Article Index
Naim NAC N172 XS
p2 NAP 155XS power amp
p3 Jon Myles says
p4 Conclusion
p5 Measured Performance
All Pages

The preamplifier has a useful x5 gain (14dB), that translates back to an input sensitivity of 200mV for 1V output to a power amplifier – enough to drive most power amps to full output. Frequency response measured 4Hz- 59kHz – adequately wide, especially by Naim standards as they commonly bandwidth limit their power amps to 22kHz. It overloads at 9V output, a normal enough figure.
    Frequency response through the electrical S/PDIF inputs reached just 24kHz (-1dB) with a 192kHz sample rate S/PDIF input, our analysis shows. A figure of around 35kHz is common and the hard upper limit is 96kHz, so this figure is low, but it is within Naim’s philosophy of bandwidth limiting.
    The optical S/PDIF worked reliably up to 96kHz sample rate and frequency response was identical to that for 192kHz sample rate, the upper -1dB limit being 24kHz and the -3dB limit 30kHz.
    This result also applied to USB when playing 24/96 wav files from a memory key, and when reading the same files from a computer via ethernet. Both USB and Ethernet were a little noisier than S/PDIF but the Naim was, all the same, quieter than most rivals, with a -98dB noise floor, IEC A weighted.
    Distortion at -60dB via S/PDIF measured 0.21% with a 16bit signal and 0.06% with a 24bit signal, both low values for the resolution available, although 24bit can manage 0.02% and noise raised the Naim value a trifle. All inputs gave this result. EIAJ Dynamic Range values were 102dB (good) for 16bit and 108dB for 24bit (fair).
    Naim use good quality, low noise receiver chips in their network products, including the NAC-N 172 XS digital preamp tested here. It yields excellent results. But Naim have chosen to bandwidth limit this preamp’s digital inputs to 24kHz (-1dB) even at 192kHz sample rate where 96kHz of analogue bandwidth is theoretically available.  This is in line with their power amps though, which are also bandwidth limited to 24kHz . It maintains the Naim warm, smooth top end. NK

Frequency response (-1dB)                4Hz-59kHz
Gain    x5 (14dB)
Overload    9V out

S/PDIF / USB / Ethernet
Frequency response (-1dB)
192k sample rate    4Hz - 24kHz
Distortion (16/24bit)    %    0dB    0.04 / 0.04
-60dB    0.21 / 0.06
Separation (1kHz)     112dB
Noise USB (IEC A)    -98dB
Dynamic range    102 / 108dB
Output    9V max






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