. Additionally, the rail capacitors are being recharged at a much faster rate than those in a conventional power supply. The result is an exceptional fast transient low frequency performance at all power levels. Efficiency is also maximised. With much smaller transformers than a conventional supply, there is much less loss due to transformer resistance and much less power wasted as heat in the power supply.

The power amplifier will produce the same power output, even if the AC line voltage

drops by 20%.

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Minimum Load Switches (MLS™)

Because the SMPS is regulated, the maximum power available for the output stages can be adjusted without increased heat dissipation or efficiency loss. This allows the user to match the output power with the loudspeaker impedance.

Protection

The MA2.8 amplifier has many advanced protection features that will protect both the amplifier and the speakers connected to it, under fault conditions. All protection circuits are independent and inaudible in normal use.

Clip Limiters

Clip limiters prevent dangerous clipped signals reaching the speaker. They work by monitoring the output to check for signals not present at the input i.e.distortion. If distortion exceeds 1% on an output, the limiter will reduce the input signal proportionally.

Thermal Protection

Thermal Protection circuitry prevents the amplifier from running at an unsafe temperature by muting the input signal when the internal temperature rises above 90°C.

Short Circuit Protection

The MA2.8 amplifier is completely short circuit protected. The protection circuits permit very high peak currents, but maintain the output devices within their safe operating area.

Mains Voltage Protection

This operates if the mains voltage falls outside its permitted operating range. If this occurs, the power supply will shut down until the correct mains voltage is restored.

DC and VHF Protection

Both DC voltages and high power VHF signals can cause damage to loudspeakers. The MA2.8 amplifier incorporates protection circuits which are activated when damaging DC voltages or VHF signals are present at the outputs.

MA2.8 Specifications

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Input Impedance 20kohms (balanced) 10kohms single ended Gain select switch 38dB (I/P sens 0.775V), 32dB (I/P sens 1.55V) CMRR at 1kHz >50dB Output impedance at 1kHz 0.06 ohms Power Bandwidth 10Hz - 20kHz Slew rate 20V/us Hum/Noise <-105dB Channel Separation 1Khz > 90dB

10Khz > 80dB

Mains Operating Voltage 120 - 270 (minimum start voltage 190)

full output power maintained 180 - 280V. Optional (65 - 135V) operation.

Protection DC, High temperature, Turn on, VHF,

Over and under voltage, Clip limiters. Short

circuit. Distortion THD 20Hz - 20kHz and 1W – 1000W THD at 1kHz and 1100W DIM 30 at 500W CCIF (13 and 14 kHz) at 500W SMPTE (60Hz and 7kHz) at 500W Power Matrix

LOAD CONFIGURATION 16 ohms Stereo (2 channel) 8 ohms Stereo (2 channel) 4 ohms Stereo (2 channel)

2 ohms Stereo (2 channel)

16 ohms Bridged mono 8 ohms Bridged mono 4 ohms Bridged mono

4 ohms 0.08%

4 ohms 0.03%

4 ohms 0.02%

4 ohms 0.03%

4 ohms 0.08%

MLS SWITCH SETTING

(-5dB) (-4dB) (-2dB) (0dB)

160W 180W 340W 520W

300W 350W 650W 1100W

570W 680W 1100W 1400W

1900W[2]

1040W 1200W 1200W 1400W[1]

1400W[2] 2900W[2]

600W 700W 1300W 2000W

1200W 1400W 2200W 2800W

2100W 2400W 2400W 2800W[1]

[1] = Component tolerance dependent [2] = Continuous power, one channel driven or peak power both channels driven. Thermal protection may occur at high continuous power. Power in watts (EIA 1kHz, 1% THD) Weight 10kg (22lbs) Dimensions (W) 483mm x (H) 88mm x (D) 347mm

(W) 19ins x (H) 3.5ins x (D) 13.7ins

1.7 General operational summary

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1) Always use the same model system controller and power amplifier for a

particular Wavefront product. This avoids confusion caused by different controller topologies and power amplifiers voltage gains.

2) It is common practice to use mixing console matrix outputs as loudspeaker

section controls. Whilst this is fine for creating a bass submix which can easily be judged from the mix position, it can be fraught with danger if used for audience sections which may only be audible in very specific areas. Trim these remote sections, during listening tests with a colleague via walkie talkie, using the relevant controller input gains. If the console matrix cannot be avoided, try to pre-calibrate its output levels controls to their 0dB (nominal) position initially. These settings will be easier to get back to and will avoid embarrassing level setting mistakes during the show - particularly if the system is being used by guest operators who may not be familiar with your particular matrix allocations.

3) And again, trim levels within clusters (eg farfield vs midfield or inners vs

outers) using the amplifier level controls to ensure limiter tracking.

1.8 Arraying & placement

Simple stacked systems

Single W8C

A single Wavefront W8C cabinet will cover 55º horizontally x 30º vertically and may be used as a stand-alone system for a variety of light music and voice applications including commercial presentations.

A W8C may be combined with a W8CS compact subwoofer or a WSX horn-loaded subwoofer to extend its low frequency performance.

Single W8C on W8CS subwoofer

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This very compact stack may be used for as one side of a main system for a folk band concert in a small venue, one corner of a small dance floor system, stage side fills, stage drum fills, front fills etc.

SAFETY REMINDER!

Stacks should always be safety strapped to allow for high winds, over-exuberant artists, crowd indicipline, scenery movements etc.

Wide coverage, broadband stack

Although a single Wavefront W8C’s horizontal coverage is 55º at high frequencies, the system has been designed to integrate well with smaller splays for practical output summing. A splay of 40º between axes (260mm between cabinet front corners) provides very smooth 95º horizontal coverage with little increase in mid-band output level whilst a smaller splay angle (typically 30º) can boost the forward output level by 2-3dB.

2-wide W8C/W8CS stack

This very compact stack may be used as one side of a small venue main system, one corner of a dance system, high power stage side fills, drum fills, centre fills etc.

Flown systems overview

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Flown clusters are recommended for very high power music systems covering large venues to ensure adequate coverage without excessive levels at the front of the venue.

Wavefront series products are fitted with MAN load-certified flying points and are designed to comply with the 12:1 safety factor specified by the German VBG70 standard when used with compatible 12:1 flying systems.

MAN Transformer or Installer/Tourer flying systems allow columns of loudspeakers to be assembled by attaching individual loudspeakers to vertically daisy-chained Drings using keyhole cabinet fittings - hence the tendency to base flown designs in this applications guide on multiple columns. The beauty of the MAN system is that each cabinet in a system supports only its own weight.

Each pair of vertical chains is attached to a single-width, centrally pivoted sub-bar which, in turn, is attached to a two-way, centrally pivoted flying bar so that the system “finds its own level”, if accidentally hoisted asymmetrically, avoiding undue stresses and strains.

Vertical columns are splayed by tensioning a rachet strap threaded through the subbar and all of the cabinet back plates.

Cabinets may be fitted with rear hinge back plates to allow removable hinges to be

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slotted in place. These hinge assemblies provide a more rigid rear cabinet alignment.

For further information please refer to the Martin Audio Wavefront 8 Flying System User Guide.

Rigging Schools!

Rigging should not be undertaken by untrained or unqualified personnel. Suitable rigging training sessions may be arranged by calling Martin Audio Ltd on

+44 (0)1494 535312.

Important note on flown systems examples

Wavefront cluster examples are included in this manual to illustrate recommended loudspeaker combinations and splay angles only. Note that very large clusters particularly those including Wavefront Longthrow elements - may need to be flown in multiple layers to maintain the 12:1 safety factor of the standard Martin Audio Wavefront 8 Flying System.

SAFETY NOTE!

Two female "keyhole" stud plates are fitted to each side of Wavefront cabinets to allow cabinets to be flown up-side-down for certain applications. The upper keyhole is the only one ever used - whatever the configuration.

OK No, No, No!!!

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i) NEVER suspend one cabinet from the lower flying point of the cabinet above. ii) NEVER suspend standard cabinets horizontally.

Two Wavefront Compact W8Cs correctly rigged using upper key-holes only

1.9 Coverage calculations

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Single W8C column

Here is an example of a 1-wide, 3 deep column of Wavefront W8Cs.

The horizontal coverage is, of course, that of a single W8C ie 55º.

The vertical coverage of a W8C cluster can be calculated as follows:

Vertical coverage of a W8C = the vertical coverage of a single W8C (30º) + the

sum of all the vertical splay angles

For a 3-deep W8C cluster with 15º vertical splay angles = 30º+15º+15º = 60º For a 3-deep W8C cluster with 20º vertical splay angles = 30º+20º+20º = 70º

Double W8C column

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Here is a 2 wide, 3 deep column of Wavefront W8Cs.

The vertical coverage can be calculated as follows:

For a 3-deep W8C cluster with 15º vertical splay angles = 30º+15º+15º = 60º For a 3-deep W8C cluster with 20º vertical splay angles = 30º +20º+20º = 70º

The horizontal coverage can be calculated as follows:

For a 2-wide W8C cluster with 30º horizontal splay angles = 55º+30º = 85º For a 2-wide W8C cluster with 40º horizontal splay angles = 55º+40º = 95º

Wide coverage cluster

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4 or 6 wide, 4 deep W8C clusters may be rigged for very wide coverage. Coverage may be calculated as follows:

6 wide cluster

The horizontal coverage now extends to:

55º+30º+30º+30º+30º+30º = 205º for 30º horizontal splays 55º+40º+40º+40º+40º+40º = 255º for 40º horizontal splays

and the vertical coverage extends to:

30º+15º+15º+15º = 75º for 15º vertical splays 30º+20º+20º+20º = 90º for 20º vertical splays

6 wide, 4 deep plan view

Circular cluster

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Two 6-wide, 4 deep W8C clusters with 30º horizontal splay angles and 20º vertical splay angles may be flown back-to-back to provide full 360º horizontal x 90º vertical coverage for ice shows, for example.

Column View

Note that the 90º coverage allows foldback to be provided to the ice-dancers. The centre hole may be filled by flying a smaller cabinet underneath the main cluster.

1.10W8Cs as front fills

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Wavefront W8Cs may be used as stage apron fills for high power rock concerts. When carefully placed on radii converging at the centre downstage (lead vocal) area and sychronised with the main PA downfills, these apron fills don't just balance the subwoofers. They can focus vocals and add a detailed quality that can be beneficial right out to the mix position.

If the apron fill loudpeaker signal is delayed by the difference between the downfill propagation time and the apron fill propagation time and attenuated by the ratio of those propagation times, the sound will appear to come from an area in between the two systems for the listener shown.

Apron fill delay line setting = t downfill - t apron fill

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Apron fill gain setting wrt downfill gain = 20log10(t downfill ÷ t apron fill) dB

1.11 W8Cs as side clusters

A Wavefront Longthrow (See Section 2) centre cluster may be used with W8C downfills for efficient operatic and orchestral amplification. Velodrome side seats can be some distance away (typically across a wide cycle track) so fairly powerful side clusters may be required for good projection and intelligibility.

W8Cs are ideal for this application as they blend in sonically without off-axis lobing and stage mic colouration.

Deep orchestral stage continues this way ñ

To avoid abrupt changes in timbre between the side and centre cluster, the side downstage W8C axis should be aimed at the seating where the centre cluster is just beginning to lack very high frequencies.

Controller output levels and delays should be adjusted so that the side and centre clusters are at the same level and sychronised in the same area.

1.12 W8Cs in distributed (delay) systems

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Wavefront W8C Compacts make very good high power distributed systems or delay elements as they project sound smoothly and efficiently without local off-axis lobing.

For good overall coverage, delays are best driven in mono for most of the show although computer controlled matrix mixes may be considered for panning spot effects around the venue.

Flown radial delays

Flown distribution or delay loudspeakers should be placed on radii converging at the stage and staggered for smooth coverage.

Distributed flown loudspeaker plan (stage system not shown)

Delay times should be set for synchronisation with the next most powerful source. This would be the stage for the first row of delays (below left) or the previous row (below right) for farfield delays.

Synchronising flown central delays

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Synchronising flown outer delays

Ideally, the sound should be perceived as coming from the stage over the whole audience area - which means that all the delay loudspeakers should be aligned with the stage opening. In practice, sight line, follow spot and camera shot restrictions will affect placement for heavily raked seating areas and intelligent compromises will need to be made.

Delay systems should be thoroughly checked over a wide listening area to ensure that their level settings provide smooth coverage without hot spots. Delay times and levels should be finely adjusted to minimise multiple arrivals in seating areas where systems cannot be in line with the stage and more than one source can be heard.

Aiming delay tower loudspeakers

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Multiple delay tower loudspeakers should be tilted so that they aim towards head height at the next tower to mask off-axis tower leakage and to minimise multiple arrivals further out.

Synchronising multiple tower systems

(not to scale)

Small delay time errors are inevitable where delay towers are located in audience areas (eg on a football field) due to the three dimensional geometry involved.

Initially, controller delays should be adjusted for synchronisation along a line between staggered delay towers and then modified as necessary to minimise timing errors around each tower and over its main coverage area.

The Martin Experience

Wavefront Compact Series

Applications Guide

Section 2

Wavefront Longthrow

W8CT & W8CM

Line Array System

CONTENTS

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MARTIN AUDIO

LONDON

Section 2

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Wavefront Longthrow W8CT & W8CM Line Array System

Contents

2.1 Introduction

2.2 Specifications

2.3 Pin-outs and cabling

2.4 System patching

2.5 DX1 gain & limiter settings

2.6 Power amplifier recommendations

2.7 General system reminders

2.8 Coverage

2.9 Further examples

Section 2a

Climatic effects on sound propagation

2a.1 Introduction 2a.2 Wind effects 2a.3 Temperature effects 2a.4 Relative humidity effects

Wavefront Longthrow W8CT & W8CM

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Line Array System

2.1Introduction

The Martin Audio Wavefront Longthrow W8CT & W8CM Line Array System is a compact, light weight, very high power, multiple horn line array loudspeaker system in a trapezoidal cabinet sharing design concepts and footprints with the rest of the popular Martin Audio Wavefront Compact family.

Unlike other manufacturers who have been rushed into production to exploit the recently recognised benefit of line array systems, Martin Audio have manufactured modular line array systems for many years. The Martin Audio Wavefront Longthrow system benefits from this proven track record. It uses established components and stacked horn techniques to provide a sensible, arrayable horizontal performance compatible with the rest of the Wavefront family.

Although designed to be rigged in continuous columns for very long throw operation, Wavefront Longthrow elements may also be used within W8C clusters to provide spot coverage to distant balcony or corner seating.

The Wavefront Longthrow W8CT integrates three horn-loaded 6.5" high-mid drivers with six horn-loaded 1" high frequency compression drivers. Like the award-winning W8C high-mid system , the W8CT high-mid driver is optimally loaded using a toroidal phase plug to produce much lower distortion than a typical waveguide-loaded compression driver.

The Wavefront Longthrow W8CM comprises two horn-loaded 12" low-mid drivers to complement W8CT high-mid/high systems.

Wavefront Longthrow W8CTs and W8CMs are fitted with MAN load-certified flying points designed to comply with the 12:1 safety factor to the German VBG70 standard when used with compatible 12:1 flying systems.

2.2Specifications

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W8CT Type: Dedicated longthrow high-mid/high enclosure

Frequency response: 750Hz-18kHz +/- 3dB Drivers: 3 x 6.5" (165mm) high-mid horn

6 x 1" (25mm) exit hf compression driver Rated power: High-mid 450W AES, 1800W peak

High 360W AES, 1440W peak Sensitivity: High-mid 113dB

High 115dB Maximum SPL: High-mid: 139dB continuous, 145dB peak

High: 141dB continuous, 147dB peak Impedance: High-mid: 6 ohms nominal

High: 2 x 6 ohms nominal

Coverage (-6dB): 55º horizontal, Line vertical (see Section 2.8) Crossover: 750Hz, 3.5kHz Connectors: 2 x Neutrik NL8 Cabinet construction: Birch Ply Cabinet finish: Slate textured paint Protective grille: Perforated steel Grille finish: Grey paint Dimensions (incl wheels): (W) 562mm x (H) 799mm x (D) 925mm

(W) 22.1ins x (H) 31.5ins x (D) 36.4ins

Flown weight: 81kg (178lb). Lid 4kg (9lb) extra

W8CM Type: Dedicated longthrow low-mid enclosure

Frequency response: 120Hz-750Hz +/- 3dB LF limit: -10dB @ 80Hz Drivers: 2 x 12" (305mm) low-mid horn

Rated power: 600W AES, 2400 peak Sensitivity: 109dBspl/W Maximum SPL: 136dBspl continuous, 142dBspl peak Impedance: 4 ohms

Coverage (-6dB): 55º horizontal, Line vertical (see Section 2.8)

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Crossover: 120Hz, 750Hz Connectors: 2 x Neutrik NL8 Cabinet construction: Birch Ply Cabinet finish: Slate textured paint Protective grille: Perforated steel Grille finish: Grey paint Dimensions (incl wheels): (W) 562mm x (H) 799mm x (D) 925mm

(W) 22.1ins x (H) 31.5ins x (D) 36.4ins

Flown weight: 72kg (158lb). Lid 4kg (9lb) extra

Before rigging, note colour coding! W8C has 2 black points per side

W8CS has 1 black point per side

W8CT has 2 orange points per side W8CM has 1 orange point per side

2.3 Pin-outs and cabling

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W8CT & W8CM NL8 W8CT W8CM

-1 Link through Low Mid +1 Link through Low Mid +

-2 High Mid - Link through +2 High Mid + Link through

-3 High 1 - Link through +3 High 1 + Link through

-4 High 2 - Link through +4 High 2 + Link through

(See Section 1.3 for connector pin-out drawing)

2.3.1 Cable and panel connector part numbers

Please note the following part numbers when ordering loudspeaker connectors to make up cables and patch panels.

Neutrik NL connectors NL8FC 8 pole cable (female)

NL8MPR 8 pole panel (male) NL8MM 8 pole inline coupler (male-male)

Connectors should be kept in good, clean, uncorroded condition to ensure full, undistorted loudspeaker performance. Corroded or damaged pins and sockets can cause severe distortion or loss of signal.

2.3.2 Recommended loudspeaker cable

Note that a standard 8-core loudspeaker cable will drive through-linked pairs of W8CTs and W8CMs.

The following table gives suitable copper core specifications for common applications:

Cable run vs copper core cross sectional area

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One W8CT Two W8CTs in parallel or W8CT/CM or two W8CT/CM combination combinations in parallel

at the cluster.

Up to 50m 4mm² (or 2x 2.5mm²cores in parallel) 10mm² (or 2x 4mm²cores

in parallel)

Up to 100m 10mm² (or 2x 4mm²cores in parallel) Not recommended -

but use 2x 10mm² cores in parallel if you must.

Q. Why the odd sizes? A. Loudspeaker cables are available in a limited range of standard copper core sizes -

ie. 1.5mm², 2.5mm², 4mm², 6mm², 10mm² and 35mm².

2.4 System patching

A good system patch should:

1) Be electrically safe - ie be put together by suitably qualified electrical

technicians

2) Enable the system to provide the required sound quality, coverage and level

without feedback and without stressing its mechanical, electrical or electroacoustic components.

3) Be divided into easily understood sections (eg Main, midfield, downfill etc)

and clearly labelled so that adjustments may be made quickly and efficiently.

Although the last two points may seem insultingly obvious to users who are naturally well organised, they are very important. Each Longthrow section may be covering several thousand people and fairly minor mis-patches can have major consequences bearing in mind that outdoor events - particularly orchestral concerts - are often competing with noise from food and drink stand generators, over-flying aircraft, local traffic etc.

The above schematic shows a typical system incorporating a row of Wavefront

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Longthrow W8CT & W8CM elements with Wavefront Compact W8Cs and W8CS’ crossed over as flown mid-bass sections to augment floor stacked WSX subwoofers.

The system uses Martin Audio DX1 Loudspeaker Management Systems configured as 5-way crossovers. Martin Audio can provide factory set configuration cards for a variety of off-the-shelf crossover systems (contact your dealer or Martin Audio for further information) but, the Martin Audio DX1 Loudspeaker Management System is strongly recommended for all new Wavefront Longthrow system designs. See Section

1.5 for DX1 details.

For further notes on system patching, including cluster sub-section controller and

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amplifier allocations see Section 1.4.

2.5 DX1 gain & limiter settings

Standardising on one good model of power amplifier (preferably the Martin Audio

MA2.8) and correctly set-up controller (preferably the Martin Audio DX1) will

provide the most dynamic system performance and protection whilst simplifying design and reducing spares inventories.

The Martin Audio DX1 Loudspeaker Management System may be user-programmed for a wide range of touring configurations based on its 2 input + sum, 6 output matrix. This operation is best completed by an audio technician who is familiar with DSP based pro-audio equipment. (See Section 1.5 and DX1 Speaker Management System

User's Guide for further details)

Gain settings

The following initial DX1 output gain settings will enable full system performance to be obtained whilst keeping the console and drive system noise floors inaudible and avoiding amplifier slew-rate limiting:

W8CT & W8CM - assuming 600Wcont - 1200Wpk into 4ΩΩ power amplifiers: Best-fit Initial DX1

Amplifier Amplifier Amplifier Output GAIN Example Sensitivity Gain LomidHimidHigh

dBu VrmsdB dB dB dB

Martin MA2.8* (38dB) -2 0.62 38 -9 -9 -9

Crest CA9 (x68) -1 0.69 37 -8 -8 -8

Crown MA1202 (0.775v) 0 0.77 36 -7 -7 -7

+1 0.87 35 -6 -6 -6

QSC PL224 +2 0.98 34 -5 -5 -5

+3 1.09 33 -4 -4 -4

Martin MA2.8* (32dB) +4 1.23 32 -3 -3 -3

Crest 4801 (x40) +4 1.23 32 -3 -3 -3

Crown K1 (1.4v) +4 1.23 32 -3 -3 -3

QSC PL218/218A (32dB) +4 1.23 32 -3 -3 -3

QSC PL224A (32dB) +4 1.23 32 -3 -3 -3

Crown MA1202 (1.4v) +5 1.38 31 -2 -2 -2

+6 1.55 30 -1 -1 -1

+7 1.73 29 0 0 0

+8 1.95 28 +1 +1 +1

+9 2.18 27 +2 +2 +2

Crown MA1202 (26dB) +10 2.45 26 +3 +3 +3

Crown K1 (26dB) +10 2.45 26 +3 +3 +3

QSC PL218A (26dB) +10 2.45 26 +3 +3 +3

QSC PL224A (26dB) +10 2.45 26 +3 +3 +3

* Set MA2.8 rear MLS switch to -2dB.

Cluster balance (eg inner-to-outer) should be adjusted at the power amplifier

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controls to maintain limiter tracking. See Section 2.7.

Balancing the system using gain controls in the signal path before the power amplifiers is not recommended as it will cause the higher signal level upper rows of a big cluster to start limiting before the lower signal levels downfills causing tonal changes at the mix position.

Limiter settings

The Rated Power specifications in Section 2.2 show that the maximum allowable power dissipation depends on the driver/s being driven. This is because big low and low-mid drivers are capable of dissipating more heat than smaller mid-high and high drivers.

Normal music and speech signals, however, are a combination of relatively low general power levels with a multiplicity of short term transients. These short term transients do not significantly heat the driver voice coils so it is quite permissible to use the same 250-300W into 8Ω (500-600W into 4Ω) power amplifiers for all sections of the W8CT and W8CM as long as they are sourced by a correctly set

controller.

When choosing power amplifiers, do not be tempted to exceed the 250-300W into 8Ω (500-600W into 4Ω ) power rating unless the amplifier's power rails are well

regulated (see Section 2.6) - even with properly set controllers in place. Although Martin Audio drivers are mechanically designed to survive normal road use and the occasional operator error, overpowered or bridged amplifiers can cause overexcursions that stress and age drivers. The best way to get the clean, relaxed sound of an overpowered amplifier is to choose an amplifier with plenty of current reserve - ie an amplifier with good 2Ω specification - and avoid running more than two cabinets in parallel.

High pass filter range Attack time Release time

>31Hz 45mS 720mS 31Hz - 63Hz 16mS 256mS 63Hz - 125Hz 8mS 128mS 125Hz - 250Hz 4mS 64mS 250Hz - 500Hz 2mS 32mS 500Hz - 1KHz 1mS 16mS 1KHz - 2KHz 0.5mS 8mS 2KHz - 22KHz 0.3mS 4mS

These attack times allow the power amplifiers to clip momentarily - but not for long

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enough to be obvious to listeners or cause driver overheating. It is quite normal to see amplifier clip indicators on the odd programme peak but continuous clipping would indicate a cable short circuit, wrong controller settings, excessive power amplifier gain or low mains voltage.

The following DX1 output limiter settings will avoid voice coil overheating and minimise amplifier clipping for high quality, trouble free operation.

W8CT & W8CM - assuming 600Wcont - 1200Wpk into 4ΩΩ power amplifiers: Typical Recommended

Amplifier Amplifier Amplifier DX1 LIMITER Example Sensitivity Gain Settings

dBu VrmsdB LomidHimidHigh

dBu dBu dBu

Martin MA2.8* (38dB) -2 0.62 38 -3 -6 -9

Crest CA9 (x68) -1 0.69 37 -2 -5 -8

Crown MA1202 (0.775v) 0 0.77 36 -1 -4 -7

+1 0.87 35 0 -3 -6

QSC PL224 +2 0.98 34 +1 -2 -5

+3 1.09 33 +2 -1 -4

Martin MA2.8* (32dB) +4 1.23 32 +3 0 -3

Crest 4801 (x40) +4 1.23 32 +3 0 -3

Crown K1 (1.4v) +4 1.23 32 +3 0 -3

QSC PL218/218A (32dB) +4 1.23 32 +3 0 -3

QSC PL224A (32dB) +4 1.23 32 +3 0 -3

Crown MA1202 (1.4v) +5 1.38 31 +4 +1 -2

+6 1.55 30 +5 +2 -1

+7 1.73 29 +6 +3 0

+8 1.95 28 +7 +4 +1

+9 2.18 27 +8 +5 +2

Crown MA1202 (26dB) +10 2.45 26 +9 +6 +3

Crown K1 (26dB) +10 2.45 26 +9 +6 +3

QSC PL218A (26dB) +10 2.45 26 +9 +6 +3

QSC PL224A (26dB) +10 2.45 26 +9 +6 +3

* Set Martin Audio MA2.8 rear MLS switch to -2dB.

2.6Power amplifier recommendations

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Wavefront Longthrow loudspeakers have been designed and manufactured for very high performance over great distances. They are very easy - particularly if power amplifier racks and controllers are standardised within a system.

Power capability

W8CTs and W8CMs will provide full performance when driven by professional power amplifiers capable of delivering undistorted output power into a range of loads as follows:

W8CT & W8CM

250-300W(av) into 8 ohms, 500-600W(av) into 4 ohms and 1,000-1,200W(av) into 2 ohms.

Please note:

Amplifiers with inadequate headroom before clipping may age high frequency components due to excessive signal density.

Amplifiers with excessive output may damage voice-coils or age driver suspensions due to excessive heat dissipation and excursion.

A note about power amplifier output specifications

Martin Audio MA series power amplifiers have regulated rails so it is quite permissible to use slightly overpowered models - with suitably set controller limiters without risking uncontrolled power bursts. The MA series power amplifiers’ regulated power rails also ensure maximum performance under the real-world concert conditions of less-than-optimum mains supplies and low impedance loads.

See Section 1.6.1 for information on the Martin Audio MA2.8 power amplifier.

Amplifier load tolerance

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An efficient loudspeaker in live concert conditions can act as a surprisingly dynamic and complex load. Most modern touring power amplifiers claim 2 Ohm capabilities but make sure your amplifier is also capable of driving reactive (ie inductive or capacitive) loads without prematurely clipping or developing output stage crossover distortion.

Power Reserve

Most power amplifier specifications are based on bench measurements made using stable, high current mains supplies and well defined loads.

Amplifiers sound best when they have plenty of current in reserve for musical peaks.

General power amplifier reminders

1) Try to ensure that the mains supply stays within the amplifier manufacturer’s

specified range from no load to maximum load. An electrical technician should check the mains supply vs demand using an accurate true rms voltage meter.

2) If unfamiliar generators are being used the electrical technician should check

the mains waveform (using a portable ’scope-meter) to make sure that it is sinusoidal and not crawling with spikes or interference.

3) Avoid driving more than one W8CT high-mid or high section or one W8CM

cabinet per power amplifier channel. This will keep the power amplifier’s 2 ohm capability in reserve for musical peaks.

4) Avoid using power amplifiers in bridged mode. Most commercial power

amplifiers are optimised for 2-channel operation. It is usually better to use the appropriate amplifier in 2-channel mode than to use an inadequate amplifier in bridged mode.

Gain or level settings

Gain switches

Level controls

The front panel level controls should be turned down (fully counter clockwise) until FOH-to-Amp rack lines have been checked and controllers have been set to suit the power amplifiers to be used (see Section 2.5). Music should be used to check that controllers are receiving and sending the appropriate signal bands and then each

power amplifier level control advanced in sequence to check system operation and

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patching.

Assuming that controller output levels and limiters have been set as tabulated in

Section 2.5, power amplifier level controls should be set to full (fully clockwise) for

loudspeaker sections requiring the strongest drive. Amplifiers, driving nearer-field sections within the same cluster, may be backed off as required for smooth coverage. This process will ensure that the cluster coverage remains balanced during limiting.

Rack mounting

Always leave a 1U space between power amplifiers and controllers. Although most modern amplifiers don’t radiate significant fields it’s better to play safe and keep the system quiet. The spare space may prove useful when last minute controller additions are required for, say, extra audience fills. Rear supports are recommended. Check the manufacturer's application notes for details.

2.7General system reminders

1) Where possible, use the same model system controller and power amplifier for

a particular Wavefront product. This avoids confusion caused by different controller topologies or by power amplifiers with different voltage gains for the same output specs.

2) It is common practise to use mixing console matrix outputs as loudspeaker

section controls. Whilst this is fine for creating a bass submix which can easily be judged from the mix position, it can be fraught with danger if used for Longthrow loudspeaker sections which may only be audible by touring the site on a bicycle! Trim outfield sections during listening tests with a colleague via walkie talkie, using the relevant controller input gains.

If the console matrix is the only solution available, try to pre-calibrate the matrix output levels controls to their 0dB (nominal) position initially. These settings will be easier to get back to and will avoid embarrassing level setting mistakes during the show - particularly if the system is being used by guest operators who may not be familiar with your particular matrix allocations.

3) And again, trim levels within clusters (eg inners vs outers) using the amplifier

level controls to ensure limiter tracking.

2.8 Coverage

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W8CT and W8CMs are designed to be flown in vertical line arrays to provide a combination of W8C-compatible 55º horizontal coverage with tight vertical control.

The vertical coverage of a single W8CT is approximately 7.5º in the upper midrange. When dead-hung, as illustrated below, the vertical coverage narrows with increasing cluster height following the classic law for multi-element line arrays.

* = speed of sound (m/s).Varies with temp. (see Section 2a) Arcsin = "the angle whose sin is..."

(Note that Nd works out to be the total height of the column in meters)

Straight column gain and coverage

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The following table shows typical Longthrow high-mid/high gain (wrt a single Wavefront W8C) plus the mid and high frequency vertical coverage provided by various straight vertical line arrays.

W8CTs in high-mid/high gain vertical coverage (-6dB points)

(wrt single W8C) high-mid high

1 (single row) 9.5dB 7.42º 3.70º 2 (double row) 16dB 3.72º 1.86º 4 22dB 1.86º 0.93º 6 25dB 1.24º 0.62º 8 28dB 0.93º 0.46º 10 30dB 0.74º 0.37º

The above means that, for practical sound reinforcement uses, a long straight column's mid and high frequency coverage must be regarded as being cylindrical in nature. Low-mid vertical coverage will widen in the farfield depending on the height of the column but users should be guided by the following coverage shape to ensure consistent high frequency coverage.

Straight W8CT column mid/hf coverage = 55º (horizontal) x the column height

A long, straight Wavefront Longthrow column will cover vast flat outdoor areas if you aim the column axis towards the rear of the audience. Remarkable results can be obtained indoors using continuous columns running from stage level to the maximum seating height.

Unfortunately, continuous vertical columns are rarely visually acceptable -

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particularly where the audience wraps around a thrust stage and sight lines are critical. In such cases, shorter Longthrow columns may be flown in combination with Wavefront W8C midfields and downfills.

Martin Audio/M.A.N. Flying System overview

Flown clusters are recommended for very high power music systems covering large venues to ensure adequate coverage without excessive levels at the front of the venue.

Vertical splay angles are determined by intercabinet chain lengths whilst the overall column tilt is determined by the length of the chains between the upper cabinet and the sub-bar. Vertical columns are splayed by tensioning a rachet strap threaded through the sub-bar and all of the cabinet back plates. Cabinets may be fitted with rear hinge back plates to allow removable hinges to be slotted in place. These hinge assemblies provide a more rigid rear cabinet alignment.

For further information please refer to the Martin Audio Wavefront 8 Flying System User Guide.

IMPORTANT NOTES!

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Rigging should not be undertaken by untrained or unqualified personnel. Suitable rigging training sessions may be arranged by calling Martin Audio Ltd on +44 (0)1494 535312.

Flown systems examples

Safety reminder

Two female "keyhole" stud plates are fitted to each side of Wavefront W8C and W8CT cabinets to allow cabinets to be flown up-side-down for certain applications. The upper keyhole is the only one ever used - whatever the configuration.

OK No, No, No!!!

i) NEVER suspend one cabinet from the lower flying point of the cabinet above. ii) NEVER suspend standard cabinets horizontally.

2.9 Further examples

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Wavefront Longthrow columns may be horizontally arrayed for wide coverage:

(left & right clusters will be mirror image)

High-mid/high horizontal coverage would be

1/2 left W8CT + 30º + 30º + 1/2 right W8CT = one W8CT +30º + 30º = 55º + 60º = 115º.

2.9.1 Flying with W8CS’

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Wavefront Longthrow columns may be flown with Wavefront W8CS’ (Section 3). The W8CS’ may be configured as fullbass systems - to leave the floor free for camera tracks, for example - or as a mid-bass section to augment floor-stacked WSXs where a large, standing audience is expected forward of the mix position.

Reminder!

Splay angles are always quoted axis-to-axis - not between cabinet sides!

ie.

|‹ 0º ›|‹ 30º ›|‹ 0º ›|

As with W8Cs, the single-box horizontal coverage is 55º. Horizontal splay angles of 25-35º between axes will provide coherent polar response summations resulting in smooth coverage with consistent tonal characteristics.

2.9.2 Flying with W8Cs

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Wavefront Longthrow columns may be flown with Wavefront Compact W8C midfield and downfill sections.

The following example shows a wide coverage Longthrow system with W8C midfield and downfill sections. Note that a double (vertically tightpacked) row of W8Cs has been flown as the midfield section. Vertically tightpacking these W8Cs extends their forward throw to help smooth the transition from Wavefront Longthrow to Wavefront W8C. The vertical splay angle between the main Longthrow column and the double W8C midfield section is kept small to avoid vertical coverage gaps.

20 20

8 8 8 8 8 8

20 20 20 20 20

15 15 15

Note that the Longthrow system's output is considerably greater than the Compact's for the same input voltage so some level tailoring tends to be required to provide smooth coverage with distance.

FAQ: Why do you use powerful Longthrow and tight-packed sections and then

turn them down?

A: The tight vertical coverage of the Longthrow and tight-pack sections allows

us to concentrate high quality sound onto the audience without exciting roof resonances. They help maintain excellent direct-to-reverb ratios.

A typical arena gain set-up may be as follows:

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Main Longthrow section -12dB to -6dB Double W8C midfield section -6dB to 0dB W8C downfills -4dB to 0dB

2.9.3 Adding Longthrow elements to W8C/W8CS clusters

Wavefront Longthrow elements may be added to conventional W8C/CS clusters for larger venues, to improve overall sound projection to, for example, upper rear seats.

Note that when just a few Wavefront Longthrow elements are used to supplement a large W8C system, high-mid/high W8CTs may be used without low-mid W8CMs as low-mid energy is provided by adjacent W8C low-mid sections.

= W8CT, = W8C, = W8CS

8 8 8 8

20 20 20 20

15 15

A simplified maximum horizontal coverage calculation is:

27.5º (left ½ W8C/W8CT) + 15º + 15º + 27.5º (right ½ W8C/W8CT) = 85º

A simplified maximum vertical coverage calculation is:

3.75º (top ½ W8CT) + 8º + 20º + 20º + 15º (bottom ½ W8C) = 66.75º

Climatic effects on sound propagation

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2a.1Introduction

When working in large venues or outdoors we should always remember that sound propagates through air and is affected by air temperature, humidity and wind.

The most audible of these effects is wind as it can vary dramatically in less than a second causing rapidly swept filter effects that change middle and high frequency content into incoherent noise.

Air temperature can change suddenly with very audible effects (eg when backstage doors are opened during sound checks, venue doors are opened near the end of a show in winter or cold air displaces the warm air trapped in a stadium during a clear summer evening). Although quite rare, rapid air temperature changes can cause sudden changes in propagation direction and major coverage problems for a few fretful minutes before clearing. These sudden coverage changes often trigger sound system investigations as they tend to sound like mid or high frequency component failures or tripped amplifiers.

Humidity tends to change slowly with time and affects the higher frequencies. This slow change can be missed as our ear-brain system tends to compensate for subtle high frequency losses. If the relative humidity changes from, say, 25% at the beginning of a hot afternoon's sound check to 40% as the weather turns sultry, we may not notice the gradual 6dB increase in high frequency at the back of the field (3dB at the mix position) until the guest engineer arrives, having walked the field with a clean* pair of ears, and wants to change everything.

*Be aware that the human ear discharges more wax in humid conditions and this will tend to negate the improved high frequency propagation.

Although it is not possible to control the climate outdoors at the moment, a knowledge of its various effects on sound system performance will allow good system designers to minimise problems as follows:

1) Avoid trying to cover large outdoor areas with multiple, horizontally parallel

arrays. Keep mid & high frequency sections closely coupled at their optimum horizontal splay angles to minimise audible combing effects with crosswinds.

2) Avoid high, heavily tilted point source clusters as their propagation can be

refracted by temperature gradients or reflected by strong air layers causing major coverage problems. Use large, continuous vertical columns (from stage height to crane hook) to propagate sound almost parallel to the ground.

3) Design for at least 5º excess vertical and horizontal coverage to allow for

propagation shifts. If you don't have the extra equipment for this contingency, be prepared to retrim cluster tilts until the doors are about to open.

4) Where possible, take regular breaks outside the venue to avoid adapting to

humidity changes. If there is no time for breaks, ask trusted crew members for

their opinions or compare the system’s high frequency sound quality with a

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pair of high quality mix position monitors delayed back to the PA. The PA should sound warmer and more punchy but should never sound brighter than good monitors unless the man with the cheque book wants it that way.

5) Always get trusted sound crew members to walk the field during the show.

Their reports will be telling you more about climate changes than your system setup so don't be surprised if they ask for subsection level changes and eq adjustments. Major changes can occur when: i. the audience floods in (temperature gradients get disturbed and

humidity can rise)

ii. around sunset (temperature and local wind changes)

2a.2 Wind effects

Side winds

Gusting side winds can dramatically effect mid and high frequency sound by changing the propagation direction (and, therefore, the way adjacent radiators interact) as follows:

Single sound source

For example a 50km per hour (31 mph) side gust = approx 13.9m/s. The temporary change in direction during the gust = arctan 13.9/340 = approx arctan 0.041 = approx 2.3º

This may seem trivial until you realise that this sudden 2.3º change will shift a poorly arrayed system's polar pattern undulations about 2m to right at a typical outdoor mix position. Easily enough to swap high-mid and high frequency peaks and troughs several times in just a few seconds - an effect that went out of fashion in the 60s!

Variable combing (phasing) caused by wind effects should be minimised by avoiding widely spaced, parallel high frequency sections carrying the same signals.

Spaced, parallel loudspeakers will comb (add or subtract their outputs) depending on

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their distance or time offset from us (see Section 4.10). A 150mm/0.5ms offset at the listening position will cause nulls at 1KHz, 3KHz, 5KHz, 7KHz, 9KHz, 11KHz etc but we wouldn't be aware of the combing under casual listening conditions because we are used to listening to natural sounds in the presence of multiple arrivals (echoes) and our ear-brain system adapts to them. We don't adapt to varying comb structures though, especially in the horizontal plane, as our horizontally spaced ears act as a sensitive interferometer.

Martin Audio Wavefront Longthrow horns are stacked vertically and adjacent W8CTs may be flown in mirror image and splayed 30-40º (for coherent arraying) to minimise high frequency combing in breezy outdoor conditions. Widely spaced, parallel columns – carrying the same signal - should be avoided.

Where budgets allow, mono centre clusters should be used for lead vocals and instrumentals. Large ensembles (such as large string sections or large choirs) should be divided into multiple subgroups which are sent to separate clusters.

|< 0º >|< 0º >|< 0º >|

W8CM W8CT W8CT W8CT

Spaced, parallel columns – Bad in windy conditions

|< 0º >|<30-40º>|< 0º >|

W8CM W8CT W8CT W8CT

Splayed, tightly packed columns – Better in windy conditions

Wind gradient

30m

20m

10m

0m 10m 20m 30m 40m 50m 60m 70m 80m 90m

Wind Stronger

Wind Weaker

Sound path tilting upwards outdoors due to wind blowing towards loudspeakers

30m

20m

10m

0m 10m 20m 30m 40m 50m 60m 70m 80m 90m

Wind Stronger

Wind Weaker

Sound path tilting downwards outdoors due to wind blowing away from loudspeakers

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Air movement is slowed by friction so wind is usually lighter near the ground than it is higher up. Ground level wind speeds can vary from over 90% of the main wind speed in the daytime, when the air is being mixed by being warmed by the ground, to under 30% at night, when air - cooled by the ground - looses buoyancy.

This varying wind speed with height is called the wind gradient. A wind gradient associated with wind blowing towards a loudspeaker will "slow" its

vertical wavefront differentially. The vertical wavefront will be slowed less near the ground and its sound path will veer upwards.

Conversely, a wind gradient associated with wind blowing from behind a loudspeaker system will "speed up" its vertical wavefront differentially. The vertical wavefront will be speeded up less near the ground and its sound path will veer downwards.

Local winds

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Air absorbs very little heat from the sun's rays. It is indirectly heated by contact with warm surfaces. It also relies on contact with cooling surfaces to lose heat.

A local, anabatic wind can be set up by air rising up a slope warmed by the morning sun.

The same slope may cool the air at night causing it to flow down hill to form a katabatic wind. To maintain coverage, loudspeaker cluster tilts may need to be readjusted between morning orchestral rehearsals for a major outdoor event and the actual show.

Gusts and squalls

On a fair day when the ground is warm and clouds are forming and being moved by a very light breeze, local winds may vary in direction and strength as illustrated below.

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Local winds may be even more erratic in showery weather. Dramatic down-drafts of cold air may occur causing local squalls.

Graph showing main wind speed (dark colour) and gusts (light colour)

over several hours

The above main wind and gust plot shows that gusts can be more erratic in nature and several times stronger than the main wind. Their effects will be far more audible than a steady wind.

Anti-phasing eq

It may be advisable to roll off the system's high frequency response during gusts and squalls as a decreasing hf response sounds more natural than the incoherent swishing noise associated with phasing. A single pole (6dB per octave) high cut filter with a variable knee control down to 8KHz works well.

2a.3 Temperature effects

30m

20m

10m

0m 10m 20m 30m 40m 50m 60m 70m 80m 90m

Sound path tilting upwards outdoors due to normal temperature decrease with height

Cooler

Warmer

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The speed of sound varies with air temperature:

This means that the speed of sound can vary from 331.5m/s to 354.9m/s between 0ºC and +40ºC.

Temperature Gradient

As mentioned in Section 2a.2, air is a poor heat conductor and relies on its contact with surfaces to heat up and cool down.

On a clear, warm, sunny day the ground will warm low level air and the atmosphere will heat up, by convection, from bottom to top. Warm air cannot rise to the top of the atmosphere because air pressure drops with height and air temperature falls as the pressure falls.

Sound will travel faster near the ground and slower higher up causing its path to be tilted upwards.

If the sky remains clear after sunset, the ground will cool and draw heat from the air

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in contact with it. Air nearest the ground may get cooler than the air above it. In the absence of wind, this cool air may stay near the ground on a still night.

60m 50m 40m 30m 20m 10m 0m

0˚C 10˚C 20˚C

Temperature inversion

The same "inverse temperature gradient" can form above ice rinks and in most indoor venues. Sound will now travel slower near the ground and faster higher up causing its path to be tilted downwards.

30m

20m

Warmer

10m

0m10m20m30m40m50m60m70m80m90m

Sound path tilting down indoors due to high level heating or low level cooling (eg. ice rink) or outdoors due to cooling ground

Cooler

2a.4Relative humidity effects

Air absorption is quoted in dB/m and occurs over and above the usual sound pressure level changes caused by an expanding wavefront quoted in dB/doubling of distance.

Air absorption changes with relative humidity and temperature but these changes are complex - particularly where the humidity is low and the temperature varies a lot.

0.3dB/m

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10KHz

0.2dB/m

6KHz

Absorption coefficient

0.1dB/m

0dB/m

10%0

Relative Humidity

3KHz

1.5KHz

20%30%40%50%60%70%80%90%

In this example, high-mid and high frequency air absorption characteristics are quite complex at low relative humidity. Mid frequency absorption increases with increasing humidity, reaches maximum attenuation at about 5% RH and then starts to drop again. High-mid frequency absorption increases with increasing humidity, reaches maximum attenuation between 5 and 15% RH and then starts to drop again. High frequency absorption increases with increasing humidity, reaches maximum attenuation between 15 and 20% RH and then starts to drop again.

At the higher relative humidity (above 20% RH) found in temperate latitudes, absorption generally decreases with increasing relative humidity. This means that high frequency sound propagation improves as the relative humidity rises … but this is not always obvious in warmer weather as our ears produce more secretions when we perspire.

Note that, even at high relative humidity, we will still loose 10dB at 10KHz over 100m. Martin Audio Wavefront Longthrow systems provide the extra high-mid and high frequency headroom to cope with this air absorption.

Humidity changes can be a problem indoors too. On rainy days, damp audiences in large venues can cause temporary humidity increases that can make a well soundchecked system sound too harsh and fizzy. Be prepared to back off any mid and high frequency compensation until the venue's air conditioning has caught up.

Longthrow systems should be corrected with caution and distant audience areas rechecked at regular intervals during large events.

The Martin Experience

Wavefront Compact Series

Applications Guide

Section 3

Wavefront W8CS

Flown Subwoofer

CONTENTS

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MARTIN AUDIO

LONDON

Section 3

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Wavefront W8CS Flown Subwoofer

Contents

3.1 Introduction

3.2 Specifications

3.3 Pin-outs and cabling

3.4 System patching

3.5 DX1 Loudspeaker Management System

3.6 Power amplifier recommendations

3.6.1 Martin Audio MA4.2 Power Amplifier Overview

3.7 Adding W8CS’ to flown W8C systems

Wavefront W8CS Flown Subwoofer

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3.1Introduction

The Martin Audio Wavefront W8CS Flown Subwoofer comprises a special 15" high excursion driver coupled to an efficient mid-bass horn with a sub-bass port. This unique combination gives the W8CS the characteristic punch of a horn-loaded system with the low frequency bass extension of a reflex enclosure.

The W8CS is a compact, light weight system in a trapezoidal cabinet. It has the same footprint as the popular W8C (Section 1) and has been engineered to extend the Wavefront Compact W8C's performance to below 45Hz.

W8CS’ may either be used as full bass subwoofers (up to120Hz) or may be flown as mid-bass sections (60-160Hz) to complement floor standing WSXs.

Like all flown Wavefront products, W8CS’ are fitted with MAN load-certified flying points and are designed to comply with the 12:1 safety factor specified by the German VBG70 standard when used with the compatible 12:1 flying systems. One important advantage of the MAN flying system is that inter-cabinet connections place a minimal load on the cabinets and, being external, can be load certified and inspected independently.

3.2Specifications

Type: Compact folded bass horn, port assisted

Frequency response: 45-200Hz +/- 3dB

Low frequency limit: -10dB @ 35Hz

Driver: 1 x 15" (380mm) long excursion

Rated Power: 800W into 8 ohms, 3200W peak Sensitivity: 105dB/W

Maximum SPL: 132dB continuous, 138dB peak

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Impedance: 8 ohms nominal

Connectors: 2 x Neutrik NL8

Cabinet construction: Birch Ply

Cabinet finish: Slate textured paint

Protective grille: Perforated steel

Grille finish: Grey paint

Dimensions (inc wheels): (W) 562mm x (H) 799mm x (D) 925mm

(W) 22.1ins x (H) 31.5ins x (D) 36.4ins

Flown weight: 61kg (134lb). Lid 4kg (9lb) extra

Before rigging, note colour coding! W8C has 2 black points per side

W8CS has 1 black point per side

W8CT has 2 orange points per side W8CM has 1 orange point per side

3.3 Pin-outs and cabling

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W8CS

NL8 W8CS

-1 Driver +1 Driver +

-2 Driver +2 Driver +

-3 n/c +3 n/c

-4 n/c +4 n/c

(See Section 1.3 for connector pin-out drawing)

3.3.1 Cable and panel connector part numbers

Please note the following part numbers when ordering loudspeaker connectors to make up cables and patch panels

Neutrik NL connectors NL8FC 8 pole cable (female)

NL8MPR 8 pole panel (male) NL8MM 8 pole inline coupler (male-male)

Connectors should be kept in good, clean, uncorroded condition to ensure full, undistorted loudspeaker performance. Corroded or damaged pins and sockets can cause severe distortion or loss of signal.

3.3.2 Recommended loudspeaker cable

Although only 4-core cable is required for W8CS’, many users will find it convenient to standardise on 8-core NL8 cables to avoid confusion when using other loudspeakers in the Wavefront range.

Cable run vs copper core cross sectional area

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Single W8CS Two W8CS’ paralleled at the

cluster.

Up to 50m 2.5mm² 6mm² (or 2 x 2.5mm² cores in parallel) Up to 100m 6mm² 10mm² (or 2 x 6mm² cores in parallel)

Q. Why the odd sizes? A. Loudspeaker cables are available in a limited range of standard copper core sizes -

ie. 1.5mm², 2.5mm², 4mm², 6mm², 10mm² and 35mm².

3.4 System patching

Refer to Section 1.4 and Section 2.4 for general Wavefront patching suggestions and examples.

Bass sub-mix operation

Many mix operators prefer to create a separate sub-mix for bass/mid-bass sections. This is good practice as it helps provide main system headroom for those allimportant vocals and solos whilst allowing for larger-than-life percussion and bass instrument mixes without intermodulation and distortion.

This configuration can easily be programmed into the Martin Audio DX1 Loudspeaker Management System. The following illustrates a DX1 set up to control an active (3-way) Wavefront W8C system with W8CS’ (configured as a flown midbass section) augmenting floor-stacked WSXs.

Flying W8CS’ as a mid-bass section eliminates the problem of mid-bass absorption experienced with densely packed standing crowds.

3.5DX1 Loudspeaker Management System

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Refer to Section 1.5 for general information on the Martin Audio DX1 Loudspeaker Management System including configuration examples.

3.5.1DX1 Output Gain and Limiter settings for W8CS’

Standardising on one good model of power amplifier (preferably the Martin Audio

MA4.2)and correctly set-up controller (preferably the Martin Audio DX1) will

provide the most dynamic system performance and protection whilst simplifying design and reducing spares inventories. (See Section 1.5 and DX1 Speaker

Management System User's Guide for further details)

Gain settings

W8CS - assuming 800Wcont - 1600Wpk into 8ΩΩ power amplifiers: Best-fit Initial DX1

Amplifier Amplifier Amplifier Output GAIN Example Sensitivity Gain

dBu VrmsdB dB

Crown MA5002VZ (0.775v)-2 0.62 42 -9 Martin MA4.2** (41dB) -1 0.69 41 -8

Crest CA18 (x115) -1 0.69 41 -8

Crown MA3600VZ (0.775v)-1 0.69 41 -8

0 0.77 40 -7

+1 0.87 39 -6

+2 0.98 38 -5

+3 1.09 37 -4

QSC PL236/PL236A (36dB)+4 1.23 36 -3

+5 1.38 35 -2

+6 1.55 34 -1

+7 1.73 33 0

Martin MA4.2** (32dB) +8 1.95 32 +1

Crest 8001 (x40) +8 1.95 32 +1

Crest 9001 (x40) +8 1.95 32 +1

QSC PL236A (32dB) +8 1.95 32 +1

+9 2.18 31 +2

+10 2.45 30 +3

+11 2.75 29 +4

+12 3.08 28 +5

+13 3.46 27 +6

Crown MA3600VZ (26dB)+14 3.88 26 +7

Crown MA5002VZ (26dB)+14 3.88 26 +7

QSC PL236A (26dB) +14 3.88 26 +7

** Set Martin Audio MA4.2 rear MLS switch to 0dB to match peak output of unregulated power amplifiers.

Cluster balance (eg farfield-to-midfield or inner-to-outer) should be adjusted at the

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power amplifier controls to maintain limiter tracking. See Section 3.7.

Limiter settings

The Rated Power specification in Section 3.1 indicates the maximum long-term power dissipation that can be tolerated before driver ageing or damage occurs through overheating or over-excursion.

When choosing power amplifiers, do not be tempted to exceed the 800W into 8Ω power rating unless the amplifier's power rails are well regulated (see Section 3.6) even with properly set controllers in place. Although Martin Audio drivers are mechanically designed to survive normal road use and the occasional operator error, overpowered or bridged amplifiers can cause over-excursions that stress and age drivers. The best way to get the clean, relaxed sound of an overpowered amplifier is to choose an amplifier with plenty of current reserve - ie an amplifier with good 2Ω specification - and avoid running more than two cabinets in parallel.

To ensure transparent limiter operation without obvious distortion or pumping, the DX1 limiter attack and release times are factory preset to be inversely proportional to the subwoofer's high pass frequency as follows:

High pass filter range Attack time Release time

>31Hz 45mS 720mS 31Hz - 63Hz 16mS 256mS (63Hz high pass may be used when W8CS crossing in as a mid-bass)

These attack times allow the power amplifiers to clip momentarily but not for long enough to be obvious to listeners or cause driver overheating. It is quite normal to see amplifier clip indicators on the odd programme peak but continuous clipping would indicate a cable short circuit, wrong controller settings, excessive power amplifier gain or low mains voltage.

The following initial DX1 output limiter settings will avoid voice coil overheating and minimise amplifier clipping for high quality, trouble free operation.

W8CS - assuming 800Wcont - 1600Wpk into 8ΩΩ power amplifiers:

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Best-fit Recommended Amplifier Amplifier Amplifier DX1 LIMITER Example Sensitivity Gain Settings

dBu Vrms dB dBu

Crown MA5002VZ (0.775v) -2 0.62 42 -3 Martin MA4.2** (41dB) -1 0.69 41 -2

Crest CA18 (x115) -1 0.69 41 -2

Crown MA3600VZ (0.775v) -1 0.69 41 -2

0 0.77 40 -1

+1 0.87 39 0

+2 0.98 38 +1

+3 1.09 37 +2

QSC PL236/PL236A (36dB) +4 1.23 36 +3

+5 1.38 35 +4

+6 1.55 34 +5

+7 1.73 33 +6

Martin MA4.2** (32dB) +8 1.95 32 +7

Crest 8001 (x40) +8 1.95 32 +7

Crest 9001 (x40) +8 1.95 32 +7

QSC PL236A (32dB) +8 1.95 32 +7

+9 2.18 31 +8

+10 2.45 30 +9

+11 2.75 29 +10

+12 3.08 28 +11

+13 3.46 27 +12

Crown MA3600VZ (26dB) +14 3.88 26 +13

Crown MA5002VZ (26dB) +14 3.88 26 +13

QSC PL236A (26dB) +14 3.88 26 +13

** Set Martin Audio MA4.2 rear MLS switch to 0dB to match peak output of unregulated power amplifiers.

Use lower settings (or more subwoofers!) if your power amplifiers indicate clipping on more than just the odd peak. Excessive clipping may also be caused by inadequate power amplifier reserve or an inadequate mains supply. See Section 3.6.

3.6Power amplifier recommendations

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The Wavefront Compact Subwoofer has been designed and manufactured for very high performance but will not give that performance unless power amplifiers are chosen and used intelligently.

Power capability

W8CS’ provide full performance when driven by professional power amplifiers capable of delivering undistorted output power into a range of loads as follows:

W8CS

800 W(AES) into 8 ohms 1,600 W(AES) into 4 ohms and 3,200 W(AES) into 2 ohms

Please note:

Amplifiers with excessive output may damage voice-coils or age driver suspensions due to excessive heat dissipation and excursion.

A note about power amplifier output specifications

Martin Audio MA series power amplifiers have regulated rails so it is quite permissible to use slightly overpowered models - with suitably set controller limiters

- without risking uncontrolled power bursts. The MA series power amplifiers’ regulated power rails also ensure maximum performance under the real-world concert conditions of less-than-optimum mains supplies and low impedance loads. See

Section 3.6.1 for further details.

Amplifier load tolerance

An efficient subwoofer system in live concert conditions can act as a surprisingly dynamic and complex load. Most modern touring power amplifiers claim 2 ohm capabilities but make sure your amplifier is also capable of driving reactive (ie inductive or capacitive) loads without prematurely clipping or developing output stage crossover distortion.

Power reserve

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Most power amplifier specifications are based on bench measurements made using stable, high current mains supplies and well defined loads. Amplifiers sound best when they have plenty of current in reserve for percussive peaks and sustained bass notes.

1) Try to ensure that the mains supply stays within the amplifier manufacturer’s

specified range from no load to maximum load. An electrical technician should check the mains supply vs demand using an

accurate rms voltage meter.

2) If unfamiliar generators are being used the electrical technician should check

the mains waveform (using a portable ’scope-meter) to make sure that it is sinusoidal and not crawling with spikes or interference.

3) Avoid driving too many W8CS’ in parallel. I would suggest no more

than two so that the power amplifier’s 2 ohm spec is kept in reserve for musical peaks.

4) Avoid using power amplifiers in bridged mode. Most commercial power

amplifiers are optimised for 2-channel operation. It is usually better to use the appropriate amplifier in 2-channel mode than to use an inadequate amplifier in bridged mode.

Power amplifier gain or level settings reminder

Gain switches

Level controls

The front panel level controls should be turned down (fully counter clockwise) until FOH-to-Amp rack lines have been checked and controllers have been set to suit the power amplifiers to be used (see Section 3.5). Music should be used to check that controllers are receiving and sending the appropriate signal bands and then each power amplifier level control advanced in sequence to check system operation and patching.

Assuming that controllers have been set as tabulated in Section 3.5, power amplifier level controls should be set to full (fully clockwise) for loudspeaker sections requiring the strongest drive. Amplifiers driving nearer-field sections within the same cluster

may be backed off as required for smooth coverage. This process will ensure that

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the cluster coverage remains balanced during limiting.

Rack mounting

As with main W8C systems, always leave a 1U space between big subwoofer power amplifiers and controllers. Although most modern amplifiers don’t radiate significant fields it's better to play safe and keep the system free from hum & buzz. Rear supports are recommended. Check the manufacturer's application notes for details.

3.6.1 Martin Audio MA4.2 Overview

Features

Ø Switch mode power supply Ø Superior sonic performance Ø Light weight Ø Advanced protection circuits Ø Efficient copper cooling system Ø Minimum load switches (MLS

)

The MA4.2 power amplifier has been designed to combine reliability and high power output with sonic excellence. Utilising an advanced switch mode power supply, the MA4.2 is characterised by a very high power-to-weight ratio, in a lightweight, 2U package.

See MA4.2 Power Amplifier User's Guide for detailed operating instructions.

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Cooling System

The Martin Audio MA4.2 amplifier runs very cool due to a special patented copper cooling system. The amplifier’s bi-polar output devices are mounted directly onto a copper heat sink (copper conducts heat twice as efficiently as aluminium) and maximum heat dissipation is achieved by turbulent airflow over the heatsink’s geometric fins.

The MA4.2 amplifier features two proportional speed cooling fans which take in air from the front of the amplifier and exhaust from the rear. A horizontal pressure chamber between the heatsink and the cooling fans ensures that there is little difference in the operating temperatures of each output device. In contrast, a conventional tunnel design can result in a temperature variance of up to 40° between output devices.

Switch Mode Power Supply

The MA4.2’s switch mode power supply (SMPS) is the modern solution to the problems of size and weight. Switch mode power supplies are not new - they are found in computers and televisions. However, the demands of high power audio are very different to these applications. The MA4.2 overcomes the size and weight constraints of conventional power supplies whilst at the same time avoiding the pitfalls of typical switch mode designs.

Efficiency is also maximised. With much smaller transformers than a conventional supply, there is much less loss due to transformer resistance and much less power wasted as heat in the power supply.

Regulation of the SMPS means that the power amplifier will produce the same power output, even if the AC line voltage drops by 20%.

Minimum Load Switches (MLS™)

Protection

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The MA4.2 amplifier has many advanced protection features that will protect both the amplifier and the speakers connected to it, under fault conditions. All protection circuits are independent and inaudible in normal use.

Clip Limiters

Thermal Protection

Thermal Protection circuitry prevents the amplifier from running at an unsafe temperature by muting the input signal when the internal temperature rises above 90°C.

Short Circuit Protection

The MA4.2 amplifier is completely short circuit protected. The protection circuits permit very high peak currents, but maintain the output devices within their safe operating area.

Mains Voltage Protection

This operates if the mains voltage falls outside its permitted operating range. If this occurs, the power supply will shut down until the correct mains voltage is restored.

DC and VHF Protection

Both DC voltages and high power VHF signals can cause damage to loudspeakers. The MA4.2 amplifier incorporates protection circuits which are activated when damaging DC voltages or VHF signals are present at the outputs.

MA4.2 Specifications

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Input Impedance 20kohms (balanced) 10kohms single ended Gain select switch 41dB (I/P sens 0.775V), 32dB (I/P sens 2.26V) CMRR at 1KHz >50dB Output impedance at 1KHz <0.06 ohms Power Bandwidth 5Hz - 20kHz Slew rate 20V/us Hum/Noise <-95dB Channel Separation 1kHz > 80dB

10kHz > 70dB

Mains Operating Voltage 120 – 270 (minimum start voltage 190)

full output power maintained 180 – 280V. Optional (65 - 135V) operation.

Protection DC, High temperature, Turn on, VHF,

Over and under voltage, Clip limiters.

AFS Short circuit. Distortion THD 20Hz - 20kHz and 1W – 1000W THD at 1 kHz and 2000W DIM 30 at 500W CCIF (13 and 14kHz) at 500W SMPTE (60Hz and 7kHz) at 500W

4 ohms 0.1%

4 ohms 0.04%

Power Matrix

MLS SWITCH SETTING LOAD CONFIGURATION 16 ohms Stereo (2 channel) 8 ohms Stereo (2 channel) 4 ohms Stereo (2 channel) 2 ohms Stereo (2 channel)

16 ohms Bridged mono 8 ohms Bridged mono 4 ohms Bridged mono

Weight 10kg (22lbs) Dimensions (W) 483mm x (H) 88mm x (D) 347mm

(-5dB) (-4dB) (-2dB) (0dB)

220W 260W 410W 650W

430W 520W 820W 1300W

830W 1000W 1600W 2100W

1660W 2000W 2200W 2400W[1]

3050W[2] 3200W[2]

860W 1040W 1640W 2600W

1660W 2000W 3200W 4200W

3320W 4000W 4400W 4800W[1]

(W) 19ins x (H) 3.5ins x (D) 13.7ins

3.7 Adding W8CS’ to flown W8C systems

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Although the Wavefront W8C is often used as a base for smaller floor-stacked or stage-stacked systems (see Section 1.8), flying W8CS’ with main W8C systems can keep the floor tidy and free up floor space for scenery, TV camera tracks etc.

As mentioned earlier, very large outdoor festival crowds will absorb mid-bass from low-profile, ground stacked subwoofers. Flying W8CS’ as horn-loaded mid-bass complements the horn-loaded WSX subwoofers to provide an incredibly tight, efficient and detailed bass performance that will shift air and provide a phenomenal kick drum punch.

3.7.1 W8CS/W8C configurations

For medium power amplications - amplifying an large orchestra, for example, where low frequency stability is important - a single row of W8CS’ may be added to a

standard W8C cluster extending its low frequency response to below 45Hz. This

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configuration can be very efficient as it uses the rest of the cluster as a baffle, increasing forward projection allowing high gain before feedback.

The following iconic layout may be used to represent the above cluster:

30 30 30

20 20 20 20

20 20 20

30 30 30

30 30

Important reminder:

Splay angles are always quoted axis-to-axis - not between cabinet sides!

ie. 30 =

|‹ 30º ›|

W8CS’ flown in rows with W8Cs

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30 30

20 20

20 20 20 20

30 30 30

30 30

Multiple rows of W8CS’ increase low frequency headroom for higher power rock, dance club applications.

Note that flying W8CS’ in rows keeps clusters relatively narrow where width is at a premium.

Coverage would be 145º horizontal x 70º vertical.

For very high power rock or dance applications, the above W8CS’ may be configured

as flown mid-bass elements (crossed in at 60Hz and out at 160Hz) to augment floor-

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stacked WSXs working as low subs below 60Hz. Refer to Section 2.4.

Power amplifier monitoring at real-world gigs have shown that half of the total system power is demanded between 60Hz & 160Hz during heavy rock and dance music.

W8CS’ flown in columns with W8Cs

20 20 20 20 20 20 20

15 15

20 20 20 20 20 20

15 15 15

Again, coverage would be 145º Horizontal x 70º Vertical.

Flying W8CS’ in columns between W8C columns keeps clusters shorter whilst

providing good vertical control for minimum roof excitation.

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W8CS’ may be flown as fullbass where floor space is required for TV cameras or may be configured as flown mid-bass elements to complement floor-stacked WSXs.

For further information on suitable Wavefront subwoofer systems and a brief tutorial on bass stack sizes and shapes vs coverage see Section 4.

The Martin Experience

Wavefront Compact Series

Applications Guide

Section 4

Wavefront WSX

Folded Horn

Subwoofer

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MARTIN AUDIO

LONDON

Section 4

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Wavefront WSX Folded Horn Subwoofer

Contents

4.1 Introduction

4.2 Specifications

4.3 Pin-outs and cabling

4.4 System patching

4.5 DX1 Loudspeaker Management System

4.6 Power amplifier recommendations

4.7 Placement

4.8 WSX application examples

4.9 Further examples

4.10 Spaced systems

4.11 Electronic steering

Wavefront WSX Folded Horn

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Subwoofer

4.1Introduction

The powerful WSX folded horn subwoofer is designed to complement Wavefront Series W8C touring systems to provide deep bass with maximum efficiency, speed and impact. Its classic Martin ‘S’ shaped folded horn is over 7 feet (2.1m) long and couples a powerful 18” (460mm) long excursion driver to the airload with a modified hyperbolic expansion law.

4.2Specifications

Freq response: 38-150Hz +/- 3dB (half space)

LF limit: -10dB @ 28Hz

Rated Power: 600W into 8 ohms, 2400W peak

Sensitivity: 105dB (half space with band limited pink noise)

Maximum SPL: 132dB continuous, 138dB peak (half space with band limited

pink noise)

Impedance: 8 ohms nominal

Crossover Freq: 150Hz or below

Crossover System: Martin Audio DX1 Loudspeaker Management System,

MX4 or MX5. (See operating instructions)

Connectors: 2 x Neutrik NL8

Dimensions: (W) 572mm x (H) 1066mm x (D incl wheels) 1065mm

(W) 22.5ins x (H) 41.9ins x (D incl wheels) 41.9ins

Weight: 96kg (211 lbs)

4.3 Pin-outs and cabling

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WSX

NL8 WSX

-1 Driver +1 Driver +

-2 Driver +2 Driver +

-3 n/c +3 n/c

-4 n/c +4 n/c

(See Section 1.3 for connector pin-out drawing)

Martin audio WAVEFRONT COMPACT APPLICATIONS GUIDE

Specifications and Main Features

Frequently Asked Questions

User Manual

Wavefront Compact Series

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