LABORATORY TEST REPORT
Readers interested in a full technical appraisal of the performance of the SA-KI Ruby Super Audio CD Player should continue on and read the LABORATORY REPORT published on the following pages. Readers should note that the results mentioned in the report, tabulated in performance charts and/or displayed using graphs and/or photographs should be construed as applying only to the specific sample tested.
Newport Test Labs measured the output voltage of the Marantz SA-KI Ruby as 1.9753-volts, for both the left and right channels… which means that the balance between the channels was absolutely perfect. I’d like to emphasise this, because it’s the first time I’ve ever seen this result from any type of component… there’s usually always a small difference, even if it’s in the order of 0.0001dB. But the Marantz SA-KI Ruby? Perfect!
Separation between the channels was outstandingly good at low and midrange frequencies, with Newport Test Labs measuring it as 118dB at 20Hz and 114dB at 1kHz. The Marantz SA-KI’s a result of 91dB at 20kHz is extremely good, and is far more than will ever be required at this frequency. Interchannel phase errors were also extremely low, just 0.01 degrees at 20Hz, 0.07 degrees at 1kHz and 1.32 degrees at 20kHz.
Newport Test Labs measured the frequency response of the SA-KI Ruby using a standard Philips test CD, and the result of this test is shown in Graph 12, for both Filter 1 (red trace) and Filter 2 (black trace). You can see that Filter 2 gives the flattest response, such that it’s only 0.6dB down at 20kHz, to give an overall normalised response of 20Hz to 20kHz ±0.3dB. Using Filter 1, the response still extends out to 20kHz, but is rolled off quite steeply above 3kHz so it’s more than 3dB down at 20kHz. What’s also notable is the exceptional flatness of the response over the majority of the audio band: it’s totally indistinguishable from the graph’s horizontal grid line. The only reason you know it’s there is because the trace ‘fills’ the spaces in that grid’s dotted line.
THD (Total Harmonic Distortion) was very low, irrespective of the test level used by Newport Test Labs. Graph 1 shows it at a recorded level of 0dB (thus the player’s maximum output) and you can see there are only four harmonics visible, a second at –106dB (0.0005%), a third at –100dB (0.001%), a fourth at –132dB (0.00002%) and a fifth at –122dB (0.00007%). This is a