Sony SCD-XA777ES multichannel SACD/CD player Measurements part 2
Fig.6 Sony SCD-XA777ES, left-channel departure from linearity, 16-bit CD data (2dB/vertical div.).
Fig.7 Sony SCD-XA777ES, waveform of undithered 1kHz sinewave at -90.31dBFS, 16-bit CD data.
The analog output-stage linearity was also superb, with only odd-order harmonics present in the player's output while it decoded a 50Hz tone at 0dBFS into a 600 ohm "torture" load (fig.8)—and these are all below -100dB (0.001%)! Even with the punishing mix of full-scale 19kHz and 20kHz tones into the same load (fig.9), any intermodulation products stayed below the same -100dB.
Fig.8 Sony SCD-XA777ES, spectrum of 50Hz sinewave, DC-1kHz, at 0dBFS into 600 ohms (linear frequency scale).
Fig.9 Sony SCD-XA777ES, spectrum of 50Hz sinewave, DC-1kHz, at 0dBFS into 600 ohms (linear frequency scale).
Word-clock jitter with CD data, assessed using the Miller Audio Research Analyzer, was a superbly low 171 picoseconds peak-peak. A high-resolution spectral analysis of the Sony's analog noise floor while it played back the diagnostic jitter signal is shown in fig.10: the central peak, representing the 11.025kHz tone, is narrow (ie, free from random low-frequency jitter), the noise floor is virtually free from hashy spikes, and the data-related sidebands (indicated with red numeric markers) are all below -120dB. The highest-level sidebands, in fact, lie at ±600Hz (blue "4" markers, also circled in blue) and contribute 73ps to the total.
Fig.10 Sony SCD-XA777ES, high-resolution jitter spectrum of analog output signal (11.025kHz at -6dBFS with LSB toggled at 229Hz). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. Grayed-out trace is similar analysis for 11.025kHz tone (no LF LSB toggling) from SACD.
The only anomaly to be seen in this graph is the grayed-out trace, which is a similar analysis made of the '777's output while it decoded an 11.025kHz tone from SACD. The noise floor is free from any spuriae, but is also 10dB higher than that from CD, which is considerably more than I would have expected from figs.4 and 5. I repeated this measurement a number of times, only to get the same result each time.
Like other Sony SACD players reviewed in Stereophile, the SCD-XA777ES is almost beyond reproach. But I would like to have seen fewer magnetically induced power-supply spuriae in the analog output, even though these are almost certainly still too low to have any audible consequences.—John Atkinson