Network Audio Players/Servers

In the nine years since we tested the original Bricasti M1 [HFN Jun '11] and then the 'Gold Edition' [HFN Oct '16] the design has evidently been 'finessed' to the point where this more affordable M3 version could be derived, complete with custom DSD DAC and headphone amplifier. For LPCM inputs the same Analog Devices AD1955A DACs still define the very low 0.00016% distortion through the midrange at its (fixed) 4.0V peak output, falling to 0.00007% at –10dBFs and 0.00025% at –30dBFs [see Graph 1, below]. As before, there's a slight increase in 3rd harmonic distortion to 0.0017% at 20kHz falling to 0.00035% between –10dBFs and –30dBFs (a function of the analogue stage) while the A-wtd S/N ratio is boosted by a few dB to 114.5dB and low-level resolution also improved to ±0.1dB over a full 100dB dynamic range.

Bricasti's DDS (Direct Digital synthesis) clocking is retained for the M3 but jitter is not as vanishingly low as it was in the M1. Numerically high at 1915psec, the specific jitter sidebands are nevertheless very low rate at ±15Hz, ±25Hz, ±35Hz and ±45Hz, so the subjective impact will be reduced. Bricasti has elected to offer both linear and minimum phase digital filters as part of its integral 8x upsampling regime [Graph 2, below]. It specifically recommends not upsampling data in an upstream media player/server but to deliver the files in native form to the M3. Both filters offer the same 105dB stopband (image) rejection and very similar response curves that reach –0.15dB/20kHz with 48kHz media and rolls steeply away beyond –3dB/36kHz (96kHz files) and –3dB/60kHz (192kHz files). These engineered roll-offs are earlier than typical but are not inherently 'wrong'. PM