Integrated Amplifiers

Bearing in mind the original Uniti Nova’s [HFN Nov ’17] 80W Class A/B amplifier has been replaced by a 150W-rated Class D variant in the ‘Power Edition’, many of its technical hallmarks are entirely retained. For example, overall gain is still a high +43dB and the A-wtd S/N ratio still below average at 79dB (re. 0dBW) while the frequency response is determined by Naim’s proprietary minimum phase brickwall IIR filter that delivers a 60th-order roll-off at 25kHz. In practice, analogue inputs are sampled at 48kHz, offering a system response of –1.5dB/20kHz and –9dB/24kHz (all 10W/8ohm), while the digital inputs extend to –1.1dB/20kHz and –14dB/30kHz (line output) with all incoming sample rates above 88.2kHz. Importantly this Class D amp’s response is not load-dependent, its output impedance retained at a moderately high but ruler-flat 0.163-0.165ohm.

The Uniti Nova managed 2x96W/8ohm and 2x155W/4ohm, with 114W, 190W, 290W and 165W into 8, 4, 2 and 1ohm under dynamic conditions. By contrast this ‘Power Edition’ also busts its modest (150W) specification with 190W/8ohm and 330W/4ohm, and 243W, 456W, 603W and 350W into 8, 4, 2 and 1ohm loads under dynamic conditions [see Graph 1]. So the ‘PE’ will not only achieve high levels, it will also drive tougher loudspeaker loads. Distortion drops to a minimum of 0.0025-0.0065% at 10W/8ohm (20Hz-20kHz) while, tested at a 2.1V line output level, the Nova PE’s PCM1791-based DAC stage retains its modest 103dB A-wtd S/N ratio while distortion drops to a minimum of 0.0005-0.0018% at –25dBFs [Graph 2], increasing to 0.0085-0.035% with a 0dBFs digital input (all 20Hz-20kHz). Jitter is an infinitesimal <5psec with all incoming sample rates. PM