Integrated Amplifiers

Tested via its analogue line input, the C 3050 LE's power output and distortion depend on the position of the volume control because the input ADC (sampling at 48kHz) can clip before the output. The frequency response is also limited to 23kHz (re. –3dB) unless the amp is used via its 'Main In' RCAs which route directly to Hypex's analogue UcD102 v1 Class D module. Bypassing the ADC/DAC and volume control, the C 3050 LE's overall gain ends up fractionally higher at +29.1dB (from +28.6dB), the A-wtd S/N improves from 78.7dB to 81.5dB (re. 0dBW) and the response stretches smoothly out to 48kHz/–1dB and 100kHz/–5.3dB. The consistently low 0.035ohm output impedance (20Hz-20kHz) and load tolerance of the Hypex modules has already been well documented in HFN Lab Reports, NAD squeezing a full 2x120W/8ohm and 2x200W/4ohm from the UcD102 here with enough headroom 'engineered in' to yield 139W/8ohm and 275W/4ohm under dynamic conditions [see Graph 1]. Output is limited to 252W/2ohm and 201W/1ohm by NAD's fast-acting protection (the bright red meter illumination is quite a show!).

The digital performance is in part determined by the TI PCM5242 DAC, implemented here with a standard linear phase filter offering a modest 44dB of stopband rejection and a response (via the pre outs) that reaches out to –0.07dB/20kHz, –0.7dB/45kHz and –1.8dB/90kHz with 48kHz, 96kHz and 192kHz media, respectively. The A-wtd S/N ratio is a respectable 108dB and low-level linearity is good to within ±0.2dB over a 100dB dynamic range while THD falls to as low as 0.0005-0.004% (20Hz-20kHz, –10dBFs). Correlated jitter is a low ~10psec but a more significant uncorrelated phase noise was seen on test. PM