QX-280 Series Corporate Power

Quest QX4280 Amplifier

Studio quality sound and plenty of channels - the QX-280 Series is available in a wide range of single and multi-channel configurations. Specifically designed for AV installations and high end commercial sound, where hi-fidelity audio is required.

Powered the latest in quality, energy efficient, Class D amplifiers; the QX-280 Series amplifiers can be integrated into both low impedance, and 70/100V line installations without compromise 

A Closer Look

The QX-280 range consists of three, separate 280 Watt per channel models, available as single, two channel, and four channel variants.

Audio quality is studio class in both high and low impedance operation. High quality class D amplifier technology makes it possible to have a compact single rack format with the right combination of power and channel density.

The transformerless outputs deliver full range audio to all impedance loads from 4Ω to 70/100V systems. Each amplifier channel has a selectable 80 Hz high-pass filter (selectable via a swith located on the rear panel), and a volume control for each channel that can be accessed directly from the front panel. Each amplifier channel is also provided with a thermally controlled cooling fan.


  • High Efficiency Class-D Amplifier(s)
  • 70/100V or Low Impedance Operation
  • Compact 1RU Chassis
  • Auto-Sleep Function
  • Selectable 80Hz High Pass Filter
  • Built-In Limiter Circuit
  • Thermally Controlled Fans
  • AC power range 85-265VAC 50/60Hz.
  • ErP (1275/2008/EC) compliant standby consumption < 0.5W (*per channel)
  • Available in 1, 2 or 4 Channel Models

Energy Conserver

Whether awake or asleep, the QX-280 amplifiers are not hungry for power. The amplifier functions across the power range at an 89.5% efficiency rate.

With a sleep mode mains current draw of less than 0.5 watts per amplifier channel. This is a great benefit for venues with a high amplifier channel count.

The automatic standby functionality mutes an individual amplifier channel after no signal has been detected for 10mins or more; and will put the amplifier into sleep a mode after 30mins. Automatic standby can be turned on and off for individual channels via a switch located on the rear panel.

The operational voltage range of the QX-280 Series is also wide – from 85 to 265VAC, and no manual switching is required for high and low impedance operation. This is a great reliability benefit for installations subject to inconsistent mains supply.

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Made in Australia

Like all Quest products, the QX-280 Series is made to survive in a tough world.

Australian QC and advanced design engineering mean years of trouble free service in professional applications. The QX-280 Series provides a price/performance ratio that is hard to beat.



Peak Output Current 25A
THD+N (1kHz @ 1W / 1kHz ½ Rated Power) 0.022% / 0.015%
Dynamic Range 119dBA
Output Resistance (1kHz) 43.6mΩ
Peak Output Voltage (unloaded) ±140V
Power Output 4Ω 280W
8Ω 245W
70V 250W
100V 240W
DC Offset ±7mV
Frequency Response ±0.1dB 20Hz - 20kHz (1st order 22kHz LPF)
Voltage Gain (@ 1kHz) 32dB


Mechanical Specifications
Net Weight QX1280 - 4.5kg QX2280 - 4.9kg QX4280 - 5.7kg
Gross Weight QX1280 - 7.1kg QX2280 - 7.5kg QX4280 - 8.3kg
Dimensions (H x W x D) 44 x 485 x 304mm
Input Connections 3-Way 5.08mm Captive Screw Connector
Output Connections 2-Way 5.08mm Locking Captive Screw Connector
Mains Power Connection IEC C14
Mains Input Voltage 85 - 265VAC

* All specifications were measured at 240VAC

** Quest Engineering reserves the right to make changes in specifications, or products without prior notice.

*** The figures shown above are ‘real world’, usable specifications and are conservative as a result. Quest Engineering does not believe in portraying misleading or exaggerated specifications.


Contact Quest

Phone: +61 (0) 3 8373 6868

Address: 86 Derby Street, Pascoe Vale VIC 3054 Australia

Postal: P.O. Box 1071 Tullamarine VIC 3044 Australia

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Contact Form

For general enquiries email Quest Directly using the enquiry form below.