Network Audio Players/Servers

In common with the earlier Altair G1, this G1.1 variant offers some user-selectable 'sound tuning' in the form of four alternative digital filters – Precise, Dynamic, Balance and Smooth. The response is flattest with all sample rates via the Precise filter, a fast roll-off linear phase type [red trace, Graph 2] offering a respectable 83dB stopband rejection (but with extended pre/post ringing) reaching out to –0.1dB/20kHz, –0.7dB/45kHz and –2.2dB/90kHz with 48kHz, 96kHz and 192kHz data respectively. The Dynamic filter is an apodising type [black traces, Graph 2] that shows ±0.15dB ripples just prior to its –1dB limits of 20kHz, 44kHz and 73kHz with 48kHz, 96kHz and 192kHz media, but offers a full 92dB stopband attenuation and less group delay than 'Precise'. The Balance filter is a slow roll-off linear phase type [blue trace, Graph 2] with reduced pre/post ringing but a poor 14dB stopband rejection and earlier treble roll-off. 'Smooth' [green traces] is a minimum phase version of Balance, these latter two filters showing off their best at higher sample rates.

With the Precise filter as default, the Altair G1.1 delivers a useful 4.2V output from a low 5ohm source impedance. The ESS9038Q2M DACs maintain a low 0.0003-0.0005% distortion (20Hz-20kHz), falling to 0.00005-0.0002% over the top 15dB of its dynamic range [see Graph 1], and while Auralic specifies its own '72 Femto Master Clock' the jitter rejection of these ESS DACs is already well proven, this falling to <10psec across all sample rates and inputs. The A-wtd S/N is a wide 114dB and resolution is good to ±0.1dB over a 100dB dynamic range and ±0.3dB over a full 110dB, suggesting a 19-bit resolution for the Altair G1.1. Finally, midrange channel separation is a very wide 130dB, falling to a still-impressive 105dB at 20kHz. PM