Spectrum™ Receiver Amplifier

PN: IMA-840

Amplifier | Infrared Microphone Receiver | Audio Mixer







Spectrum™ Receiver Amplifier 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 2.4 lbs
Dimensions 7.5 × 8.5 × 1.75 in
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


Front of IMA-840 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. Conference Input Volume Control
  3. Conference Input (3.5 mm)
  4. Conference Output Volume Control
  5. Conference 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 ±10 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 6.3 A

Spectrum™ 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™ 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™ Receiver Amplifier Downloads