Sony SCD-XA777ES multichannel SACD/CD player Measurements

Sidebar 3: Measurements

The measurements were all performed from the SCD-XA777ES's front left and right output jacks, which benefit from the paralleled DAC chips. The Sony's maximum output level from SACD was 2.02V, which was a little higher (0.26dB) than from CD. Be warned: This will be audible in A/B comparisons, and will favor the hi-rez format. The output impedance was a low 110 ohms across most of the audioband, rising inconsequentially to 132 ohms, and the player preserved absolute polarity. Error correction was superb—the Sony played the Pierre Verany test CD without glitches to track 35, which has 2.4mm gaps in its data spiral.

With the Standard filter, the frequency response from CD (fig.1, top two traces) and from SACD (fig.2) was flat across the audioband, with the SACD response down 3dB at 50kHz. With pre-emphasized CD data (fig.1, lower traces), a slight shelving-down appeared in the top audio octave, but this will probably be inaudible. Channel separation (fig.3) was superb overall, at better than 110dB in the midrange and low treble, but decreased a little at low and high frequencies.

Fig.1 Sony SCD-XA777ES, CD frequency response at -12dBFS, without emphasis (top) and with emphasis (bottom). (Right channel dashed, 0.5dB/vertical div.)

Fig.2 Sony SCD-XA777ES, SACD frequency response at -3dBFS (right channel dashed, 2dB/vertical div.).

Fig.3 Sony SCD-XA777ES, channel separation ref. 0dBFS (10dB/vertical div.).

Fig.4 shows a 1/3-octave spectral analysis of the Sony's noise floor while it played back data representing a dithered 1kHz tone at -90dBFS. The upper two traces in this graph are from CD data, the lower two from SACD. The hi-rez format has a noise floor generally about 10dB lower than that from CD, but this is disturbed by the presence of noise spikes at the 60Hz AC mains frequency and its odd harmonics, most likely due to magnetic interference from the power transformer. Above 11kHz, SACD has less dynamic range than CD, due to the format's aggressive noise-shaping, but I don't believe this is subjectively significant. This ultrasonic noise can also be seen in fig.5, which shows similar but wider-band spectral analyses with the '777ES playing back "digital black" from the two media.

Fig.4 Sony SCD-XA777ES, 1/3-octave spectrum of dithered 1kHz tone at -90dBFS, with noise and spuriae (from top to bottom): 16-bit CD data, DSD SACD data (right channel dashed).

Fig.5 Sony SCD-XA777ES, 1/3-octave spectrum of digital black (from top to bottom above 10kHz): DSD SACD data, 16-bit CD data (right channel dashed).

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