Sony CDP-XA7ES CD player Measurements

Sidebar 3: Measurements

I suppose it's inevitable that when you measure a lot of audio gear, you tend to look at things a little differently from those who don't. I tend to be a little put off by products that either measure well but sound bad or sound good but measure poorly. I like consistency in my audio equipment, and am most impressed by equipment that shines across the board.

With one exception, the Sony CDP-XA7ES looked so good on the test bench that I'd like to just limit this section to: "Measures great. Go for it." For those of you who insist on more, the details are presented below. Otherwise, there just isn't much to be said about this level of performance.

The Sony's DC offset was negligible at a measured 2mV in the left channel, 1.7mV in the right. In the unbalanced mode (fixed outputs), the maximum output was 2.6V (2.7V, or essentially the same, balanced). The left and right channels were within 11mV of each other. The output impedance from the unbalanced fixed outputs was 99.5 ohms in the left channel, 128 ohms in the right. The corresponding values for the transformer-coupled balanced outputs were 290.5 ohms and 292 ohms, respectively. At the variable outputs, the output impedance was 195 ohms.

The remainder of the measurements were taken at the unbalanced, fixed outputs, from which I had done most of my auditioning. I did check the frequency response from the balanced outputs, and found it virtually identical to the unbalanced result. The latter, together with the de-emphasis error, is plotted in fig.1. No comment necessary here. The channel separation is shown in fig.2. While the crosstalk is not the lowest we've encountered in a single-box CD player, it's certainly no limitation on the Sony's performance.

Fig.1 Sony CDP-XA7ES, frequency response (top) and de-emphasis response (bottom) (right channel dashed, 0.5dB/vertical div.).

Fig.2 Sony CDP-XA7ES, crosstalk (R–L channel dashed, 10dB/vertical div.).

The 1/3-octave spectral analysis of a 1kHz, –90dB dithered sinewave (fig.3) is nearly ideal, with extremely low power-supply noise and no discrete harmonics visible. The same can be said of the wideband spectral analysis of a silent track (all zeros) in fig.4. The noise floor here is extremely low; the increased noise at higher frequencies is due to the noise-shaping typically used to obtain sufficient resolution from low-bit DACs.

Fig.3 Sony CDP-XA7ES, spectrum of dithered 1kHz tone at –90.31dBFS, with noise and spuriae (16-bit data, 1/3-octave analysis, right channel dashed).

Fig.4 Sony CDP-XA7ES, spectrum of digital silence (16-bit data, 1/3-octave analysis, right channel dashed).

The linearity of the left channel of the CDP-XA7ES is shown in fig.5. I have not seen better. The right channel, not shown, was essentially the same. The Sony produced a nearly ideal stairstep waveform when processing a 1kHz, –90.31dB undithered sinewave (fig.6). The symmetry is superb, the noise low. And, finally, the artifacts present from a 19+20kHz waveform (fig.7) are all below –90dB (0.003%).

Fig.5 Sony CDP-XA7ES, departure from linearity (left channel dashed, 2dB/vertical div.).

Fig.6 Sony CDP-XA7ES, waveform of undithered 1kHz sinewave at –90.31dBFS (16-bit data).

Fig.7 Sony CDP-XA7ES, HF intermodulation spectrum, DC–24kHz, 19+20kHz at 0dBFS (linear frequency scale, 20dB/vertical div., 0dB = –6dBFS).

Because of the CDP-XA7ES's internal layout, it wasn't possible—short of a self-defeating partial disassembly—to access the points of the digital circuitry required to measure the player's jitter performance; therefore, I didn't make our usual jitter tests.

The only result that was less than exceptional was the CDP-XA7ES's tracking performance, as tested using the Pierre Verany Test CD. Skipping began on track 30—a decidedly mediocre result. While I experienced no tracking problems in normal use, problems might be encountered with scratched discs.—Thomas J. Norton

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