Spectrum™ III Amplified Classroom Audio System

PN: IMA-820
Amplifier | Infrared Microphone Receiver | Audio Mixer







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Spectrum™ III Amplified Classroom Audio System Description

The Spectrum™ III is our most powerful infrared Sound Field System for use in the classroom, larger gathering areas up to 2500 sq ft, 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. One body-worn for hands free presentation and a handheld for individual participation.

When connected to overhead speakers, the Spectrum™ III 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 their 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.

Spectrum™ III Amplified Classroom Audio System Details


  • 2 infrared wireless microphone receivers
  • Power amplifiers: 4 @ 25 W RMS (100 watts total), digital hybrid class D
  • Security Alert contact closure connection
  • Fire Alarm contact closure input
  • Page override (muting) with pass-through to classroom speakers; input level:
  • 100 V, 70 V, 25 V
  • 4 line inputs: DVD, computer, MP3 & aux
  • 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 (MP3) input
  • Rear panel: DVD input, dual RCA
  • Lesson Capture output with level control on rear panel (3.5 mm)
  • ALS output with level control on rear panel (3.5 mm) 5-band equalizer
  • Digital Feedback Guard (DFG) Remote teacher priority over line inputs (enabled by Sapphire microphone)
  • Power sleep mode to conserve energy
  • Drop-in charger connection 5 VDC USB
  • Power up to 8, 8 Ω speakers
  • 2 external microphone sensor inputs, single RCA
  • Rack or shelf/wall mounting kits (optional)
  • WC-400 Wall Mount Cabinet (optional)


Weight 2.375 lbs
Dimensions 7.5 × 8.5 × 1.75 in
Receiver Input

Infrared FM, 2 wireless mic channels


Wide-band FM

Reception Frequencies

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

Infrared Wavelength

850 nm

Tone Signal

Ch. A: 32.768 kHz


50 μs

Frequency Response

40 Hz – 18 kHz, ±3 dB

S/N Ratio

>65 dB

Total Harmonic Distortion

<1% @ 1 kHz

Nominal Deviation

±10 kHz

Maximum Deviation

±25 kHz

External Sensor Input

2, RCA

Connectivity Coverage

1,600 Sq. Ft., 50 ft. line of sight

Aux Inputs

1 dual RCA, 3 x 3.5 mm aux line level (1 anti-hum)

Line Output

Lesson Capture: 3.5 mm with gain control – front panel
ALS: 3.5 mm with gain control – rear panel

Page Input

2-pin Phoenix; 3 settings: 100 V, 70 V, 25 V


Level control

Security Alert

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

Fire Alarm

Contact closure (mutes audio)


5-band, ±12 dB

Output Power

4 amplifiers @ 25 W (RMS), 100 W total

Output Impedance

4 Ω

Speaker Connection

4-pin Phoenix connectors

Charger Output


Power Supply

19 VDC / 6.3 A; CE, CSA and UL listed


Front of IMA-820 receiver/amplifier
  1. Power on/off
  2. CH A Microphone Volume Control
  3. CH B Microphone Volume Control
  4. DVD Volume Control
  5. Computer Volume Control
  1. Aux Volume Control
  2. MP3 Volume Control
  3. MP3 Input (3.5 mm)
  4. Lesson Capture Volume Control
  5. Lesson Capture Output (3.5 mm)
Spectrum III Front Panel


Maxim III IMA 520 Rear Panel Details
Back of IMA-820 receiver/amplifier
  1. Speaker Output - Four Channel Four pin Phoenix connector
  2. Fire Alarm Input- contact closure
  3. Page Mute Input - 2 pin Phoenix
  4. Page Sensitivity control
  5. Page impedance selector
  6. ALS gain control
  7. ALS Output (3.5 mm)
  8. Five band digital equalizer ±12 dB
  1. RS-232 (Tx, Gnd, Rx) 3-pin
  2. Security Alert - contact closure
  3. Aux-Mic Input Selector
  4. Aux-Mic Input (3.5 mm)
  5. Computer Input (3.5 mm)
  6. Computer Anti-hum ON/OFF
  7. DVD dual Mono Inputs (RCA)
  8. Two IR Mic Sensor Inputs (RCA)
  9. 5 Volt USB output for BRC-60
  10. Power Input: 19 VDC 3.4 A

Spectrum™ III Amplified Classroom Audio System 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™ III Sound Field 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™ III Amplified Classroom Audio System Downloads

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