Outboard DACs

In the ten years since we tested the original M1 [HFN Jun '11], the 'Gold Edition' [HFN Oct '16] and the more affordable M3 version [HFN Jun '20], Bricasti has refined both its hardware and firmware. For LPCM inputs there's a new bespoke ladder converter and also the same Analog Devices AD1955A DACs that define the very low 0.0004% distortion through the midrange at its (fixed) 4V peak output, falling to 0.0001% at –10dBFs and 0.00018% at –30dBFs [see Graph 1, below]. As before, there's a slight increase in 3rd harmonic distortion to 0.0027% at 20kHz falling to 0.0003% between –10dBFs and –30dBFs (a function of the balanced analogue filter circuit) while the A-wtd S/N ratio is broadly unchanged at 113.9dB.

Bricasti has retained both linear and minimum phase digital filters but, as part of the latest update, has introduced additional versions of each. The new 'Linear 1' [black impulse, Graph 2] and 'Minimum 1' have slightly reduced coefficients over the original 'Linear 0' [red impulse] and 'Minimum 0' versions. The fractionally reduced ringing seen in the '1' filters is traded for an equally small decrease in stopband rejection (92dB vs. 105dB) and a very slightly earlier cut-off (–0.3dB/19.6kHz to –1.4dB/20kHz vs. –0.18dB/19.6kHz to –0.19dB/20kHz). These latter comparisons are for filters '1' versus filters '0'. At higher sample rates Bricasti's native file processing delivers a slightly earlier roll-off than we see with off-the-shelf implementations. Featuring –3dB points at 35kHz and 60kHz with 96kHz and 192kHz inputs, respectively, the cut-off is steep at –15dB/40kHz and –25dB/80kHz [red and green traces, Graph 2]. PM