Listen Technologies LT-84
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Listen Technologies LT-84

The Listen Technologies LT-84 ListenIR 2-channel infrared transmitter-radiator provides a cost effective and easy-to-use assistive listening solution. This high power combination unit provides coverage of up to 2,787m² (30,000ft²).

This signal range ensures that users in any mid-sized space, from the boardroom to the courtroom and beyond, enjoy an uninterrupted audio performance.

Constructed from infrared transparent material and without any controls on the front to maximise transmission.

One LT-84 can be used with up to four expansion radiators (LA-141), to offer additional coverage (when mounted within 30.48 m [100 ft.] from the unit). Delay compensation circuitry ensures that there are no signal cancellation dropouts. 

Additionally, the LT-84 can transmit on up to four different frequencies (2.3 MHz, 2.8 MHz, 3.3 MHz, or 3.8 MHz). This flexibility makes setup and operation even easier, without needing purchase separate, frequency-specific transmitter-radiator units.

  • Affordable, effective, and expandable solution ideal for small to mid-size spaces such as classrooms, courtrooms, boardrooms etc
  • Multiple frequency options for flexibility and simplicity during installation and setup
  • Offers gapless coverage up to 2,787 square meters (30,000 square feet)
  • Up to four (4) LA-141 expansion radiators can be added for additional coverage area
  • Single CAT-5e cable carries both power and signal to LA-141 expansion radiators
  • Multiple input options for easier setup and operation


Each LA-141 Expansion Radiator is supplied with:
One (1) 25 ft. (7.6 m) CAT-5e Cable
One (1) LA-344 Flexible Mounting Hardware
One (1) Quick Start Guide

List Ex VAT: £673.60
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Frequency Response

20 Hz - 20 kHz (+/- 1 dB) Line Input63 Hz - 15 kHz (+/- 3 dB) System Specification (wireless end-to-end with LR-44)

Signal-to-Noise Ratio

> 70 dB (SNR) Line Input> 60 dB (SNR) System Specification (wireless end-to-end with LR-44)

Microphone Input

Two (2) 3.5 mm (0.14 in.) Tip/Sleeve connector, -30 dBu nominal input, +14 dB headroom, impedance 4.4k Ohms, 5 VDC bias supply

Total Harmonic Distortion

< 0.1% (THD) Line Input< 2% (THD) System Specification (wireless end-to-end with LR-44)

Unbalanced Line Input

Stereo/Mono Input. Two (2) Dual (RCA) Phono connectors, unbalanced, -10 dBu nominal input, +14 dB headroom, impedance 10k Ohms

Balanced Line Input

Mono Input. Two (2) Phoenix Type connector, balanced, + 4 dBu nominal input, +14 dB headroom, impedance 100k Ohms



Power Switch

Three (3) position switch - Power OFF, Power ON-Indicator Lights OFF, Power ON-Indicator Lights ON

Carrier Frequency Selection

Two (2), four (4) position rotary switches (2.3 MHz, 2.8 MHz, 3.3 MHz, 3.8 MHz)

Level Control Knob

Two (2) audio taper rotary potentiometer, counter-clockwise decreases input mix level, clockwise increases input mix level



Power Supply LED

Green LED on in-line power supply indicates AC power is applied

Audio Level Indicators

Two (2) green LEDs indicates audio presence, two (2) red LEDs indicates peaks in the audio 

RJ-45 Amber LED

Solid Amber: carrier is present and IR is being transmitted

RJ-45 Green LED

Solid Green: power applied to unit / Flashing Green: unit has entered power save mode



Carrier Frequencies

2.3 MHz, 2.8 MHz, 3.3 MHz, 3.8 MHz, Selectable

Number of Channels

Two (2) channels, Selectable carrier frequency

Frequency Accuracy

+/- .005% stability 0 to 50 °C

Transmitter Stability

50 PPM


FM Wideband, ±50kHz deviation max, 50 ?S pre-emphasis

Power Save Mode

Carrier will shut off when no audio is present for 15 minutes on both channels to preserve radiator life

Expansion Link Output

Two (2) RJ-45 connectors - Provides RF Signal and Power, CAT-5e cable 24 AWG, 100 ft. maximum cable length, two (2) LA-141s per output connector



Coverage Area

2,787 m² (30,000 ft²) single channel with LR-4200-IR/LR-5200-IR receivers or 697 m² (7,500 ft²) single channel with LR-42/LR-44 receivers

IR Emitter Power

1.49 W



Power Supply Input

100-240 VAC, 50-60 Hz

Power Supply Output

12 VDC, 4 A, 48 W

Power Supply Connector

2.5 mm ID barrel connector, center positive

Power Output

Two (2) RJ-45 connectors. providing Power and RF signal for up to two (2) LA-141 expansion radiators on each output

Power Supply Type

In-line switching mode power supply, Listen part number LA-210

Power Supply 

UK type IEC line cord, (LT-84-02version)




Black with White Silk Screening

Unit Weight / Shipping Weight

1.8 lbs. (0.8 kg) / 3.4 lbs. (1.54 kg) with Power Supply


Can be mounted on a wall, ceiling, or table with provided hardware (screws and hollow wall anchors not provided). Optional LA-347 Wall Box Mounting Plate is available for mounting to a standard single gang electrical box.

Dimensions (H x W x D)

1.5 x 10.7 x 4.1 in. (3.81 x 27.2 x 10.5 cm)

Unit Weight

0.8 lbs. (0.4 kg)

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Listen Technologies LR-4200-IR

Infrared receiver for the Listentech assistive hearing radiators.

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Listen Technologies LR-5200-IR

Infrared receiver with direct channel select button, for the Listentech assistive hearing radiators.

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Listen Technologies LA-141

Infrared expansion radiator for use with LT-84 transmitter/radiator.

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