Outboard DACs

I discuss Meitner's innovative MDAT2 upsampling and 16xDSD MDAC2 DAC technology in our boxout but while the former determines the frequency response, stopband rejection (106dB at 48kHz) and time domain behaviour, it's the '16xDSD' DAC that has greatest influence over noise, low-level resolution, high frequency distortion and jitter. Here there's a maximum (balanced) 4.21V output offered from a 145ohm source impedance where distortion is lowest at –10dBFs (1.35V) through the bass/mid at a fabulous ~0.00005%, lifting to 0.0006% at 20kHz. At lower digital levels the ultrasonic requantisation noise from the 16xDSD DAC architecture becomes more significant but, at –30dBFs/20kHz, noise at 100kHz is still a full 90dB lower in level. This is consistent with a DAC processing what might otherwise be described as 'raw DSD128' data [as seen in our HD Music section] but it is sufficient to explain the ~25dB 'step' in THD+N between 1kHz and 20kHz [black vs blue infills, Graph 1. Note shifted 0dB to –140dB Y axis].

The S/N is a wide 113dB (A-wtd, re. 0dBV) and resolution good to ±0.05dB over a 100dB dynamic range and ±0.2dB over a full 110dB dynamic range, suggesting an effective and very fine resolution of some 19-20 bits for the MA3. Both digital and analogue engineering are at play here, the latter also assisting in the super-wide 135dB midrange channel separation, falling to a still-impressive 110dB at 20kHz. The channel balance is good to ±0.01dB, as expected with Meitner's precision digital volume control. Digital jitter is low but not vanishingly so, with a correlated figure of ~110psec at most sample rates joined by an uncorrelated, noise-like jitter seen as a broadening of the J-Test signal [see Graph 2, below]. PM