Musical Fidelity Nu-Vista 300 power amplifier:
Measurements part 3
The Musical Fidelity's output power plotted against the THD+noise percentage, on continuous tones with both channels driven, is shown in fig.8. The amplifier clipped (defined as 1% THD+N) at 305Wpc into 8 ohms (24.8dBW), with 480Wpc available into 4 ohms (23.8dBW) and 700W into 2 ohms (22.4dBW), the last two readings below the specified power. But it should be noted that, with this much power being delivered into the load, our lab's AC line voltage was drooping considerably. It was just 108V for the 2 ohm delivery, which will compromise the measured figure.

Fig.8 Musical Fidelity Nu-Vista 300, distortion (%) vs continuous output power into (from bottom to top) 8 ohms, 4 ohms, and 2 ohms.

With just one channel driven, and using the Miller Audio Research Amplifier Profiler---which uses a low-duty-cycle toneburst more typical of a music signal---the Nu-Vista 300 delivered 420W into 8 ohms (26.2dBW), 784W into 4 ohms, and 1358W into 2 ohms! This is shown graphically in fig.9. Note this graph's logarithmic scales, which I used because of the amplifier's very low distortion. Only into a 1 ohm load (green trace) did the Musical Fidelity stumble, with the clipping point dropping to 996W.

Fig.9 Musical Fidelity Nu-Vista 300, distortion (%) vs 1kHz burst output power into 8 ohms (black trace), 4 ohms (red), 2 ohms (blue), and 1 ohm (green).

It's fair to say that this amplifier will deliver more than enough low-distortion power into any loudspeaker you care to match it with.---John Atkinson