Listen Technologies LA-350 Guide

Dear Valued Customer,
Thank you for choosing Listen! All of us at Listen are dedicated to provide you
with the highest quality products available. We take great pride in their
outstanding performance because we care that you are completely
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standards and back them with a limited lifetime guarantee. We stand ready
to answer any questions you might have during installation or in the operation
of our products. Should you experience any problems whatsoever with your
Listen products, we are ready to help you in any way we can with prompt,
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have any comments on how we might improve our products or our
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+1.801.233.8992
+1.800.330.0891 North America
+1.801.233.8995 Fax
[email protected]
www.listentech.com
Thank you and enjoy your listening experience!
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Russell Gentner and the Listen Team
• In the few instances where repairs were needed, 99% of all clients indicated that they were happy
with repair turn-around-times and 85% of the time, clients were without their product for less than
10 days!
• Overall client satisfaction of working with Listen was rated 4.8 out of 5.
• “Please continue with your excellent attitude toward customer satisfaction. You guys are great!”
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• “You stand behind your product wonderfully.”
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LR-42/44
Design Guide LT-82 LA-140 LR-42/44 LA-350/351 Supplementary Design Guide LT-82 LA-140 Supplementary
LR-42/44 LA-350/351
Design Guide
Infrared Technology Overview 5
System Overview 6
Designing a System 9
DesignTools 21
LT-82 Stationary IR Transmitter
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Quick Reference Page 37
Setup and Operating Instructions 38
Accessories for LT-82 43
LA-140 IR Radiator
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Quick Reference Page 54
Setup Instructions 55
LEDIndications 57
Mounting your Radiator 58
Accessories for LA-140 78
LR-42/LR-44 4-Channel IR Receivers
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LR-42 Quick Reference Page 89
LR-44 Quick Reference Page 90
Setup Instructions 91
Operating Instructions 95
Locking Instructions 101
Programming Instructions 102
Programming Examples 107
Programmable Features Detailed Descriptions 110
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Accessories for LR-42/LR-44 115
LA-350/LA-351 8-Unit IR Receiver Storage/Charging Cases
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LA-350 Charging Requirements/Instructions 125
CordTidyRack 128
Supplementary Information
Troubleshooting 137
Frequently Asked Questions 139
Compliance Information 141
Warranty 141
Contacting Listen 141
Stationary Infrared Table of Contents

Design Guide Design Guide
Stationary Infrared Design Guide Table of Contents
Infrared Technology Overview 5
SystemOverview 6
Designing a System 9
DesignTools 21

Design Guide
Design Guide Design Guide

5
Design Guide Design Guide
Infrared Technology Overview
Infrared or “IR” technology uses infrared light to transmit audio without wires. This type of transmission is
advantageous to RF transmission because it is secure, it is not susceptible to RF interference, and one receiver
can be used for multiple rooms within a facility. The transmitter accepts an audio signal and then frequency
modulates an RF carrier at 2.3, 2.8, 3.3 and/or 3.8MHz. This carrier along with DC power (to power the
radiator) is supplied to the radiator via cables. The carriers are then radiated into the room using IR emitter
diodes. This is the same technology used by the remote control of your TV set. A receiver then receives the IR
light and demodulates the carrier.
123
4
Audio Source
IR Transmitter
Radiator
Receiver
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a facility so users will not have drop outs of the IR signal. This design guide will help you do this.
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achieve greater coverage. For example, when emitting in a very large room (like an exhibit hall) you will
notice that you need to point the receiver directly at the radiator to pick up the signal. However, when
the radiator is placed in a smaller room (for example 50 ft2/14.6 m2square) with white walls you will
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directions, increasing coverage.
• Listen systems use higher modulation frequencies that make the system less susceptible to light
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interference from sources that create IR light such as sunlight and plasma displays.
• Listen products are compatible with other manufacturers who use the same modulation frequencies
(2.3, 2.8, 3.3, 3.8 MHz).

6
Design Guide
Design Guide Design Guide
System Overview
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ers.
A single channel system consists of one LT-82 transmitter and one or more radiators. The diagram below shows
such a system with one radiator. The radiator is powered from the power supply at the transmitter. This power
supply can supply enough power for the LT-82 and up to two LA-140 radiators. If you need more than two
radiators, you will need more power supplies. This is discussed later in this document. Power is supplied from
standard CAT-5 cable while RF from the transmitter is delivered using 50-ohm RG-58 coaxial cable. The radiator
is supplied with 25 feet (7.6 meters) of CAT-5 and RG-58 coaxial cable.
Single Channel System
LT-82 Stationary IR Transmitter
Mounting hardware for
radiator included with
radiator
RF – RG-58 50 ohm Cable
LR-42 IR Stetho Receiver
LR-44 IR Lanyard Receiver
Power – CAT-5 Cable
LA-140 IR Radiator
IR
123
4
123
4
123
4
LT-82 Transmitter
LA-140 Radiator
LR-42 LR-44
123
4

7
Design Guide
Design Guide Design Guide
System Overview
A multiple channel system consists of two to four LT-82 transmitters and one or more radiators. The diagram
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transmitter. This power supply can supply enough power for the LT-82 and two LA-140 radiators. If you need
more than two radiators, you can use the power from the other transmitters. In this example, the four
transmitter power supplies can supply enough power for up to eight LA-140 radiators. This is discussed later in
this document. Power issupplied from standard CAT-5 cable while RF from the transmitter is delivered using
50-ohm RG-58 coaxial cable. Each radiator is supplied with 25 feet (7.6 meters) of CAT-5 and RG-58 coaxial
cable.
Multiple Channel System
Up to four LT-82 transmitters can
be daisy chained together (using
RG-58 cable) to create a
multi-channel system
LA -89 RG-58 Multi-carrier
Interconnection Cable (included)
RF – RG-58 50 ohm Cable
RF – RG-58 50 ohm Cable
Up to 100 LA-140 radiators can be daisy chained
together (using RG-58 cable) to provide sucient
IR power for most applications
LR-42 IR Stetho Receiver
LR-44 IR Lanyard Receiver
Radiator Power: Radiators can be
powered from the LT-82 (up to two
radiators) or an additional power supply
(LA-205) can power up to two radiators
Radiator RF: RF from the last LT-82 must be
daisy chained from radiator to radiator
Power – CAT-5 Cable
Power – CAT-5 Cable
LA-140 IR Radiator
LA-140 IR Radiator
IR
IR
LT-82 Stationary IR Transmitter
LT-82 Stationary IR Transmitter
LT-82 Stationary IR Transmitter
LT-82 Stationary IR Transmitter
123
4
123
4

8
Design Guide
Design Guide Design Guide
System Overview
Each LT-82 transmitter used can power up to two LA-140 radiators. If you design a system that requires more
radiators than the transmitters can power, you need to order additional LA-205 power supplies. Each LA-205
can power up to two LA-140 Radiators.
Key Concepts of Designing a Stationary IR System
1Each LT-82 transmitter used can power two LA-140 radiators
Up to four LT-82 transmitters can be interconnected to create up to a four channel system. For the system,
there are two RF outputs provided for connection to the radiators. Each of these two outputs is referred to as
the “Radiator Daisy Chain.” RG-58 coaxial cable is used to interconnect the RF in the radiator daisy chain. You
can connect as many radiators in the daisy chain as you need.
2Up to four LT-82 transmitters can be interconnected to create up to a four channel system
Each radiator requires one RF (RG-58 coax) connection and one power (CAT-5) connection. The RF
connection can come from a transmitter or from another radiator. The power connection can come from
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3Each radiator requires one RF (RG-58 coax) connection and one power (CAT-5) connection
To make it easy for you to design, specify and install a system, Listen has provided mounting hardware for
most mounting situations including wall, ceiling, corner, desk, tripod and mic stands. To double the radiation
power you can vertically or horizontally mount two radiators together using the LA-342 dual radiator mounting
brackets. This includes coaxial RF and CAT-5 power cables.
4Listen has provided mounting hardware for most LA-140 mounting situations
Due to the higher modulation frequencies, it is possible that the RF signal arrives to different radiators at
different times. This delay can cause the IR carriers to add “out of phase” and cause the signal to drop
out. To solve this problem, Listen has provided a delay compensation adjustment on each radiator.
This design guide will help you calculate the setting for this adjustment.
5It is possible that the RF signal arrives to dierent radiators at dierent times
As the number of channels increases, the effective radiated coverage declines. For example, a two
channel system will have half the coverage of a single channel system. If is important to increase the
number of radiators for multiple channel systems.
6As the number of channels increases, the eective radiated coverage declines
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addition, the radiator has been under-rated to account for system degradation as the IR emitting LEDs
age over time. It is important to design the system based on these coverage patterns and not by trial
and error. The reason for this is that the coverage pattern will be stronger when the radiator is new.
A system that has adequate coverage today may not have adequate coverage in the future if not
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7The coverage patterns provide coverage of the system assuming no reection
CAT-5 power cable should never exceed 1000 feet from the source power supply.
8The maximum length of CAT-5 power cable
NOTE: Adding additional transmitters will decrease radiator coverage.
Coaxial RF signal cable should never exceed 1000 feet from the source transmitter.
9The maximum length of coaxial RF cable

9
Design Guide
Design Guide Design Guide
Designing a System
You will need to order one LT-82 transmitter for each audio channel. The Listen system can deliver up to four
audio channels simultaneously.
1Determine the number of audio channels
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2Determine the room size and shape
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transmitters, power supplies and radiators using the worksheet key. The following factors will determine the
coverage of the room.
3Complete the room layout worksheet
3A Except in small rooms it is recommended that at least two radiators be used to ensure good coverage and
minimal shading. Listen radiators (when used with Listen receivers) will cover approximately 10,000 ft2
(929 m2) for one channel as indicated in the diagram below (note the coverage decreases as the number
of channels goes up). For two channels, one radiator will cover 5,000 ft2(465 m2) and for four channels, one
radiator will cover 2,500 ft2(232 m2).
Number of radiators and location
You should use the above coverage pattern to determine coverage of each radiator in your system, not
by trial and error. The radiator will be stronger when new and therefore is under-rated by 40 percent and
the coverage pattern above accounts for this. 40 percent degradation will occur after approximately 8,000
operating hours.
10
10
0
0
30
20
50
40
40
50
20
30
10
20 30 40 50 60 70 80 90 100 110 120 130 140 150
1 TX2 TX4 TX
Horizontal Plane Footprint Pattern (feet)
Coverage pattern
shown in feet

10
Design Guide
Design Guide Design Guide
Designing a System
Horizontal Polar Pattern
Vertical Polar Pattern
Single Channel System
Single Channel System

11
Design Guide
Design Guide Design Guide
Designing a System
In this example a total of four radiators, one in each corner, ensures good coverage at all locations and orientations.
Except in small rooms, it is recommended that at least two radiators are used to prevent shading of the IR signal.
It is a good idea to provide over-lapping coverage (like in a sprinkling system) of the signal whenever possible to ensure that
the signal does not have drop outs. In addition, you should provide special radiator coverage for shaded areas such as under
a balcony or in the front of a room where the front mounted radiators do not provide enough coverage.
The following diagrams illustrate these concepts.

12
Design Guide
Design Guide Design Guide
Designing a System
If there is an area within a room (such as under a balcony) that is shielded
from the main radiation pattern, you will need to provide additional
radiator(s) to cover this area.

13
Design Guide
Design Guide Design Guide
Designing a System
To double the radiator power, it is possible to vertically or horizontally mount two radiators together using the
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RAD 1
RAD 2
3B It is critical to mount the radiators at the proper height. If the radiator is mounted too low, the coverage
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required angle of the radiator will cause the radiation pattern to be compromised. The best height of the
radiator is about 16 ft2(5 m2IURPWKHÁRRU
Height of Radiators
3C The mounting system for Listen LA-140 radiators allow you to mount the radiator in 15 degree increments.
The best angle depends on the shape of the room and the orientation of the radiator to the seats within the
room. In general, mounting angles of 15 and 30 degrees provide the best coverage.
Radiator Mounting Angle

14
Design Guide
Design Guide Design Guide
Designing a System
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is recommended that you draw the room out indicating the location of each radiator in the room and cable
runs from the transmitter(s) and power supplies (if any) to the radiator. We have provided the room layout
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4Determine the number of radiators required