Redback Phase5 Boost Public Address (PA) 2x125W Amplifier (4372)


A 4372

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Manufactured in Australia to stringent engineering standards, the Phase 5 amplifier series boasts remarkable performance and outstanding reliability. With over two years of design and development, the evolution of Phase 5 involved extensive consultation with professional sound contractors and installers nationwide. The numerous features make this amplifier series ideal for the most demanding pro sound and industrial PA system applications. Redback Phase 5 amplifiers incorporate on-demand multi-staged thermally cued fan-forced cooling.

The output power stage is thermally monitored, allowing a long-life computer-style cooling fan to automatically switch "off" or "on" as needed, directing airflow through a specially designed tunnel heatsink. In quiescent or regular cycle paging mode, the fan remains inactive. An over-temperature sensor shuts down the amplifier in extreme overheating conditions, such as severe overload or misuse, with automatic restart once normal temperatures are restored.

The output voltage is limited to a maximum of 105V RMS, regardless of load impedance, to prevent damage to speaker loads. Standard 100V line PA amplifiers can deliver up to 180 volts or more under high drive and very light loading conditions, which can quickly destroy connected loudspeakers.



  • Robust design incorporating latest Mosfet technology
  • Very Low noise and distortion
  • 100V outputs
  • 240V AC or 24V DC operation
  • Multi stage thermally cued fan cooling
  • Output Peak Limited
  • Thermal Overload protected
  • Signal Presence Indicators
  • Fault Indicators
  • Power Status Indicators
  • Rack Mountable (suits 19 inch racks)


Power Output: 2 x 125 Watts RMS

Distortion: < 0.5%, @ 1kHz

Output Line: 100V


Frequency Response

Mic Inputs: 50Hz - 12kHz, -3db

Mic Sensitivity (3 pin XLR): 500mV


Signal to noise ratio

Mic Inputs: > 75db below rated output

Line Output: 600Ω balanced, 0dB , 3 Pin XLR


Output Connectors

Speakers: Screw terminals


Input Connectors

Inputs: 3 pin XLR balanced

24V DC power: Screw terminals

240V AC power: IEC power connector



Mic inputs: Volume

Power: On/off switch

Indicators: Power, signal present, output peak limiting, overtemp ,current limit, Protect, Half Power, 24V DC, Mains

Power Supply: 240V AC or 24V DC

Fuse Protection: 7.5A AC , 2x 10A DC

Dimensions: ≈483W x 410D x 88H


*Specifications are subject to change without notice.

Redback Phase5 Boost Public Address (PA) 2x125W Amplifier (4372)

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Australian owned since 1980


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