Integrated Amplifiers

In practice, the Artera Solus has the same four digital filters we saw in Quad's earlier Artera Play model – Narrow, Smooth, Wide and Fast. 'Narrow' is a traditional linear phase filter offering an excellent 120dB stopband rejection and very flat response (–0.15dB/20kHz), albeit with significant ringing [see black traces, inset Graph]. The 'Smooth' filter is also a linear phase type but with a very abrupt cut-off just prior to the Nyquist frequency (–0.15dB/19kHz to –3.5dB/20kHz with CD and –1dB/42kHz to –13.2dB/45kHz with 96kHz media). The 'Wide' filter is a slow roll-off type, not dissimilar to Pioneer's interpolative Legato Link filter of the 1980s with its minimal ringing (much reduced time domain distortion) but curtailed treble (–3.1dB/20kHz) with CD/48kHz sources [red traces, inset Graph]. The 'Fast' filter takes this a stage further, incurring almost no ringing but offering almost no stopband/alias rejection by way of compromise. This filter is best suited to higher sample rate inputs where the treble loss is inaudible and alias images are pushed out well beyond the audioband. PM