dCS Vivaldi APEX Outboard DAC Lab Report

Lab Report

Comparisons with the full Vivaldi 'stack' [HFN Feb '13] and Vivaldi One [HFN Feb '18] show small, steady improvements in the evolution of dCS's Ring DAC and analogue technology. The analogue output buffer still has a fabulously low, cable-agnostic 480mohm source impedance and offers a maximum variable output up to 5.88V – ideal for driving power amplifiers directly. The A-wtd S/N ratio is now fractionally higher at 117.1dB and low-level resolution good to ±0.3dB at –120dB. Distortion remains as low as ever through bass/midrange at <0.00009% over the top 20dB of its dynamic range and is even fractionally lower in the APEX at 20kHz where THD falls between 0.0001-0.0003% over the top 30dB [see Graph 1, below, and note the expanded 0-140dB Y scale]. Correlated jitter looks to have increased to 120psec (48kHz/24-bit data) but that is only because the ±5Hz, ±7Hz, ±9Hz, etc, sidebands are now exposed by the elimination of random jitter/phase noise.

Channel separation is >120dB (20Hz-20kHz) while the frequency response(s) depend on your choice of filter, all six delivering a ruler-flat ±0.05dB (20Hz-20kHz) with CD media albeit with variable stopband attenuation (108dB, 57dB, 17dB and 7.3dB, Filters 1-4, respectively). Filter 5 is a minimum phase type with significant post-ringing and Filter 6 a linear phase type with lower amplitude, but more extended, pre/post ringing [orange/purple traces, Graph 2]. Filters 1-4 are linear phase for all sample rates and offer responses of –22dB/45kHz, –0.7dB/45kHz, –29dB/39kHz and –10.6dB/ 45kHz, respectively, with 96kHz media and –13dB/90kHz, –7.3dB/90kHz, –23dB/77kHz and –17.9dB/90kHz [black, red, cyan and green traces, Graph 2], respectively, with 192kHz files. PM


Dist. vs. 48kHz/24-bit digital signal level over a 120dB dynamic range (1kHz, black; 20kHz, blue)


Frequency/impulse Filter responses [Filter 1, black; 2, red; 3, cyan; 4, green; 5, orange; 6, purple]

Maximum output level / Impedance 5.885Vrms / 480mohm (XLR)
A-wtd S/N ratio (LPCM / DSD) 117.1dB / 116.8dB
Distortion (1kHz, 0dBFs/–30dBFs) 0.00004% / 0.00009%
Distortion & Noise (20kHz, 0dBFs/–30dBFs) 0.00025% / 0.00025%
Freq. resp. (20Hz-20kHz/45kHz/90kHz) +0.0 to –0.04dB/–0.dB/–13dB
Digital jitter (48kHz/96kHz) 120psec / 10psec
Resolution @ –100dB/–120dB ±0.1dB / ±0.3dB
Power consumption 21W (1W standby)
Dimensions (WHD) / Weight 444x151x435mm / 16.2kg
Price £33,000

Data Conversion Systems Ltd
Supplied by: dCS Ltd
01954 233950