Integrated Amplifiers

The core design and performance of the 600.2 integrated has closer parallels with the PRE/PAS pre/power [HFN Mar ’23], in turn inspired by the legacy Titan amplifier [HFN May ’10], than the beefier 800.2 integrated [HFN Aug ’23]. The 600.2 is a lower-powered (but not low powered!) version, rated at 160W/300W into 8/4ohm and delivering 200W/325W, respectively, but its low impedance drive is ‘restricted’ by the same protection regime we saw in the PAS but absent in the 800.2. Specifically, it will deliver 255W, 465W, 800W and 360W into 8, 4, 2 and 1ohm loads under dynamic conditions [see Graph 1], the PAS similarly limited to 575W/2ohm (17A) and 198W/1ohm, while the unrestricted 800.2 ploughs on to 1.30kW/2ohm and 2.20kW/1ohm (47A).

The 600.2’s overall gain (+36.8dB) is 6dB higher than the 800.2, and combined PRE/PAS gain, while the 88.9dB A-wtd S/N ratio falls between the 800.2’s 86.3dB and 94.1dB achieved by the PAS (all re. 0dBW). The response, meanwhile, is almost identical to that of the PRE/PAS – flat to 8Hz-52kHz within –1dB limits – and reaching out to 100kHz/–2.8dB. The output impedance is almost identical too, from 0.021-0.07ohm (20Hz-20kHz), increasing to 0.59ohm/100kHz. As we have seen with the earlier Nu-Vista amplifiers, distortion is low and very stable with both temperature (the 600.2 had spot temperatures of ~45oC after 10W/1 hour conditioning) and frequency. Versus level, distortion shows a very gentle increase from 0.0014%/1W to 0.002%/10W, 0.004%/100W and 0.005% at the rated 160W (all re. 1kHz/8ohm) while, versus frequency, there’s a relatively small increase to 0.001%/20Hz and 0.0035%/20kHz at 1W and 0.013%/20Hz and 0.0088%/20kHz at 100W [see Graph 2]. PM