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The heart of the Listen Technologies ListenIR system is the LT-82 single-channel transmitter. Capable of operating in either mono or stereo modes, the LT-82 transmits your audio signal to and provides DC power for one or more LA-140 infrared radiator/emitter units through a standard CAT-5 cable. Plus, units can be combined to offer up to four (4) channels of mono or stereo audio for expanded applications.

The LT-82 transmitter is an ideal infrared transmitter for a wide range of assistive listening needs, including theaters, houses of worship, language interpretation, and more.


One (1) LT-82 ListenIR 1-Channel Transmitter
One (1) LA-205 30 VDC Extension/Replacement Power Supply for LA-140/LT-82
One (1) LA-89 Interconnection Coaxial Cable
One (1) Quick Reference Card


  • Expandable and affordable transmitter unit for infrared assistive listening systems
  • Provides DC power for up to two (2) LA-140 radiator/emitter units via standard CAT-5 cabling
  • Audio signal is provided to the LA-140 radiator/emitter units via RG-58 coaxial cable
  • Transmits up to four (4) channels of mono or stereo audio (one channel per LT-82 unit)
  • Crystal-clear and secure audio performance for venues, houses of worship, meetings, conference rooms, and more
Configurations & Architectural Specs


LT-82-01 Stationary IR Transmitter (North America)*
LT-82-02 Stationary IR Transmitter (Asia, UK)*
LT-82-03 Stationary IR Transmitter (Euro)*
LT-82-04 Stationary IR Transmitter (Australia)*
*01, 02, 03, and 04 designation refers to international plug type (type B, G, C, and I) for the power supply.

Architectural Specs

The Stationary IR Transmitter shall be capable of broadcasting on four (4) mono or stereo carriers; 2.3, 2.8, 3.3 and 3.8 MHz. Channel Selection shall be capable of being locked. Multiple transmitters shall be capable of being daisy-chained together to transmit up to four (4) channels simultaneously. The transmitter shall have a timer that shuts off the carriers after 30 minutes when no audio is present at the transmitter. The transmitter shall have a SNR of 60 dB or better. The device shall have an audio frequency response of 63 Hz to 15 kHz, +/- 3db. It shall have two (2) mixing audio inputs, one (1) balanced XLR/phone input and one (1) unbalanced RCA input. The device shall have the following audio controls:input level, transmit level, contour level and stereo on/off control. The device shall have an audio processor that is capable of automatic gain control and limiting. The transmitter shall provide power for up to two (2) radiators over CAT-5 cable. The LT-82 is specified.

Product Specifications
Specification LT-82


Frequency Response 63 Hz - 15 kHz (+/- 3 dB)
Signal-to-Noise Ratio Mono: > 60 dBStereo: > 52 dB
System Distortion < 2% total harmonic distortion (THD)
Audio Input 1 Mono Input (Rear Panel). Female-XLR and 1/4 in. combo connector, balanced, 0/-55 dBu (line/mic) nominal input level adjustable; +21/-30 dBu (line/mic) maximum input level; impedance 20k/1k ohms (line/mic); phantom power +12 VDC
Audio Input 2 Stereo or Mono Input (Rear Panel). Two (2) Phono connectors, unbalanced, -10/+10 dBu nominal input level adjustable, +30 dBu maximum, impedance 100k
Audio Processing Compression can be turned on/off.
Contour Cuts and boosts frequencies above 5 kHz
Monitor Output Front panel. One (1) 3.5 mm (0.14 in.) connector, unbalanced, adjustable output level, +7 dBu maximum, impedance 10 ohms. 100 mW, 32 ohms
Output/s Input 1 and Input 2 Mixed Output (Rear panel). Two (2) Phono connectors, unbalanced, -10 dBu nominal output level, +19 dBu maximum, impedance 10 ohms


Programming Stereo on/off, Processing on/off
Front Panel Power, Test Tone on/off, Channel up/down, Input Level, Transmit Level, Contour, Monitor Level
Rear Panel Input 1 Level (Line, Mic, Mic-Phantom Power), Input 2 Level (-10/+10 dBu)
Internal Adjustments Compression ratio for audio processor. Slope adjustable from 1:1 to 4:1. Default 2:1


LCD Channel designation, lock status, RF Carrier, programming (front panel)
Unit Power Red LED illuminates when the unit is powered up (front panel)
Input 1, Input 2, Transmit Level Indicates Input 1, Input 2, and Transmit audio levels. 10 segment LED's (8 green, 2 red)
Stereo Indicated by a green LED when on (front panel)
Processing Indicated by a green LED when on (front panel)
RF Carrier Indicates carrier is active on the LCD Display (front panel)
Test Tone Red LED illuminates when test tone enabled (front panel)


Input/s One (1) BNC connector, for connection from additional transmitter(s). 50 mV, 50 ohm, -15 dBm
Output/s Two (2) BNC connectors, for connection to radiator(s) and/or additional transmitter(s). 50 mV, 50 ohm, -15 dBm
Carrier Frequencies 2.3 MHz, 2.8 MHz, 3.3 MHz, 3.8 MHz
Number of Channels Four (4) channels. Selectable one (1) channel per transmitter (mono or stereo)
Frequency Accuracy +/- .005% stability 0 to 50 °C
Carrier Shut Off Carrier will shut off when no audio is present for 30 minutes to preserve radiator life.
Transmitter Stability 50 PPM


Power Supply In-line switching mode power supply, Listen part number LA-205
Power Supply Input 100-240 VAC, 47-63 Hz
Power Supply Output 30 VDC, 1.5 A
Power Supply Connector RJ-45
Power Output Two (2) RJ-45 jacks. For remote powering up to two (2) radiators


Width 8.50 in. (21.5 cm)
Height 1.75 in. (4.5 cm)
Depth 9.13 in. (23 cm)
Color Dark Grey
Unit Weight with Power Supply 3.8 lbs. (1.72 kg)
Shipping Weight 6.0 lbs. (2.7 kg)
Rack Mounting One (1) rack space high (1U), 1/2 rack space wide. One (1) or two (2) transmitters can be mounted in a single rack space. Optional Rack mount (LA-326) not included.
Weight 2.6 lbs. (1.18 kg)
Power Line Cord North America, Type B, (LT-82-01)Asia, UK, Type G, (LT-82-02)Euro Type J, (LT-82-03)


Temperature - Operation 14 °F (-10 °C) to +104 °F (40 °C)
Temperature - Storage -4 °F (-20 °C) to +122 °F (50 °C)
Relative Humidity 0 to 95% relative humidity, non-condensing


Standards FCC Part 15, Industry Canada, CE, RoHS, UL
Used With
Q How many carriers does the LT-82 produce?
A One.
Q How do you interconnect multiple LT-82 units?
A Units are daisy chained using a short piece of coax cable (supplied with each LT-82).
Q How many radiators does the LT-82 power?
A The LT-82 powers up to two (2) Listen LA-140 radiators.
Q Can I use the LT-82 with other manufacturer's radiators?
A Yes, but the LT-82 will not power those radiators.
Q Can the LT-82 be operated on 230 VAC?
A Yes, the LT-82 has a universal power supply that can be used anywhere in the world.
Q Is there any performance degradation in stereo mode?
A Yes, stereo operation raises the noise floor slightly.
Q Can I operate some channels in mono and others in stereo?
A Yes.
Q How many carriers can be produced simultaneously in a room?
A Four. You will need one LT-82 Stationary IR Transmitter per carrier.
Q How are radiators connected to the LT-82?
A The carrier (signal) is connected using coax cable; power is connected using standard CAT-5 cabling.
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