Phono Preamplifiers

Tested via its balanced in/outs the Nu-Vista Vinyl 2 allows for four MM and four MC gain settings, each grouped in 3dB increments. The +40dB to +49dB MM range arrives at +40.5dB, +43.5dB, +46.0dB and +49.0dB, accommodating pick-ups rated between 3.6-9.4mV (re. 1kHz/5cm/sec) to deliver 0dBV from the Nu-Vista Vinyl 2. The MC gain options range from +60dB to +69dB (+60.4dB, +63.3dB, +65.9dB and +68.9dB, in practice) and will match cartridges over a useful 361-956µV specification. Higher and lower output MCs are still perfectly 'useable' at the +60dB and +69dB settings, of course, thanks to the consistent 71dB A-wtd S/N ratio (re. 500µV input) and generous overload limits of 21.8mV (+60dB gain) down to 7.9mV (+69dB gain) – equivalent to a margin of ~33dB relative to their respective sensitivities. The MM stage offers an overload margin of 27dB but this is still comfortably higher than the ~20dB target necessary to accommodate the fiercest of cuts without clipping.

The MM A-wtd S/N ratio is higher at 81.0dB (re. 5mV input), though still 10-15dB behind the 'quietest' of stages, but this is in part due to the very high gain required of the active stages to support a fully passive RIAA network. The latter is accurate to within ±0.2dB from 20Hz-20kHz, rolling off gently to –1.4dB/100kHz and –3dB/5Hz. The 'Mild' subsonic filter [dotted trace, Graph 1] adopts the IEC profile, rolling off below 100Hz to –3dB/25Hz and –6dB/15Hz while 'Standard' [dashed trace] has a +0.6dB lift at 25Hz with a ~3rd-order roll-off thereafter. Distortion, as we saw with the original Nu-Vista Vinyl [see boxout, p61] falls to as low as 0.00055% before increasing to 0.0065%/20kHz [see Graph 2], but even the worse-case figure is still ~1000x lower than that from the average MC pick-up! PM