Meyer LD-3 Operating Instructions Manual

OPERATING INSTRUCTIONS
LD-3 Air Attenuation Compensating Line Driver
Keep these important operating instructions.
Check www.meyersound.com for updates.
DECLARATION OF CONFORMITY ACCORDING TO ISO/IEC GUIDE 22 AND EN 45014
European Office: Meyer Sound Lab. GmbH Carl Zeiss Strasse 13 56751 Polch, Germany
Made by Meyer Sound Laboratories Berkeley, California USA
Manufacturer's Name:
Meyer Sound Laboratories Inc.
2832 San Pablo Avenue Berkeley, CA 94702-2204, USA
declares that the products Product Name: LD-3 Line Driver Product Options: All
conforms to the following Product Specications
Safety: EN 60065:1998 EMC: EN55103-1: 1997 emmission
EN55103-2: 1997 immunity
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This device complies with the requirements of the Low Voltage Directive 73 / 23 / EEC and the EMC Directive 89 / 336 / EEC.
This device also complies with EN 55103-1 & -2. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.
Supplementary Information
The product herewith complies with the requirements of the Low Voltage Directive 73/23/EEC and the EMC Directive 89/336/EEC.
Ofce of Quality Manager Berkeley, California USA July 3, 2003
European Contact: Your local Meyer Sound dealer or Meyer Sound Germany, GmbH. Carl Zeiss Strasse 13, 56751 Polch, Germany. Telephone: 49.2654.9600.58 Fax: 49.2654.9600.59
Environmental specications for Meyer Sound Electronics products
Operating temperature 0°C to +45°C Non-operating temperature -40°C to +75°C Humidity to 95% at 35°C Operating altitude to 4600 m (15,000ft) Non-operating altitude to 6300 m (25,000ft) Shock 30 g 11 msec half-sine on each of 6 sides Vibration 10 Hz to 55 Hz (0.010 peak-to-peak excursion)
© 2003 Meyer Sound. All rights reserved. LD-3 Operating Instructions
The contents of this manual are furnished for informational purposes only, are subject to change without notice, and should not be construed as a commitment by Meyer Sound Laboratories Inc. Meyer Sound assumes no responsibility or liability for any errors or inaccuracies that may appear in this manual. Except as permitted by applicable copyright law, no part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, recording or otherwise, without prior written permission from Meyer Sound.
Meyer Sound, Meyer Sound MAPP Online, SIM and QuickFly are registered trademarks of Meyer Sound Laboratories Inc. (Reg. U.S. Pat. & Tm. Off.). All third-party trademarks mentioned herein are the property of their respective trademark holders.
Printed in the U.S.A.
Part Number: 05.118.040.01 B
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SYMBOLS USED
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These symbols indicate important safety or operating features in this booklet and on the chassis:
Dangerous voltages: risk of
electric shock
Pour indiquer les risques
résultant de tensions
dangereuses
Zu die gefahren von
gefährliche spanning zeigen
Para indicar voltajes
peligrosos.
Important operating
instructions
Pour indequer important
instructions
Zu wichtige betriebs-
anweisung und unter-
haltsanweisung zeigen
Instrucciones importantes
de funcionamiento y/o
manteniento
IMPORTANT SAFETY INSTRUCTIONS
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Do not use this apparatus near water.
6. Clean only with dry cloth.
7. Do not block any ventilation openings. Install in accordance with Meyer Sound's installation instructions.
8. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus that produce heat.
9. Do not defeat the safety purpose of the grounding­type plug. A grounding-type plug has two blades and a third grounding prong. The third prong is provided for your safety. If the provided plug does not t into your outlet, consult an electrician for replacement of the obsolete outlet.
Frame or chassis Protective earth ground
Masse, châssis Terre de protection
Rahmen oder chassis Die schutzerde
Armadura o chassis Tierra proteccionista
11. Only use attachments/accessories specied by Meyer Sound.
12. Use only with the caster rails or rigging specied by Meyer Sound, or sold with the apparatus. Handles are for carrying only.
13. Unplug this apparatus during lightning storms or when unused for long periods of time.
14. Refer all servicing to qualied service personnel. Servicing is required when the apparatus has been damaged in any way, such as the power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.
10. Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point where they exit from the apparatus. The AC mains plug or appliance coupler shall remain readily accessible for operation.
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CONTENTS
INTRODUCTION 1
How to use this manual 1 Introducing The LD-3 Air Attenuation Compensating Line driver 1
CHAPTER 1: AC Power Requirements 3
CHAPTER 2: Audio and System Controls 5
Audio Input 5 Atmospheric Correction 5
Temperature 6 Altitude 6 Relative Humidity 6
Array Correction 6
Array Type 7
Array Size 7 The Enter Button 7 Master Input Channels A and B 8 Channels 1-3 (A and B) Outputs 8
Distance Control 9
Insert Switch 10
Insert Inputs 10
Send Outputs 10 Subs A and B 10
Insert Switch 11
Insert Inputs 11
CHAPTER 3: System Design, Integration, and Optimization 13
Example Design Congurations 13 Meyer Sound MAPP Online® 13 Loudspeaker/Subwoofer Integration 14 SIM® Measurement System 15
Source Independent Measurement Technique 15
Applications 15
Appendix A: Specications 17
Appendix B: Example Congurations 19
Appendix C: Signal Flow Diagram 22
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INTRODUCTION

INTRODUCTION

HOW TO USE THIS MANUAL

As you read this manual, you’ll nd gures and diagrams to help you understand and visualize what you’re reading. You’ll also nd numerous icons that serve as cues to ag important information or warn you against improper or potentially harmful activities. These icons include:
A NOTE identies an important or useful piece of information relating to the topic
under discussion.
A TIP offers a helpful tip relevant to the topic at hand.
A CAUTION gives notice that an action can
have serious consequences and could cause harm to equipment or personnel, delays, or other problems.
By utilizing multiple-variable atmospheric loss equations and pre-calculated Meyer Sound MAPP Online® (for more information, see Chapter 3) stored values, the LD-3 delivers results quickly and efciently. Its high-quality, digitally­controlled analog lters provide the best of both worlds: the low latency and wide dynamic range of analog and the nimble, precise, repeatable results of digital. The LD-3 corrects frequency response up to 16 kHz at a resolution down to 1 dB.
Figures i.2, i.3, and i.4 are example frequency attenuation curves for three different temperatures with a xed distance of 100 meters, at seven values for relative humidity. Depending on the atmospheric conditions and the distance the array is throwing, the number of possible correction combinations is staggering – and achievable with the LD-3.

INTRODUCING THE LD-3 AIR ATTENUATION COMPENSATING LINE DRIVER

Once a challenge to line array system design, environmental conditions are just another part of the mix with the eight­channel LD-3 (Figure i.1), a powerful tool from Meyer Sound for optimizing large-scale sound reinforcement systems by correcting frequency response for the attenuation of sound in air.
Figure i.1. LD-3 line driver, front and rear panels
Feed the day’s weather report into the LD-3 through its Atmospheric Correction and Relative Humidity knobs, dial-in the type of loudspeakers and distance of the throw for each section of the array, and the LD-3 goes to work. A RISC microcontroller retrieves response correction coefcients and corrects the output to compensate for the air absorption for those weather conditions.
Figure i.2. Air absorption for 10 degrees C at 100 meters
Figure i.3. Air absorption for 20 degrees C at 100 meters
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INTRODUCTION
Figure i.4. Air absorption for 30 degrees C at 100 meters
In addition to weather correction, the LD-3’s unique ability to compensate for low to mid-low frequency build-up allows the user to ne-tune each channel driving an M Series array. Set the type of loudspeaker being used and the number of cabinets in the array, and the LD-3’s stored presets do the rest.
Figure i.5 is an example of a correction made to a MILO array with eight loudspeakers. By applying this correction the result is an incredibly at system response across a wide range of frequencies.
Each of the LD-3’s two master channels consists of a Master Input section, a dedicated subwoofer output, and three outputs to required control. Three Sends and four Insert/Returns provide the control to route the signal and incorporate additional signal processing, such as parametric equalization.
The Master Input section provides individual channel Gain adjustment from –12 to +6 dB, an illuminated Mute switch, Signal/Clip indicator, and a switchable High-Pass Filter (0, 80, or 160 Hz) for boundary correction or optimizing crossover to subwoofers. Master environmental controls include Temperature (0° to 45° C), Altitude (switchable in three ranges: 0-800, 800-2200, and 2200+ m) and Relative Humidity (10 to 100%).
Individual outputs provide Gain trim from –6 to +6 dB, Signal/Clip indicator, an illuminated Mute switch, illuminated Send/Return Insert switches, and Distance controls to dene the throw from each sound system branch to its audience coverage area up to 150 meters (492 feet).
The LD-3’s dedicated subwoofer control sections feature Polarity switches, Gain trim from –6 to +6 dB, mute, Signal/ Clip/Mute indicator, and Send/Return Insert switches. In addition, a high-quality Low-Pass Filter is supplied, switchable to 0, 55, or 80 Hz.
NOTE: While each of the LD-3’s output fully
independent channels can be used to divide a main system into subsystems, they can also be used to control downll, front ll, and delay systems, allowing independent signal levels.
In addition to its sophisticated environmental and array control functions, the LD-3 can integrate different types of Meyer Sound self-powered loudspeakers into a cohesive system, while maintaining signal integrity for long cable paths.
The LD-3 occupies two standard 19-inch relay rack spaces. Flash memory for future expansion is built in, and all input and outputs are electronically balanced and utilize XLR (A-3) type connectors. The AC inlet is an IEC standard male
connector, protected with a 250 mA 250 V fuse, and switchable in the ranges of 105-125 and 210-250 VAC.
Figure i.5. Correction needed shown with eight MILO loudspeakers at 35 meters
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Information and specications are applicable as of the date of this printing. Updates and supplementary information are posted on the Meyer Sound web site at:
www.meyersound.com
You may contact Meyer Sound Technical Support at:
Tel: +1 510 486.1166
Fax: +1 510 486.8356
Email: techsupport@ meyersound.com
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CHAPTER 1: AC POWER REQUIREMENTS

The LD-3 uses an international standard IEC 320 mains AC inlet. This convenient rear panel receptacle accepts many power cord types for mains outlets used throughout the world. The LD-3 must have the correct power cord for the AC power in the area in which it will be used.
The LD-3 operates in two AC voltage ranges: 105 – 125 V and 210 – 250 V, at 50 or 60 Hz (Figure 1.1). The voltage select switch on the rear panel must be set to the proper voltage before applying AC power. Connecting the LD-3 to a 225 V AC source with the voltage select switch in the 105 – 125 V position could blow the fuse.
Voltage Select Switch
CHAPTER 1
CAUTION: Don’t use a ground-lifting
adapter or cut the AC ground pin. To avoid electrical shock and damage to the unit, use the power cord specied by Meyer Sound or an equivalent that satises the requirements of the local safety testing agency.
CAUTION: Do not operate the unit if the
power cables are frayed or broken.
IEC 320 Male Power Outlet
Figure 1.1. Voltage switch and power inlet locations on the LD-3
CAUTION: Always unplug the power cord
before changing the voltage select switch.
When the LD-3 is powering on, it takes about two seconds to read stored atmospheric and array correction values, and illuminated Enter button (covered in Chapter 3, “Audio and System Controls”) changes from red to green.
Audio outputs are muted internally during normal power on and off, and in case of sudden loss of AC power or unstable line voltage. This precaution prevents noise transmission — and possible damage — to interconnected devices.
Always disconnect the power cord before changing the fuse. To replace the fuse, insert a at-blade screwdriver in the fuse cap and gently turn counterclockwise; the fuse springs from its socket. Replace only with a 5 x 20 mm, T 250 mA, 250 V, time-lag fuse that conforms to identical safety agency standards. If the fuse blows again, contact Meyer Sound for repair information.
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CHAPTER 1
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CHAPTER 2: AUDIO AND SYSTEM CONTROLS

Much more than a system integration tool, the LD-3 line driver uses its sophisticated circuitry to bring consistent and predictable results to any M Series line or curvilinear array design. This chapter will help you understand and harness the power of the LD-3's audio and system controls.

AUDIO INPUT

The LD-3 presents a 10 kOhm balanced input impedance to a three-pin XLR connector wired with the following convention:
Pin 1 — Connected to Earth (AC) ground and chassis
through ESD (Electrostatic Discharge) absorption and EMI/RFI (Electromagnetic/Radio Frequency Interference) lters
Pin 2 — Signal (+)
Pin 3 — Signal (-)
Case — Earth (AC) ground and chassis
The LD-3 is balanced in and out, and consequently does not change the polarity unless the “Sub Polarity” switch is engaged on the Sub output section. Pins 2 and 3 carry the input as a differential signal. Use standard audio cables with XLR connectors for balanced signal sources.
Figure 2.1. The Atmospheric Control section is at the heart of the LD-3.
Controls are included for:
Temperature
Altitude (atmospheric pressure)
Relative humidity
Distance
CHAPTER 2
The audio input signal should always be applied between pins 2 and 3.
NOTE: All inputs employ ESD absorbers
and RF lters.
Pin 1 is connected to the unit's chassis and acts as a safety and current bleed to earth for the ESD and EMI/RFI interference coupled onto the shield of the input cable. Pin 1 is only for bleeding noise to ground, and connecting an audio signal between pins 1 and 2, or pins 1 and 3, results in a noisy audio signal. Most modern balanced audio sources (electronically balanced or transformer output) conform to the wiring convention described above and interface correctly with the LD-3.

ATMOSPHERIC CORRECTION

The LD-3’s Atmospheric Correction section (Figure
2.1) uses special atmospheric loss equations and pre­calculated Meyer Sound MAPP Online® stored values from a 2 MB lookup table to correct for key environmental conditions.
NOTE: The Distance controls – featuring
large green knobs to match the color of the green temperature and relative humidity knobs – are located in sections for individual Channels 1­3 (A and B) outputs, discussed later in this chapter.
NOTE: Atmospheric correction may be
disabled per channel on each of the three A and B Output Channels by setting the distance to zero.
Settings are read with 8-bit resolution and a range of coefcient indices are fed to the output channels. The result is corrected frequency response for the attenuation of sound in air up to 16 kHz, with a resolution of approximately 1 dB.
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CHAPTER 2
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CHAPTER 2

Temperature

The green Temperature control allows you to set temperature in 1° increments from 0° to 45° C. A convenient Fahrenheit (F) to Celsius (c) conversion table is located to the bottom left of the Atmospheric Correction section (Figure 2.2).
Figure 2.2. The LD-3 includes a temperature conversion reference table stenciled on its front panel.
Setting temperature is the rst step in the atmospheric correction chain; the LD-3 takes the temperature setting and uses it with the other environmental coefcients to nd the correction needed across the LD-3’s frequency range.

Altitude

The altitude switch supports three ranges:
0 to 800 m (0 to 2,624 ft) above sea level
800 to 2200 m (2,624 to 7,217 ft) above sea level
2200+ m (7,217 ft) above sea level
Setting the altitude noties the LD-3 of the atmospheric pressure; this setting corresponds to an index into a function which has been pre-solved; the LD-3 then changes how much output correction is needed due to different atmospheric pressure levels.

Relative Humidity

The green Relative Humidity control allows the user to dial-in relative humidity from 10 to 100% in increments from 1 to 5% (the incremental range increases as humidity increases).
The effect of humidity on the attenuation of sound is perhaps the most critical aspect of the LD-3’s environmental functionality, and is a fascinatingly complex topic all to itself (and well beyond the scope of this guide). Although it’s generally true that the LD-3 will boost frequencies (particularly high frequencies) at an increasing rate as temperature and altitude go up, the effects of humidity are more complex, with few observable ranges that show a consistent, incremental increase.
For instance, at 16 kHz and temperatures above 25° C, a critical range is roughly 10-30% humidity. As shown in Figure 2.3, the higher the humidity in this range, the less air attenuation at that frequency – drier air needs less boost (not a completely intuitive notion in any case).
However, at other humidities (not to mention other temperatures, altitudes and distances) outside of this example range, the rate and pattern of attenuation behaves in other, less intuitive ways.
Because the LD-3’s atmospheric control functions are logarithmic rather than exponential (unlike simple lters, for example), they will not always behave in ways you expect “normal” circuitry to behave. For instance, turning the Relative Humidity knob to right doesn’t mean that the LD­3 is necessarily adding more correction (it could be adding less).

ARRAY CORRECTION

The LD-3’s unique ability to correct the overall frequency response of the line or curvilinear array itself enables you to further ne-tune your system design to correct natural array behavoir, such as low frequency build-up.
Figure 2.3. Air Absorption per meter at 16 kHz
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The Array Correction section (Figure 2.4), lets you set the
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type of M Series loudspeaker using the Array Type selector switch and the number of cabinets in the array with the Array Size control.
CHAPTER 2
NOTE: The rmware and ROM (Read Only
Memory) which support the LD-3’s array correction functions are upgradeable in the eld. Contact Meyer Sound or visit the Meyer Sound Web site at www.meyersound.com for more information on when this feature and upgrades will be available.

Array Size

You can set the number of cabinets in your array – up to 24 loudspeakers per channel – using the gray Array Size control. For example, if you have two MILO arrays (typically a left and right array) of 12 cabinets each, you would set the Array Size selector to 12.
NOTE: Setting the Array Size selector to 1
disables Array Correction functionality.
Figure 2.4. The LD-3’s Array Correction section

Array Type

The gray Array Type selector (the top knob in the Array Correction section) is a switch that controls the assignment of the LD-3’s Array Correction function to any of the following M Series loudspeakers:
M1D ultra-compact curvilinear array loudspeaker
M2D compact curvilinear array loudspeaker
MILO high-power curvilinear array loudspeaker
M3D line array loudspeaker
The Remote setting of the Array Type selector (bottom right side) is for establishing a data link with MAPP Online and downloading a pre-calculated array correction into the LD-3.
TIP: Setting the selector to Remote disables
the Array Size selector (covered in the next
section).
Array correction is also applied to the Sub outputs, and, when active, attenuates the Sub outputs. The Sub section’s Gain trim, from –6 to +6 dB, should be used if additional Gain on the Sub outputs is needed.

THE ENTER BUTTON

When the controls in the Atmospheric and Array Correction sections are adjusted, press the illuminated Enter button (Figure 2.5) to enable the changes.
Figure 2.5. The Enter button
Use the Enter button each time a change is made for the following LD-3 functions:
Temperature
Altitude
After loading data via the LD-3’s serial Data Port, the Program Loaded LED light, located just below the Remote setting, illuminates.
CAUTION: An unlabeled notch – reserved
for future use – exists between the M3D and Remote settings on the Array Type selector. Setting the selector to this notch disables Array Correction functionality.
Relative humidity
Distance (in any channel)
Array Type
Array Size
The Enter button changes from green to red once a change is made on any of the above controls, indicating that it needs to be pressed to update your changes; when the Enter button is pressed, the LD-3 registers the change(s) and the Enter button changes back to green.
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CHAPTER 2
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CHAPTER 2
For example, if the Temperature is set to 25° and the Relative Humidity to 40%, press Enter, then change the Temperature to 30°; press Enter again for the LD-3 to register the new temperature.

MASTER INPUT CHANNELS A AND B

Master input channels A and B (Figure 2.6) are equipped to control a full-range main system.
Front Panel Rear Panel
Figure 2.6. Master input channels A and B
These lters are used to optimize integration with subwoofers; in several cases they can augment an array’s headroom by ltering low frequencies out.
NOTE: When driving loudspeakers with high-
pass lters and/or subwoofers with low-pass lters engaged, phase shift caused by the lters in the region where frequencies overlap may require that you change subwoofer polarity — even if they are co-planar or near each other.

CHANNELS 1-3 (A AND B) OUTPUTS

Six individual output channels – three for each Master Input channel –provide Gain trim, illuminated Mute switches, Signal/Clip indicators, and Insert switches (Figure 2.7). In addition, individual distance controls dene the throw from each sound system branch to its audience coverage area up to 150 meters.
Front Panel
Each Master Input channel has an illuminated mute switch, signal/clip LED indicator, a switchable high pass lter, and gain. For each channel, the controls perform these functions:
The gain control sets the overall level from –12 to +6 dB.
The illuminated Mute switch mutes all channel outputs,
which ash red when muted.
NOTE: When muting a master channel, you
are effectively muting the individual output circuits located for each sub-channel. Hence each output channel Mute switch will ash red, but its Signal/Clip LED will still be active.
The bi-colored Signal/Clip LED indicates input signal
presence and level with a variable intensity green color, and clipping with ashing red.
The High Pass Filter switch lters the input signal at
0, 80, or 160 Hz for boundary correction or optimizing crossover to subwoofers. The lter affects Channels 1-3 for each Master Input channel A and B.
NOTE: The High-Pass Filter set to 160 is
identical to setting the “Lo-cut” lter on the LD-1A and LD-2 line drivers; it is a 2nd Order (12 dB/ octave) at 162 Hz with a Q of 1.82. The 80 Hz lter is an elliptical lter with fast initial attenuation – without the phase shift associated with lters of higher order.
Rear Panel
Figure 2.7. The LD-3’s output channel section
For each channel, the controls perform these functions:
The Gain control sets the output level from –6 to +6 dB.
The illuminated Mute switch mutes the channel, ashing
red when muted.
The bi-colored Signal/Clip LED indicates signal
presence and level with a variable intensity green color, and clipping with ashing red.
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NOTE: Although the LD-3 offers a large gain
range (-6 to +6 dB) for each output, gain tapering is not recommended for arrays. Adjusting zones with an overall amplitude control for each zone results in the following:
1. Directionality decreases.
2. Low-frequency headroom decreases.
3. The length of the line or curvilinear array column is effectively shortened.

Distance Control

The green Distance control allows you dial-in the throw from the array on each output channel, from 0 to 150 meters.
NOTE: Setting distance to 0 meters bypasses
the atmospheric correction functions.
CHAPTER 2
Figure 2.8. The LD-3 includes an easy distance conversion reference table stenciled on its front panel.
Setting the Distance enables the LD-3 to adjust the correction curve according to the throw of the loudspeakers on each channel. This setting corresponds to coefcients (in increments from 2 to 10, increasing as distance increases) which provide just the right amount and shape of correction as a function of the other atmospheric variables (Temperature, Altitude, and Relative Humidity). As suggested by Figure 2.9, there are a multitude of correction scenarios for even a handful of distances.
A convenient feet (ft) to meters (m) conversion table is located to the bottom left of the Atmospheric Correction section (Figure 2.8).
NOTE: After dialing in a new distance for any
channel, press the Enter button.
Figure 2.9. Sample atmospheric correction curves for the attenuation of sound in air at 10, 20, 40 and 80 meters.
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CHAPTER 2
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CHAPTER 2
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Once the correction changes are enabled, press the Enter button and the LD-3 changes how much correction is needed due to the throw of your M Series line or curvilinear array on the channel.

Insert Switch

Each output channel utilizes an Insert switch which allows you to add outboard signal processing such as parametric equalization. Figure 2.10 shows the Insert/Return Inputs, as well as the auxiliary output section (Sends), with a Meyer Sound CP-10 complementary phase parametric equalizer.
Figure 2.10. The LD-3’s back panel showing Sends and Returns for 1-3, A & B; a CP-10 can be added to the signal processing chain
CAUTION: The LD-3’s insert inputs are not
normalized; if the Insert switch is depressed with nothing connected, the channel will be effectively muted.

SUBS A AND B

Two subwoofer control sections (Figure 2.11) feature Polarity switches, Gain trim, illuminated Mute switches, Signal/Clip indicators, and Insert switches to accommodate outboard signal processing such as parametric equalization and/or delay.
Front Panel Rear Panel
Figure 2.11. The LD-3’s sub section
For each of the two Sub channels, these controls perform the following functions:
The Gain control sets the output level from –6 to +6 dB.
The illuminated Mute switch mutes the channel, ashing
red when muted.

Insert Inputs

The Insert/Returns — one for each Channel 1-3 (A and B — inputs are not affected by the setting of the High-Pass Filter (pre-HPF) but are affected by the settings of the Atmospheric Correction (post-atmospheric correction).

Send Outputs

The LD-3 features three Sends that are straightforward and are derived from three different places before the atmospheric correction (pre-atmospheric) in the signal path:
Full Range Pre-Array –The output signal is sent to your
outboard equipment without any array correction and no ltering.
Full Range Post-Array – The output signal is sent to
your outboard equipment with full array correction and no ltering.
Post-Array Post-HPF – The output signal is sent to
your outboard equipment with full array correction with the high pass lter for the master channel (A or B) on.
The bi-colored Signal/Clip LED indicates signal
presence and level with a variable intensity green color, and clipping with ashing red.
The blue illuminated Polarity switch allows you to
change polarity where as needed, according to the subwoofer you’re using and its interaction with the primary line or curvilinear array(s) in your design.
The Low Pass Filter switch employs a smooth, high-
quality elliptical lter at 55 or 80 Hz; the lter can be disabled by ipping the switch to “Off.”
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Insert Switch

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Each Sub channel utilizes an Insert switch (Figure 2.12) which, when engaged, is useful for driving a sub with a different send or output from a console, or other outboard equipment, if desired.
Figure 2.12. The LD-3’s Sub inserts
CHAPTER 2
CAUTION: The Sub section’s Insert inputs
are not normalized; if the Insert switch is depressed with nothing connected, the channel will be effectively muted.

Insert Inputs

The Insert/Returns are not affected by the array correction, but are affected by the Low-Pass Filter. The Sub section’s inserts have a summing stage. If not engaged, the LD-3 will sum the signal from the main input with the signal from the Insert input. This can be useful for making a mono sum left and right channels to drive the subs mono from the main inputs.
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CHAPTER 2
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CHAPTER 3: SYSTEM DESIGN, INTEGRATION, AND OPTIMIZATION

CHAPTER 3
The LD-3 opens up a number of design and integration scenarios. Its versatility, in conjunction with different M Series loudspeakers and/or subwoofers, gives you the freedom to not only plan for the atmospheric conditions and optimized the array, but to hone the design through quantitative Meyer Sound tools and software. This chapter will take you through some example congurations and introduce you to some real-world options for achieving your design quickly and efciently.

EXAMPLE DESIGN CONFIGURATIONS

The multiple input, output, insert/returns, and sends on the LD-3 makes the unit very versatile; it can accommodate a number of congurations to satisfy a wide number of applications. See Appendix B for three example congurations that demonstrate the exibility and utility of the LD-3.

MEYER SOUND MAPP ONLINE

To quantitatively plan your system design, Meyer Sound provides MAPP Online (Figure 3.1), a powerful, cross­platform, Java-based application for accurately predicting the coverage pattern, frequency response, impulse response, and maximum SPL output of single or arrayed Meyer Sound loudspeakers.
You can nd MAPP Online at:
www.meyersound.com/products/software/mapponline
NOTE: In order to use MAPP Online, you
will need to register by clicking “Apply for MAPP Online” on the Web page listed above. After registration and upon approval, an e-mail will be sent to you with a username and password along with the address for the Web page where you can download MAPP Online. Online instructions will guide you through the download and setup process.
As its name indicates, MAPP Online is an online application: when a prediction is requested, data is sent over the Internet to a high-powered server at Meyer Sound that runs a sophisticated acoustical prediction algorithm using high-resolution, complex (magnitude and phase) polar data. Predicted responses are returned over the Internet and displayed on your computer in color.
With MAPP Online, you can:
Plan an entire portable or xed loudspeaker system and
determine delay settings for ll loudspeakers.
Clearly see interactions among loudspeakers and
minimize destructive interference.
Place microphones anywhere in the sound eld and
predict the frequency response, impulse response, and sound pressure level at the microphone position using MAPP Online’s Virtual SIM feature.
Figure 3.1. MAPP Online is an intuitive, powerful system design tool.
Residing on your computer, MAPP Online facilitates conguring arrays of a wide variety of Meyer Sound products and, optionally, denes the environment in which they will operate, including air temperature, pressure, and humidity, as well as the location and composition of walls.
Rene your system design to provide the best coverage
of the intended audience area.
Use a virtual VX-1 program equalizer to predetermine
the correct control settings for best system response.
Gain valuable load information about the array to
determine rigging capacities.
MAPP Online enables you to come to an installation prepared with a wealth of information that ensures the system will satisfy your requirements “out of the box” – including basic system delay and equalization settings. Its accurate, high-resolution predictions eliminate unexpected onsite adjustments and coverage problems. With MAPP Online, every sound system installation has a maximum chance of success.
MAPP Online is compatible with Windows, Linux, Unix, and Apple Macintosh computers running Mac OS X version
10.1.2 or higher. The MAPP Online Web page above lists additional system requirements and recommendations.
13
CHAPTER 3
15
CHAPTER 3

LOUDSPEAKER/SUBWOOFER INTEGRATION

Using the LD-3’s lters helps to easily integrate and optimize your M Series arrays with subwoofers. High-pass lters augment array headroom by removing frequencies near the low end of the loudspeaker's operating range, while low-pass lters can remove unwanted mid-low frequencies reproduced by the subwoofers.
NOTE: Full-range signals may be applied to
Meyer Sound’s self-powered loudspeakers and subwoofers because they have built-in active crossovers. However, the use of external lters – like the ones in the LD-3 – is optional, and should be used very carefully to avoid phase shifts that can cause cancellations or dips in the response.
Table 3.1: MILO and M3D-Sub
HPF LPF ø Reverse Switch Result
80 80 Engaged Flat response
80 Off Engaged Flat response
160 Off Engaged Very at response
Off Off Off Boost in the 80 Hz
region
Table 3.2: MILO and 650-P (650-P set to pin 2 positive)
HPF LPF ø Reverse Switch Result
Off Off Engaged Boost in the 100 Hz
region
160 Off Engaged Very at response
80 80 Off Very at response
160 80 Off Flat response
Table 3.3: M3D and M3D-Sub
HPF LPF ø Reverse Switch Result
Off Off Off Flat response
80 Off Off Very at response,
+3 dB sub gain recommended
Table 3.4: M3D and 650-P
HPF LPF ø Reverse Switch Result
Off Off Engaged Flat response
Off 55 Engaged Flat response
80 55 Off Very at response,
+6 dB sub gain recommended
160 80 Off Very at response,
+6 dB sub gain recommended
The use of these lters reduces areas of overlap and minimizes the interaction and possible cancellations between subsystems, usually resulting in highly desirable behavior, such as very at frequency response. As shown in Tables 3.1 through 3.8, some of the loudspeaker and subwoofer combinations you can implement using the LD-3’s ltering capabilities can go a long way toward ne­tuning your system.
All data in Tables 3.1 through 3.8 are based on designs in a close-proximity, coplanar orientation, at a 2:1 ratio of loudspeakers to subwoofers. Out of all possible combinations, these yield the atest frequency response.
Table 3.5: M2D and M2D-Sub
HPF LPF ø Reverse Switch Result
Off Off Off Very at response
80 Off Off Very at response,
+3 dB sub gain recommended
80 80 Engaged Very at response,
+3 dB sub gain recommended
Table 3.6: M2D and 650-P (650-P set to pin 2 positive)
HPF LPF ø Reverse Switch Result
Off 55 Off Flat response, -
6 dB sub gain recommended*
80 80 Engaged Very at response,
-6 dB sub gain recommended*
* Unlike the matched sensitivity of the M2D and M2D-Sub, the 650-P is +6 dB more sensitive than the M2D/M2D-Sub.
Table 3.7: M1D and M1D-Sub
HPF LPF ø Reverse Switch Result
Off Off Off Very at response
80 80 Engaged Flat response,
+3 dB sub gain recommended
Table 3.8: M1D and USW-1P
HPF LPF ø Reverse Switch Result
Off 55 Off Flat response, -
6 dB sub gain recommended*
80 80 Engaged Very at response,
-6 dB sub gain recommended*
14
CHAPTER 3
NOTE: When loudspeakers and subwoofers
are physically separated by more than 4 feet – or delay must be used between them – a measurement system such as SIM (covered in the next section) should be used to determine the correct delay and polarity.

SIM® MEASUREMENT SYSTEM

Meyer Sound also offers a self-contained design and troubleshooting package: the SIM Measurement System. SIM is a measurement and instrumentation system including a selection of hardware and software options, microphones and accessory cables. SIM is optimized for making audio frequency measurements of an acoustical system with a resolution of up to 1/24th of an octave; the high resolution enables you to apply precise electronic corrections to adjust system response using frequency and phase (time) domain information.

Source Independent Measurement Technique

Applications

The main application of SIM is loudspeaker system testing and alignment. This includes:
Measuring propagation delay between the subsystems
to set correct polarities and set very precise delay times
Measuring variations in frequency response caused
by the acoustical environment and the placement and interaction of the loudspeakers to set corrective equalization
Optimizing subwoofer integration
Optimizing loudspeaker arrays
SIM can also be used in the following applications:
Microphone calibration and equalization
Architectural acoustics
Transducer evaluation and correction
Echo detection and analysis
Vibration analysis
Underwater acoustics
SIM implements the Meyer Sound source independent measurement technique, a dual-channel method that accommodates statistically unpredictable excitation signals. Any excitation signal that encompasses the frequency range of interest (even intermittently) may be used to obtain highly accurate measurements of acoustical or electronic systems. For example, concert halls and loudspeaker systems may be characterized during a musical performance using the program as the test signal, allowing you to:
View measurement data as amplitude versus time
(impulse response) or amplitude and phase versus frequency (frequency response)
Utilize a single-channel spectrum mode
View frequency domain data with a logarithmic
frequency axis
Determine and internally compensate for propagation
delays using SIM Delay Finder function
15
CHAPTER 3
16
17
APPENDIX A
ATMOSPHERIC CORRECTION (Affects Output Channels 1-3, both A & B)
Temperature
Altitude
ARRAY CORRECTION
Type
Array Size
Attenuation Control
Attenuation Control
Toggles the polarity of the sub output
Attenuation Control
Toggles the input from Master to Insert/Return. Not normalized, mutes channel when
AUDIO INPUTS
Type
differential (between pins 2 and 3)
Ratio
Threshold: -26 dBV (50 mV rms) pink noise or sinewave
APPENDIX A

APPENDIX A

Insert/Return
AUDIO OUTPUTS
Type
balanced (between pins 2 and 3)
Load: ±17.8 V pk (+22 dBV, +24.2 dBu sinewave) No Load: ±19 V pk (+22.5 dBV,
0 dBV = 1 V rms; 0 dBu = 0.775 V rms; 0 dBm = 1 mW rms.
)
AUDIO PERFORMANCE
Ratio of maximum sinewave to A-weighted noise  oor.
THD
AC POWER

APPENDIX B

Left
Right
LD-3
Channel A
IN SUB OUT
CH 1 OUT
CH 2 OUT
CH 3 OUT
Channel B
IN SUB OUT
CH 1 OUT
CH 2 OUT
CH 3 OUT
Channel A
INSERTS SENDS
IN SUB OUT
Full Range
IN CH 1 OUT
Post Array
IN CH 2 OUT
Post Array
IN CH 3
Post HPF
Channel B
INSERTS SENDS
IN SUB OUT
Full Range
IN CH 1 OUT
Post Array
IN CH 2 OUT
Post Array
IN CH 3
Post HPF
Example Configurations
APPENDIX B
19
APPENDIX B
21
APPENDIX B
Left
Right
LD-3
Channel A
IN SUB OUT
CH 1 OUT
CH 2 OUT
CH 3 OUT
Channel B
IN SUB OUT
CH 1 OUT
CH 2 OUT
CH 3 OUT
Channel A
INSERTS SENDS
IN SUB OUT
Full Range
IN CH 1 OUT
Post Array
IN CH 2 OUT
Post Array
IN CH 3
Post HPF
Channel B
INSERTS SENDS
IN SUB OUT
Full Range
IN CH 1 OUT
Post Array
IN CH 2 OUT
Post Array
IN CH 3
Post HPF
20
APPENDIX B
DigitalDelay
2 In x 6 Out
Digital Delay/EQ
LD-3
Channel A
IN SUB OUT
CH 1 OUT
CH 2 OUT
CH 3 OUT
Channel B
IN SUB OUT
CH 1 OUT
CH 2 OUT
CH 3 OUT
Channel A
INSERTS SENDS
IN SUB OUT
Full Range
IN CH 1 OUT
Post Array
IN CH 2 OUT
Post Array
IN CH 3
Post HPF
Channel B
INSERTS SENDS
IN SUB OUT
Full Range
IN CH 1 OUT
Post Array
IN CH 2 OUT
Post Array
IN CH 3
Post HPF
Main Left
Right
Subwoofer Mono
(10) MILO
(10) MILO
21

APPENDIX C

3
2
1
ESD
Absorber
ESD
Absorber
RF Filter
10k
-12 to +6dB
MASTER
LEVEL
ARRAY SIZE
CORRECTION
Signal & Cl ip
Detector
-
+
ESD
Absorbers
3
2
1
POWER
OFF MUTE
(SHORT)
PUSH-PULL
DRIVER
GREEN / RED
LED
3
2
1
ESD
Absorbers
ESD
Absorbers
RF Filter
-
+
ESD
Absorbers
3
2
1
POWER
OFF MUTE
(SHORT)
PUSH-PULL
Serial Data Port
(Remote Download)
DRIVER
80 Hz
160 Hz
PUSH-PULL
DRIVER
OFF
80 Hz
160 Hz
CH 1-3
CROSSOVER
80 Hz
55 Hz
OFF
80 Hz
55 Hz
SUB
CROSSOVER
SUB
POLARITY SWITCH
SUMMING
STAGE
IN OUT
SUB
INSERT
LED
ENTER
M1D
M2D MILO
M3D
# OF SPEAKER S SPKR MODEL
-
INVERTER
-180°
MICRO
PROCESSOR
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
SEND 1
Full Range Pre-Array C orrection
SUB
INPUT / INS ERT
(PRE LPF)
MAIN
INPUT
SEND 2
Full Range Post-Array Correction
-
+
G
-
+
G
-
+
G
-
+
G
GREEN /
RED
CHANNEL 1
INSERT
CHANNEL 2
INSERT
CHANNEL 3
INSERT
PRE-ATMOSPHERIC
POST HPF
PRE-ATMOSPHERIC
POST HPF
ATMOSPHERIC
POST HPF
S
APPENDIX C
LD-3 Signal Flow Diagram
22
APPENDIX C
-
+
ESD
Absorber
3
2
1
POWER
OFF MUTE
(SHORT)
PUSH-PULL
DRIVER
3
2
1
ESD
Absorber
ESD
Absorbers
RF Filter
3
2
1
ESD
Absorber
ESD
Absorbers
RF Filter
DIFFERENTIAL AMPLIFIER
DIFFERENTIAL AMPLIFIER
3
2
1
ESD
Absorber
ESD
Absorbers
RF Filter
DIFFERENTIAL AMPLIFIER
INSERT SWITCH
INSERT SWITCH
ATMOSPHERIC
CORRECTION
INSERT SWITCH
MAX
CORRECTION
LED
LED
GREEN / RED
LED
GREEN / RED
YELLOW
YELLOW
YELLOW
LED
GREEN / RED
LED
GREEN / RED
ATMOSPHERIC
CORRECTION
MAX
CORRECTION
LED
ATMOSPHERIC
CORRECTION
MAX
CORRECTION
LED
LED
ENTER
SIGNAL &
CLIP
DETECTOR
-6 TO +6 dB
-
+
ESD
Absorber
3
2
1
POWER
OFF MUTE
PUSH-PULL
DRIVER
CHANNEL 1
LEVEL
SIGNAL &
CLIP
DETECTOR
-6 TO +6 dB
-
+
ESD
Absorber
3
2
1
POWER
OFF MUTE
PUSH-PULL
DRIVER
CHANNEL 2
LEVEL
SIGNAL &
CLIP
DETECTOR
-6 TO +6 dB
-
+
ESD
Absorber
3
2
1
POWER
OFF MUTE
PUSH-PULL
DRIVER
CHANNEL 3
LEVEL
SIGNAL &
CLIP
DETECTOR
-6 TO +6 dB
-
+
ESD
Absorber
3
2
1
POWER
OFF MUTE
PUSH-PULL
DRIVER
SUB
LEVEL
MASTER
MUTE
CONTROL
MUTE
MUTE
MUTE
MUTE
TEMP. H UM.
PRES
SW.
CH. 1 CH. 2 CH. 3
DISTANCE
MICRO PROCESSOR
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
EARTH GND/ CHASSIS
SEND 3
Post HPF X-Over Post Array Correction
-
+
G
-
+
G
-
+
G
-
+
G
GREEN /
RED
-
+
G
-
+
G
-
+
G
-
+
G
CHANNEL 1
INSERT
CHANNEL 2
INSERT
CHANNEL 3
INSERT
CHANNEL 1 OUT
CHANNEL 2 OUT
CHANNEL 3 OUT
SUB OUT
PRE-ATMOSPHERIC
POST HPF
PRE-ATMOSPHERIC
POST HPF
PRE-
ATMOSPHERIC
POST HPF
23
APPENDIX C
24
Meyer Sound Laboratories Inc. 2832 San Pablo Avenue Berkeley, CA 94702 USA
T: +1 510 486.1166 F: +1 510 486.8356 techsupport@meyersound.com www.meyersound.com
Meyer Sound Laboratories Inc.
© 2003
All Rights Reserved
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