Ferrum Audio Wandla USB DAC/Preamplifier Lab Report

Lab Report

In almost every respect, the new ES9038PRO DAC-equipped Wandla builds on the performance of the ES9028PRO-equipped ERCO [HFN May '22]. Not only has Ferrum evolved its programme of custom digital filters but the slew-limiting that compromised the high frequency/peak level performance of the ERCO has been solved here with a new I-to-V stage and balanced audio output unveiled in the Wandla. So, distortion not only remains at the fabulously low level of 0.00008%/1kHz at 0dBFs – this being the target specification offered by ESS for its DAC – but this is also maintained at the massive 10V balanced output offered by the Wandla's preamp stage [see Graph 1, below]. Distortion at 20kHz/0dBFs, at this same output, holds to a remarkable 0.00085% over the top 30dB of the Wandla's dynamic range instead of the 0.04% recorded for the ERCO at 20kHz/0dBFs with its lower 2.6V maximum output.

Jitter suppression, meanwhile, remains state-of-the-art thanks both to ESS's patented 'Jitter Elimination' technology and Ferrum's implementation of the DAC with a local clock. Moreover not only is the correlated jitter a mere ~10psec across all sample rates but any clock phase noise is almost wholly banished – visible as the very minimal 'skirt' at the base of the peak [Graph 2]. Back in the analogue domain, Ferrum has retained its low 22ohm source impedance but boosted the achievable A-wtd S/N ratio to an exceptionally wide 120dB. Channel separation is as close to 'dual mono' as you'll see in a single chassis at 140dB/midband while the frequency response(s) are determined both by the incoming sample rate and choice of digital filter. Ferrum's own filters offer an earlier HF roll-off than the ESS defaults. PM


Distortion vs. digital signal level over a 120dB range (1kHz, black; 20kHz, blue). Note extended Y scale


High resolution jitter spectrum via S/PDIF and USB (48kHz/24-bit, with markers)

Max. output level / Impedance (bal XLR) 10.05Vrms / 22ohm
A-wtd S/N ratio 119.8dB
Distortion (1kHz, 0dBFs/–30dBFs) 0.00008% / 0.00065%
Distortion & Noise (20kHz, 0dBFs/–30dBFs) 0.00085% / 0.00085%
Freq. resp. (20Hz-20kHz/45kHz/90kHz) +0.0 to –0.2dB/–0.8dB/–2.0dB
Digital jitter (48kHz/96kHz) 12psec / 8psec
Resolution (re. –100dBFs / –110dBFs) ±0.1dB / ±0.2dB
Power consumption 21W (via Ferrum Hypsos)
Dimensions (WHD) / Weight 217x50x206mm / 1.8kg
Price £2800

Supplied by: Signature Audio Systems
07738 007776