Marantz SA-KI/PM-KI Ruby SACD Player/Amplifier Lab Report

Lab Report

Although the PM-KI Ruby uses the same Ncore NC500 Class D amp module found in the PM-10 [HFN Aug '17] its single-ended implementation here yields subtle differences in performance. Once again, Marantz's power specification proves to be very conservative as its 100/200W 8/4ohm rating is bested to the tune of 170W/280W in practice, with 200W, 360W, 610W and 370W achieved under dynamic conditions into 8, 4, 2 and 1ohm loads [see Graph 1, below]. So while the PM-KI Ruby's 8/4ohm output is only a third that of the PM-10, its ability to drive very low impedance speakers is actually superior. On the other hand, without bridged operation, distortion is slightly higher – especially at high frequencies (0.03% vs. 0.12% at 20kHz/0dBW) – and the A-wtd S/N rather poorer at 80dB vs. 91dB (both re. 0dBW). Once again, however, the response remains unaffected by loading and is almost identical to that of the PM-10, reaching out to –0.6dB/20kHz and –6.3dB/100kHz.

319marantzsacd.fig1

Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 19.2A

319marantzsacd.fig2

Distortion versus digital signal level at 1kHz (S/PDIF/USB, red; CD, black) and 20kHz (CD, blue)

Marantz's partnering SA-KI Ruby player offers a 1.99V analogue output with a modest 102dB A-wtd S/N ratio and distortion that's just 0.0002-0.00025% (20Hz-20kHz) with Filter 1 [see Graph 2] and fractionally higher at 0.0005% with Filter 2. The response (and stopband rejection) depends on your choice of digital filter: 'Filter 1' is a slow roll-off type with minimal pre/post ringing that offers a mere 4.1dB image rejection and a roll-off of –4.9dB and –3.8dB/20kHz (CD/48kHz files), –7.6dB/45kHz (96kHz files) and –21dB/90kHz (192kHz files). 'Filter 2' has more post-event ringing with a slightly 'flatter' –1.5dB/20kHz, –5.2dB/45kHz and –15dB/90kHz response. Jitter is low with 24-bit LPCM sources at 65psec and just 25psec with SACD. PM

Continuous power (<1% THD, 8/4ohm) 170W / 280W
Dynamic power (<1% THD, 8/4/2/1ohm) 200W / 360W / 610W / 370W
Freq. resp. (20Hz-20kHz/100kHz) +0.0 to –0.60dB/–6.3dB
Freq. resp. (20Hz-20kHz, Filter 1/2) +0.0 to –4.9dB/–1.5dB
Digital jitter (CD / USB / SACD) 125psec / 65psec / 25psec
A-wtd S/N ratio (Player/Amp) 102.1dB (0dBFs) / 79.6dB (0dBW)
Distortion (20Hz-20kHz; Player/Amp) 0.0002-0.0003%/0.0019–0.12%
Power consumption (Player/Amp) 27W / 255W (33W idle)
Dimensions (WHD, Player/Amp) 440x127x419/440x127x453mm
Price £3500 (each)
COMPANY INFO
Sound United
Shirakawa, Japan
Supplied by: D&M Audiovisual Ltd, UK
02890 279830
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