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We set out to make what we believe you, as a customer, will value. High audio quality, low losses, small size, robustness, flexibility and long life. With our Sierra loop-design we manage to keep the distortion at a very low level throughout the audio band, and at the same time maintaining a first-order characteristic with -3 dB at 100 kHz giving very low phase shift at 20 kHz. The output impedance of Engine-400 has been verified to just a few milliohms in the audio band, and the noise is less than 30 uVrms giving a dynamic range of 1.3 million times or 122 dB. Engine-400 uses the high-density multilayer PCB as heat sink thereby keeping the building height down. Low impedance connections to your PCB is provided through massive, gold plated, copper tellurium pins. As a customer, you select which electrolytics, filter capacitors, VA+/- and VDR regulators you prefer to use. You are also free to handle the alarms that is sent out from Engine-400 in the way you wish. This provides you with the maximum design freedom without having to deal with complex switch mode electronics design.


  • 0,003 % THD+N @ 1Wrms
  • <2 mΩ output impedance in the audio band
  • <17 degrees phase shift in the audio band
  • <2.5 W idle losses (1.8 W in output stage)
  • Convection cooling, no heat sink is needed
  • Clip detect output signals high distortion
  • Over-temp. warning flag
  • Click-free disable input

Key Performance Parameters

Output Power 1 % THD+N, 20 Hz – 20 kHz 400 W (4 Ω)300 W (2 Ω)
Minimum load impedance 2 Ω
Maximum amplifier efficiency
Maximum total amp+psu efficiency
Supply voltage input +/- 60 VDC+/- 32 VDC
Peak output current 22 A
Dynamic range 124 dB
Amplifier maximum output voltage per channel 56.57 V
Output referenced idle noise (A-weighted) 25 µV
THD+N 1W/1kHz 0.002 %