Slogan: sound technology

DSP-Plate Amplifiers with Pascal Amp Modules and Dante Support

Please, note that we can only deal with commercial customers

PPA midres

You can download a high resolution image and a leaflet.
More Downloads on our download-page

The PPA series provides a high-quality DSP-powered amplifier solution for active loudspeakers.

It features Pascal high-power modules, analog, digital and Dante inputs and is available in different configurations for various kinds of speakers.
Signal processing is done in 32 bit floating point on an Analog Devices Sharc DSP and uses dual range ADC for high dynamic input range.
Besides usual IIR X-Overs and EQs, also FIR filters are available for linear phase system response.
An advanced limiter concept protects speakers and prevents amp and PSU overheating.
Programming can be done via USB and the included touch display (see bottom of this page).
A sophisticated user interface for programming and easy-to-use FIR filter creation is provided.


  • 32-bit floating-point signal processing using a Sharc-DSP
  • linear phase FIR and IIR-Crossovers, EQs
  • Advanced Limiter concept with
    • dual band look ahead Peak-Limiter in each output
    • dual band RMS limiter in each output
    • Overall power supply limiter
  • USB connection for programming via remote software
  • Touchscreen for controlling the unit
  • High dynamic range (128 dB(A) dual range converter input, 112 dB(A) output)
  • Analog, AES/EBU and Dante input
  • Pascal high-power amplifier modules and PSU
  • 11 models with active cooling
  • 7 models with passive cooling

System Design and User Operation

The units can be programmed with several system presets by the system developer.
End users are allowed to adjust room EQs, gains and delays in a user mode and store user presets without touching the system presets.
OEM customers can provide keyfiles to enable GUI features for end users.
The touch panel shows level meters, limiter operation and allows switching presets and inputs.

OEM Solutions and Customization

For high volume customers, Four Audio supplies custom designs with
reduced features tailored to the needs of the customer.
E.g., standalone operation of DSP and amplifier without using the touch
display is possible.

Contact Four Audio for more information.

Signal Processing

Limiters     Look-ahead peak limiter, RMS limiter, both dual band
      overall power supply limiter
EQs     Bell / notch filter, allpass, shelving filter 6dB / 12 dB
X Overs     Bessel, Butterworth, Linkwitz-Riley, Critical
FIR     linear phase X-over and linear phase loudspeaker equalization
Others     input delay, output delay, phase inversion, gain


GUI Software with Developer and User modes to create developer and user presets.
Interactive operation on channel parameters and EQing.
Advanced easy-to-use FIR generation from speaker measurements with defined latency.

Common Technical Data

Max input voltage     23 dBu
Analog input SNR     128 dB(A)
Output SNR     112 dB(A)
Mains input voltage     85 – 265 VAC


All models provide over current, DC, temperature and high frequency protection.
The 1600/2200 models additionally feature over-/undervoltage protection.

PPA model overview

PPA Display with Touch Panel Introduction