Meitner Audio MA3 Network-Attached DAC Translating Transients

Translating Transients

The MA3's response and time domain behaviour is entirely determined by Meitner's proprietary MDAT2 adaptive digital filter algorithm executed on a Xilinx Spartan DSP. Other brands, Denon included, also employ a degree of signal-dependent adaption in their digital filters, but Meitner was the first with its IDAT D/A processor back in 1992/3. Meitner's approach aims to maintain the integrity of transient signals, specifically avoiding the time-domain artefacts that we see with conventional high-order linear phase filters, for example. Specifically, while incoming data is upsampled to a noise-shaped 16xDSD (45.16MHz) bitstream, transient signals are detected using a 'history' of only a few samples and the filter applied that incurs the absolute minimum pre/post-transient 'echoes'.


The most extreme example [see inset Graph] shows the filter applied in response to a momentary transient – note the variable roll-off of –3.9dB/20kHz (44.1kHz data), –3dB/20kHz (48kHz data, black trace), –3dB/40.5kHz (96kHz data, blue trace) but a reduced –3dB/33kHz (192kHz data, red trace). By contrast, the response of Meitner's MDAT2/MDAC2 DSP and 1-bit DAC to signals judged to be more 'steady state' in nature would, by comparison, be ruler-flat. With constantly changing music signals, the digital filter algorithm adapts and segues between filters to maintain the lowest time domain distortion. PM

EMM Labs and Meitner Audio
Calgary, Canada
Supplied by: Audio Visual Technology Solutions, Coventry
07974 735998