Loudspeaker Management System

(end of life)

Crystal clear sound.

For crystal clear audio from your loudspeaker system, Four Audio provides a loudspeaker management system with yet unheard audio performance, freely combinable IIR and FIR equalization and separate precision peak and RMS limiters in each output.

Download our Flyer for an overview.
More downloads on our downloads page.

Variants of the HD2

The HD2 is available with and without Dante support. Additionally, blackbox devices are available with and without Dante support. For installations where a direct interface at the device is not necessary or unwanted, blackbox devices reduce costs significantly.

Modules For Customized Solutions

The HD2 is also available as a module to be mounted inside speaker cabinets or self-designed housings. Just provide voltage supply and in- and output jacks. As well as the HD2 devices, the modules are remote controllable by Ethernet. PCB sizes are 11 × 13 cm (4 outputs) or 20 × 13 cm (8 outputs).


  • 96 kHz / 48 bit processing
  • ADC inputs configurable to provide 4 normal or 2 dual range inputs with extended dynamic range
  • AES / EBU digital IO
  • Dante audio network support
  • Wordclock In/Out (Dante)
  • sample rate converter
  • 8 analog outputs
  • operation via ethernet
  • operating software (Win/Linux/Mac) provided
  • mainboard available for customized solutions
  • front panel or blackbox version available
  • also available with 4 outputsh

Signal Processing

  • IIR filters: up to 96 fully parametric high precision filters freely configurable
  • IIR crossover filters with 6-60 dB/octave
  • FIR filters: 1 provided for each output channel
  • Mixed linear and minimum phase equalization possible
  • Max. frequency resolution: 3 Hz
  • Separate limiter thresholds for amps (peak and RMS) and loudspeakers (peak and temp.)
  • Interface to Monkey Forest for FIR filter and limiter calculation
Audio Performance
Max. input level +28, +21, oder +15 dBu (selectable)
Max. output level +18 dBu
Frequency Response (-0.5 dB) 4 up to 45 kHz
Dynamic Ranges
ADC > 130 dB (dual range mode)
118 dB (single range mode)
DAC 121 dB
Overall 121 dB (dual range mode)
THD (1 kHz)
ADC -113 dB (+4 dBu)
-105 dB (0 dBFS)
DAC -110 dB (+4 dBu)
-102 dB (+18 dBu)

All values ref. 20 Hz – 20 kHz, linear weighting


The following plots are taken from a PDF containing audio perfomance measurements executed with a UPD (Rohde + Schwarz). Click on the images to enlarge them.