PN: IMA-840
Amplifier | Infrared Microphone Receiver | Audio Mixer








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Spectrum™ Description

New & Improved for 2021! The Spectrum™ is our most powerful infrared classroom audio system for use in larger gathering areas up, or a room where you need more than four speakers.

It is the ultimate audio system for group presentation; whether in a classroom, boardroom, or conference area. Its two channel receiver allows the simultaneous use of two wireless infrared microphones. Our Sapphire pendant  is ideal for hands free presentation while our IRH-35 handheld can be passed around the room for individual participation.

When connected to overhead speakers, the Spectrum™ ensures that crystal clear sound is delivered to every seat in the room.

Four auxiliary line inputs to integrate various media devices to supplement your presentation material for added engagement, plus connections for intercom, fire alarm, and security alert.

An ultrasensitive dome sensor mounted to the ceiling renders 100% reliable signal connectivity of the microphone throughout the room.

With our advanced infrared (IR) engineering, TeachLogic systems are less susceptible to outside interference and all transmission will be contained in the room. IR will not pass through a solid surface, thus eliminating transmission into an adjacent room and providing absolute security. What is said in the room stays in the room.

Why IR?

Spectrum™ Details


  • Amplifier: digital hybrid class D
  • Powers up to eight (8 Ω) classroom speakers
  • Video Conference Sync w/ EchoGuard™
    • Front panel “Conference” input & output: connects to host computer to synchronize classroom audio w/ video conference application
    • EchoGuard™ prevents remote audio from being looped back into conference audio
  • 4 line inputs:
    • Rear panel: 3.5 mm auxiliary input (mic or line level switch) Rear panel: 3.5 mm computer input w/ anti-hum (On/Off switch) | Front panel: 3.5 mm auxiliary (Conference) input | Rear panel: DVD input, dual RCA
  • Assistive Listening System (ALS) output with level control on rear panel (3.5mm)
  • Connection to building paging system
    • Mutes all audio inputs to allow page to be heard (Page Muting)
    • Passes page signal to classroom speakers (Page Pass Through)
    • Feature can be turned off w/ a selector switch. Note: not intended as a life-safety audio transmission feature
    • Pages pass through to Assistive Listening System and Conferencing outputs
  • Supports teacher security alerting function from wireless microphone (IRT-60)
  • Fire Alarm connection: mutes all audio sources when fire alarm sounds
  • May be controlled by third-party RS-232 devices for all input levels (volume up, down, and mute)
  • Digital Feedback Guard (DFG): reduces chances for audio feedback
  • Remote teacher control over line inputs (enabled by Sapphire microphone)
  • Low-power standby mode (both automatic and manual activation)
  • Drop-in microphone charger connection 5 VDC USB


Weight 1.95 lbs
Dimensions 7.5 × 8.5 × 1.75 in
Amplifier Output Power

100 W RMS, 4 x 25 W channels

Receiver Input

Infrared FM, 2 wireless mic channels


Wide-band FM

Reception Frequencies

Ch. A: 2.08 MHz, Ch. B: 2.54 MHz


10 kHz Nominal, 25 kHz Maximum


50 μs

Tone Key

Ch. A: 32.768 kHz

Infrared Wavelength

850 nm

External Sensor Input

2, RCA, powered ports

Connectivity Coverage

1,600 Sq Ft per sensor, up to 2 sensors supported

Total Harmonic Distortion

<1% @ 1 kHz

Frequency Response

20 Hz – 20 kHz, ±3 dB

Line Level Inputs

4: 1x dual RCA, 3x 3.5 mm

Anti-Hum Balun

Present on 1 Aux input for computer

Wired Mic Input

1 aux input switchable to mic input

Line Outputs

Conferencing: 3.5 mm with gain control – front panel
Assistive Listening System: 3.5 mm with gain control – rear pane

Page Input

2-pin Phoenix; 4 V, 25 V or 70 V normal

Page Input Sensitivity

51 mV min

Security Alert

Contact closure (COM, N/O, N/C)

Fire Alarm

Contact Closure by fi re panel mutes audio

Output Impedance

Rated Load: 4 Ω minimum impedance


5-band, ±10 dB

S/N Ratio

65 dB

Speaker Connection

4-pin Phoenix connectors

Charger Output


Power Supply

19 VDC / 6.3 A CE, CSA and UL listed

Spectrum™ Components

Classroom Component Layout

  • Sapphire (IRT-60) wireless pendant transmitter, a high-quality cardiod microphone with lanyard.
  • ICS-55 Ceiling Sensor gives 360-degree infrared coverage for optimal audio performance.
  • Spectrum™ amplifier/receiver to support classroom audio sources.
  • SP-628 Ceiling Speakers (four shown) provide excellent quality voice reproduction.
  • SP-2000 Wall Mount Speakers (optional), allow for installation when ceiling is not accessible.

Spectrum™ Downloads

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