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.

Manufacturer's Address:

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: [phone] Fax: [phone]

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

!

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: [phone]

Fax: [phone]

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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