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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


Frequency Response63 Hz - 15 kHz (+/- 3 dB)
Signal-to-Noise RatioMono: > 60 dBStereo: > 52 dB
System Distortion< 2% total harmonic distortion (THD)
Audio Input 1Mono 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 2Stereo or Mono Input (Rear Panel). Two (2) Phono connectors, unbalanced, -10/+10 dBu nominal input level adjustable, +30 dBu maximum, impedance 100k
Audio ProcessingCompression can be turned on/off.
ContourCuts and boosts frequencies above 5 kHz
Monitor OutputFront 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/sInput 1 and Input 2 Mixed Output (Rear panel). Two (2) Phono connectors, unbalanced, -10 dBu nominal output level, +19 dBu maximum, impedance 10 ohms


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


LCDChannel designation, lock status, RF Carrier, programming (front panel)
Unit PowerRed LED illuminates when the unit is powered up (front panel)
Input 1, Input 2, Transmit LevelIndicates Input 1, Input 2, and Transmit audio levels. 10 segment LED's (8 green, 2 red)
StereoIndicated by a green LED when on (front panel)
ProcessingIndicated by a green LED when on (front panel)
RF CarrierIndicates carrier is active on the LCD Display (front panel)
Test ToneRed LED illuminates when test tone enabled (front panel)


Input/sOne (1) BNC connector, for connection from additional transmitter(s). 50 mV, 50 ohm, -15 dBm
Output/sTwo (2) BNC connectors, for connection to radiator(s) and/or additional transmitter(s). 50 mV, 50 ohm, -15 dBm
Carrier Frequencies2.3 MHz, 2.8 MHz, 3.3 MHz, 3.8 MHz
Number of ChannelsFour (4) channels. Selectable one (1) channel per transmitter (mono or stereo)
Frequency Accuracy+/- .005% stability 0 to 50 °C
Carrier Shut OffCarrier will shut off when no audio is present for 30 minutes to preserve radiator life.
Transmitter Stability50 PPM


Power SupplyIn-line switching mode power supply, Listen part number LA-205
Power Supply Input100-240 VAC, 47-63 Hz
Power Supply Output30 VDC, 1.5 A
Power Supply ConnectorRJ-45
Power OutputTwo (2) RJ-45 jacks. For remote powering up to two (2) radiators


Width8.50 in. (21.5 cm)
Height1.75 in. (4.5 cm)
Depth9.13 in. (23 cm)
ColorDark Grey
Unit Weight with Power Supply3.8 lbs. (1.72 kg)
Shipping Weight6.0 lbs. (2.7 kg)
Rack MountingOne (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.
Weight2.6 lbs. (1.18 kg)
Power Line CordNorth America, Type B, (LT-82-01)Asia, UK, Type G, (LT-82-02)Euro Type J, (LT-82-03)


Temperature - Operation14 °F (-10 °C) to +104 °F (40 °C)
Temperature - Storage-4 °F (-20 °C) to +122 °F (50 °C)
Relative Humidity0 to 95% relative humidity, non-condensing


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