Pre/Power Amplifiers

True to tradition, and despite being a Class D amp, NAD has engineered some useful headroom into the C 298 which supports peaks of 265W, 526W and 750W into 8, 4 and 2ohm loads with 450W/1ohm limited by current protection (21.2A). Note how there is no abrupt clipping point but, instead, maximum power is 'feathered' across 40W of 'extra' output as it approaches 1% THD into 8/4ohm loads [see Graph 1, below]. This is the modern-day equivalent of NAD's 'Soft Clipping'.

Otherwise, the continuous 235W/8ohm and 475W/4ohm power output is well in excess of NAD's 185W/8ohm and 340W/4ohm rated spec. for the C 298 – this conservative 'paper spec' is good to see, particularly as many Class D amplifiers seem rated very close to the wire these days. Bottom line? The NAD C 298 will go louder and prove more capable of driving difficult speakers than you might expect. The very low sub-5mohm output impedance will also assist in keeping bass tight while ensuring the C 298's response – flat to within ±0.04dB/20Hz-20kHz – is unaffected by swings in speaker impedance.

Distortion is fabulously low through bass and midrange frequencies at 0.0004%/1W, 0.0002%/10W and 0.0006%/100W, the inevitable rise at HF delayed here to above 10kHz, albeit only reaching a mere 0.003%/1W, 0.0065%/10W and 0.030%/100W at 20kHz [see Graph 2, below]. Again, these Purifi Eigentakt modules buck the trend of more traditional Class D solutions whose high frequency response and distortion are markedly influenced by speaker load [see HFN Aug '21]. Noise, too, is lower here than typical, the C 298 yielding a respectable 88.1dB A-wtd S/N ratio (re. 0dBW) for an overall gain of +28.7dB. PM