LT-84 ListenIR Infrared Transmitter

  • An affordable, effective, and expandable IR transmitter ideal for use in small to mid-size spaces such as classrooms, courtrooms, boardrooms, and more
  • Multiple frequency options offer additional flexibility and simplify installation and setup
  • Offers gapless line of sight coverage of up to 2,787m2 (dependent on the number of LA-141 expansion radiators used).
  • One-cable design utilizes a single CAT-5e cable to carry both power and signal to LA-141 expansion radiators
  • Max four LA-141 expansion radiators per LT-84


Frequency Response
20 Hz - 20 kHz (+/- 1 dB) Line Input63 Hz - 15 kHz (+/- 3 dB) 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, two (2) Red LEDs, Green LED indicates Audio presence and Red LED indicates peaks in the audio
RJ-45 Amber LED
Solid Amber indicates carrier is present and IR is being transmitted
RJ-45 Green LED
Solid Green indicates power is applied to unit, flashing indicates 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 Line Cord
IEC line cord, North America Type B (LT-84-01), Asia and UK Type G (LT-84-02), Euro Type C (LT-84-03), Australia Type I (LT-84-04)


Black with White Silk Screening
Unit Weight with Power Supply
1.8 lbs. (0.8 kg)
Shipping Weight
3.4 lbs. (1.54 kg)
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.
(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)


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


FCC part 15, ICS-03, CE, UL, CUL, C-Tick, CCC, PSE, KC, GS, RoHS, WEEE
Power Supply Compliance Marks

Specific References