Integrated Amplifiers

Although Quad's Solus is rated at 2x75W/8ohm with a 15A (microprocessor-controlled) current reserve, the casework quickly heats up under load – the heatsinks reaching 55oC after 30 minutes at just 10W/8ohm with distortion rising from 0.016% to 0.026%. So adequate ventilation is a must for the Artera Solus which, in practice, can deliver 2x84W/8ohm and 2x140W/4ohm with sufficient reserve for 105W, 197W, 303W and 170W into 8, 4, 2 and 1ohm loads [Graph 1]. This brings the maximum current closer to 13A for 1% THD over 10msec. Quad has designed the Solus for +30dB of overall gain which is far more sensible than the +40dB (or greater) still encountered in modern amps and ensures the baby Quad will offer good use of its volume control. Distortion, meanwhile, increases with level from 0.0045%/1W to 0.016%/10W and 0.1% at the rated 75W/8ohm (all 1kHz/8ohm) and with frequency up to 0.045%/20kHz. Noise is low and the A-wtd S/N generous at 90dB (re. 0dBW) while the response reaches deep and wide from 1Hz-60kHz ±1dB.

I discuss the choice of digital filters in our boxout [see Sidebar] although the 'Narrow' option seems to work optimally with CD rather than external LPCM inputs where there's a significant loss in treble. Via the coax/optical inputs the 'Smooth' filter delivers the flattest response and a significant 92dB stopband rejection. Otherwise, the A-wtd S/N is generous at 110dB (re. 2V balanced pre out) and distortion very low indeed, falling to 0.0002% over the top 30dB of its dynamic range [see Graph 2]. Jitter is impressively low at <15psec (24-bit data, all sample rates) and low-level linearity good to ±0.1dB over a 100dB dynamic range with both 24-bit digital inputs and via CD. PM

Continuous power (<1% THD, 8/4ohm): 84W / 140W
Dynamic power (<1% THD, 8/4/2/1ohm): 105W / 197W / 303W / 170W
Output impedance (20Hz–20kHz): 0.04–0.095ohm (116ohm, pre)
Freq. resp. (20Hz–20kHz/100kHz): +0.0 to –0.1dB/–2.55dB (Analogue)
Distortion (20Hz-20kHz, 0dBFs/0dBW) : 0.0012–0.0015%/0.016–0.045%
A-wtd S/N ratio (re. 0dBFs/0dBW): 109.5dB (Dig) / 89.6dB (Analogue)
Digital Jitter (CD / 48kHz/96kHz): 130psec / 15psec / 10psec
Power consumption (idle/rated o/p): 20W / 250W (1W, standby)
Dimensions (WHD / Weight): 320x105x320mm / 11.8kg
Price: £1500