Spectrum™ III Receiver Amplifier

PN: IMA-820

Amplifier | Infrared Microphone Receiver | Audio Mixer

The Spectrum™ III is our most powerful Sound Field System for use in the classroom. It supports not only the features that every classroom needs to control multimedia audio, but also the integrations to ensure that all school communications are heard: pages, fire alarm, and security alert. When paired with wireless microphones, the Spectrum™ III ensures that crystal clear sound is delivered to every seat in the room.







Spectrum™ III Receiver Amplifier 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)


Receiver Input

Infrared FM


FM wide-band

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

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 panelALS: 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 V DC / 6.3 A; CE, CSA and UL listed

Dimensions 7.5 × 8.5 × 1.75 in
Weight 2 lbs 6.4 oz


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 Pass Through 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 Receiver Amplifier 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 Receiver Amplifier Downloads

Spectrum™ III Receiver Amplifier Frequently Asked Questions

  • add_circleremove_circle_outlineMy receiver won’t turn on – the power light is off. What should I do?

    • Verify that the power supply is plugged into both the receiver and a working wall outlet.
    • Test with another power supply.