Auto Sound Special Award for BRAX DSP & MX4 PRO

Japan’s leading in-car electronics magazine Auto Sound honored the combination of the BRAX DSP and MX4 PRO amplifier with their highest award.

The special feature of this combination is, in particular, our proprietary DiSAC (Digital Signal Analog Controlled) volume control.
As a novelty in the car audio segment the volume adjustment takes place just before the output stages of the MX4 PRO amplifier that drive the speakers ­ therefore the volume control happens in the analog domain without sacrificing any signal resolution. The BRAX DSP embeds the volume information in the digital SPDIF data stream which is then decoded inside the MX4 PRO.

"We are very happy that Japanese audiophiles appreciate our high-end products. It makes us  proud and pleased whenever this affinity is reflected in prizes such as the Auto Sound Award. We thank the editors of Auto Sound Magazine and our Japanese distributor M'S Line Co., Ltd.", says company founder and CEO Heinz Fischer.


DiSAC (Digital Signal Analog Controlled) volume control


In a car audio system there are typically two possibilities to control the playback volume.
a) The volume will be adjusted in the signal source (e.g. the car radio / head unit):
This is the predominant method, but it has a disadvantage as soon as there is an additional digital signal processor in the audio path. The full resolution of the DSP can only be exploited when the volume of the source is set to full-scale output. Otherwise audio bits get “lost” so that at very low volume levels the sound lacks of precision. But this loss can also happen if no DSP is in the signal path between head unit and amplifier as most of the radios today incorporate a digital volume control which also has a negative effect on the signal resolution at low volume levels.

b) The volume will be adjusted in the digital signal processor (DSP):
In this case the signal source delivers a full-scale signal so that a DSP in the signal path can operate under best possible conditions without truncating any bits, e.g. during AD conversion process. A remote control connected to the DSP will then be responsible for adjusting the volume inside the signal processor in the digital domain, but this also has a slight impact on sound quality.

The perfect solution:
The BRAX DSP in combination with the MX4 PRO follows a different, yet the most consequent and extensive approach in order to avoid any degradation of sound quality. Audiotec Fischers exclusive and proprietary “DiSAC” technology operates perfectly if either the audio source does not incorporate any volume adjustment or the source always delivers a high signal level. In that case the audio processing inside the BRAX DSP is done without reducing the audio resolution at any time. For adjusting the playback volume either the cable remote URC.3 or the display remote DIRECTOR can be chosen.

The speciality lies in the fact that the volume information from the remote will be encoded inside the BRAX DSP and embedded into the digital audio data stream of the SPDIF outputs and thus transferred to the MX4 PRO.
The MX4 PRO itself is able to extract and decode the volume information from the digital data stream, using this to adjust the lossless analog volume controllers (PGA’s) after the DA converters. This simply means that the volume control takes place in the signal path where it does not have any negative impact on sound quality, actually just before the output stages that drive the loudspeakers. This type of volume control is truly an uniqueness in the car audio segment and proofs once again that Audiotec Fischer didn’t spare any effort to redefine the pinnacle of sound quality once again.


Key features BRAX DSP:

  • Three extraordinary powerful “fixed point” Sigma350 audio DSP's with 64 Bit resolution and a total of 3.6 billion MAC operations per second calculating power
  • State-of-the-art Asahi Kasei "Velvet Sound" A/D and D/A converters with a native resolution of 32 Bit
  • 192 kHz sample rate for ultra High-Res audio bandwidth up to 80 kHz
  • Benchmark specifications for e.g. signal-to-noise ratio and total harmonic distortion, close to measuring limits
  • Modular 8-channel in / 12-channel out concept with exchangeable stereo analog or digital input / output modules for covering all possible system configurations
  • 4 stereo input modules with either analog RCA / Cinch and Highlevel or digital optical / coaxial SPDIF input
  • 6 stereo output modules with either analog RCA / Cinch or digital optical / coaxial SPDIF outputs
  • Output modules with switchable sampling rate of 48, 96 or 192 kHz
  • Analog output modules with variable filter characteristics and switchable output voltage of 2, 4 or 8 Volts
  • Muting of the analog output stages via relays with gold-plated contacts
  • Additional stereo SPDIF input (optical / coaxial) as well as a Link module for system extensions
  • Double BRAX Extension Card slot (BEC) for optional input / output modules like Bluetooth® Audio Streaming, High Resolution Audio Streaming via USB etc.
  • Unique DSP Sound Effects such as the “Augmented Bass Processing” which dynamically optimizes the bass response of the subwoofer, the “StageXpander” that significantly widens the stereo perspective, the “RealCenter” function, which allows a perfectly focussed sound staging for both driver and co-driver and much more
  • Incomparably complex power supply concept with a total of 55 voltage regulators and start-stop capability
  • DiSAC (Digital Signal Analog Controlled) volume control in combination with BRAX MX4 PRO
  • ACO – Advanced 32 Bit CoProcessor for all control and communication tasks
    • 10 internal memory locations for sound setups
    • Setup switching within milliseconds
    • High-speed data transfer and improved usability
  • Solely made from the very best components with lowest tolerances, fitted in a rock-solid aluminum housing
  • Eight-fold layer main PC board for ultra-low impedance signal and power supply transmission
  • Analog audio signal transmission solely on the in- and output modules


Key features BRAX MATRIX MX4 PRO:

  • Two digital stereo digital inputs in SPDIF format (optical and electrical) with a sampling rate up to 192 kHz
  • DiSAC (Digital Signal Analog Controlled) volume control for the digital signal inputs, controllable via BRAX DSP
  • Optimized quad-layer PCB design for maximized power and signal flow and increased output power
  • Lossless switching of the input signals via relays with gold-plated contacts
  • Best possible impulse response due to abstinence of coupling capacitors in the signal path
  • Incredible damping factor of more than 1,400 @ 4 Ohms for perfect speaker control
  • Maximized signal-to-noise ratio due to power supply synchronization
  • Extremely complex and regulated switch-mode power supply
  • Eightfold-contacted capacitors with a total capacitance of 40,000 μF and lowest possible ESR as well as a 300 A suppressor choke coil to smooth power supply peak currents
  • Separate connector for BRAX power stabilizer
  • Loudspeaker protection circuit via sophisticated high current power relays
  • Specially designed toroidal transformers made of high permeability core materials for highest possible saturation currents
  • 32 hand-selected high-end MOSFET transistors for lowest tolerances and outstanding measurement data
  • Engraved serial number on a stainless steel plate
  • Impedance independent output power of  300 Watts RMS per channel
  • 4, 2 and 1 Ohms stable
  • Processor and temperature controlled fan in bottom plate
  • Massive heat sink made of a special aluminum alloy for optimum cooling of all power transistors