ESX QS-FOUR-BT-ISO

The ESX QS-FOUR-BT-ISO is an extremely compact 4-channel Class D amplifier designed to easily boost the power of existing car audio systems. Measuring just 90 x 35 x 80 mm, this power amplifier can be installed even in spaces where there is hardly any room for traditional amplifiers.

The ISO version comes with a 60-cm Plug+Play ISO cable set. This allows the amplifier to be installed directly between the car stereo and the vehicle's wiring harness in compatible vehicles. No major modifications to the existing wiring are necessary.

In addition, the QS-FOUR-BT-ISO features a built-in Bluetooth receiver. This allows music to be streamed directly from a smartphone or tablet to the amplifier. This makes it possible to retrofit modern Bluetooth audio streaming—especially in vehicles with older factory-installed radios or classic and modern classic cars—without having to replace the original radio unit.

Despite its very compact design, the amplifier delivers up to 4 x 60 watts RMS into 2 ohms. At 4 ohms, it delivers 4 x 35 watts RMS. Two channels can each be operated in bridge mode, delivering up to 120 watts RMS into 4 ohms.

The high efficiency of the Class D circuit—up to 90%—ensures low power consumption and minimal heat generation. ESX combines compact electronics with a solid cast heat sink for reliable heat dissipation.

The amplifier can be connected directly to the speaker outputs of a factory-installed radio via the built-in high-level inputs. In many vehicles, the ESX Error Protection System (EPS) prevents error messages from the speaker diagnostic system. Low-level inputs and outputs are also available.

High-pass or low-pass filters with 80 Hz and 12 dB/octave, respectively, can be activated for the front and rear channels. The stereo RCA output can be used, for example, to integrate an active subwoofer or an additional power amplifier into the sound system.

Technical Specifications

• Product Type: 4-Channel Nano Digital Amplifier

• Amplifier Technology: Class D

• Number of channels: 4

• Built-in Bluetooth receiver: Yes

• Bluetooth version: 5.0

• ISO Plug+Play Cable Set: Yes

• Length of ISO cable set: approx. 60 cm
  
  

RMS Output Power at 14.4 Volts

• 4 ohms: 4 x 35 watts RMS

• 3 ohms: 4 x 45 watts RMS

• 2 ohms: 4 x 60 watts RMS

• 4 ohms bridged: 2 x 120 watts RMS

• Speaker impedance: 2 to 8 ohms

• Minimum impedance (bridged): 4 ohms
  
  

Audio and Amplifier Specifications

• Frequency range: 10 Hz – 60 kHz

• Total Harmonic Distortion (THD) at 5 watts: 0.008%

• Signal-to-noise ratio: 101 dB

• Damping factor: 68

• Efficiency: up to 90%
  
  

Input sensitivity

• Low-level input: 200 mV – 5.0 V

• High-level input: 450 mV – 11.0 V
  
  

Filter

• Front high-pass filter: 80 Hz / 12 dB per octave

• Front low-pass filter: 80 Hz / 12 dB per octave

• Rear high-pass filter: 80 Hz / 12 dB per octave

• Rear low-pass filter: 80 Hz / 12 dB per octave

• Filter can be switched on or off as desired

• Full-range operation possible
  
  

Connections and Signal Inputs

• 4-Channel High-Level Input

• High-Level Inputs with ESX EPS Error Protection System

• Low-level inputs for front left/right

• Low-level inputs for rear left/right

• Low-level connections via cable connectors

• Left/Right Stereo RCA Output

• RCA output, for example, for active subwoofers or additional amplifiers
  
  

Power-On Functions

• Automatic Power-On Function

• Signal Detection via VOX

• DC Offset Detection

• Start/Stop Ready
  
  

Bluetooth

• Bluetooth version: 5.0

• Stereo Audio Transmission

• Bluetooth frequency range: 2402–2480 MHz

• Maximum transmitted power: 30.0 dBm

• Direct music playback via compatible smartphones and tablets
  
  

Power Supply

• Operating voltage: 7.3 – 16.4 volts

• External fuse: 25 A

• Suitable for 12-volt vehicles

• According to ESX, average current consumption during normal operation is typically about 5–10 A
  
  

Dimensions

• Width: 90 mm

• Height: 35 mm

• Length: 80 mm

• Dimensions: 90 x 35 x 80 mm
  
  

Additional Features

• Ultra-compact nano design

• Heavy-duty cast aluminum heat sink

• High Efficiency

• Low heat generation

• Built-in Bluetooth receiver

• ISO Plug-and-Play Installation

• No major modifications to the vehicle's existing wiring are required

• Suitable for upgrading many factory-installed speaker systems

• EPS Technology for Preventing Error Messages in Vehicle Diagnostic Systems

• Stereo output for expanding the audio system

• Suitable for front and rear speaker systems

• Bridge mode is possible for compact woofers
  
  

What's Included

• ESX QS-FOUR-BT 4-Channel Nano Digital Amplifier

• ISO Plug+Play Cable Set, approx. 60 cm

• Connection cables for signal inputs and outputs

• User Manual