ESX QM-FOUR

The ESX QM-FOUR is an exceptionally compact and powerful 4-channel digital amplifier from the QUANTUM series. Despite its small size, the amplifier delivers a total output of up to 360 watts RMS and is ideal for enhancing the sound quality of existing car audio systems.

Thanks to modern Class D technology, the QM-FOUR achieves an efficiency of up to 86%. The solid cast aluminum heat sink ensures reliable heat dissipation and allows for operation even in tight installation spaces.

For integration into factory-installed sound systems, the amplifier features high-level inputs with the ESX Error Protection System (EPS®) and an automatic power-on function. In addition, individually adjustable high-pass and low-pass filters for both channel pairs allow for flexible adaptation to different speaker configurations.

The built-in clipping LED makes it easy to monitor the signal level. Thanks to its start-stop compatibility, RCA connectors, and compact design, the QM-FOUR offers a wide range of applications.

Technical Specifications

General Characteristics

• Model: ESX QM-FOUR

• Series: QUANTUM QM

• Amplifier Type: 4-Channel Digital Amplifier

• Amplifier Technology: Class D

• Number of channels: 4

• Efficiency: up to 86%

• Speaker impedance: 2–8 ohms

• Bridge operation: possible

• Start-stop capability: Yes

• Cooling: solid cast aluminum heat sink
  
  

RMS Output Power at 14.4 V

• 4 ohms: 4 × 52 watts RMS

• 2 ohms: 4 × 90 watts RMS

• 4 ohms bridged: 2 × 180 watts RMS
  
  

Audio Characteristics

• Frequency response (−3 dB): 10–41,000 Hz

• Signal-to-noise ratio: 101 dB

• Damping factor: over 100

• Total Harmonic Distortion (THD) at 1 watt RMS: less than 0.01%
  
  

Crossover for Channels 1 and 2

• Filter Mode: HPF / OFF / LPF

• High-pass filter (HPF): 40–4,000 Hz

• Low-pass filter (LPF): 40–4,000 Hz

• Bass Boost: 0 / +6 / +12 dB at 45 Hz
  
  

Crossover for Channels 3/4

• Filter Mode: HPF / OFF / LPF

• High-pass filter (HPF): 40–4,000 Hz

• Low-pass filter (LPF): 40–4,000 Hz

• Bass Boost: 0 / +6 / +12 dB at 45 Hz
  
  

Connections and Features

• Low-level RCA inputs: available

• Low-level RCA outputs: available

• Input sensitivity (low level): 0.2–6 V

• Input sensitivity (high level): 0.8–15 V

• High-level inputs with EPS® (Error Protection System)

• Automatic power-on via DC detection at the high-level input

• Input selector switch: 2CH / 4CH

• Clipping LED: present

• High-level connection: via a 20-pin wiring harness

• RCA connectors: via a 14-pin wiring harness
  
  

Power Supply and Dimensions

• Operating voltage for RMS power rating: 14.4 V

• Fuse: 1 × 35 A

• Width: 216 mm

• Height: 39 mm

• Depth: 84 mm