Hello to everyone.
This is a review and test of the Sony SCD-XA9000ES SACD and CD player. It was released in 2003 and cost $3000 at the time. A new version having a marginally modified optical pick-up and servo board and a unique silver finish was released only for the European market area at the end of the year 2005.
Part I: Presentation
The Sony SCD-XA9000ES is a multichannel and stereo SACD and CD player.
It gets an "i.Link" (Firewire) digital output for DSD data or CD data and regular S/PDIF and Toslink digital outs for CD data only. There is one set of 6 RCA (unbalanced) outputs for up to 5.1 SACD replay and one additional pair of RCA outputs for 2 channels replay. Although the front Left and Right channels of the 5.1 output work simultaneously to the 2 channels output when stereo materials (be them SACDs or CDs) are played back, there is a key difference between the two sets of output. Indeed, Sony chose to take the hassle of paralleling all available six channels DAC and output stages to get a lower noise floor at the 2 channels output. Two pictures out of the Sony White Paper applicable to the SCD-XA9000ES put side-by-side show this system, nicknamed "Tri-Power DAC":
On figure 1, the term "SADAC" refers to the DAC chip (SADAC means "Super Audio DAC" according to Sony). This DAC chips bear a Sony part number, CX9657, but is was understood very early that this chip is related to the Burr Brown PCM1738 (more on that latter in the review). As can be seen, the DACs are used in monaural mode in a dual differential configuration. What is not shown on the picture is the fact that it isn't the DACs alone that are paralleled in the Tri-Power DAC mode of operation, but indeed the DACs and their respective whole analogue conditioning stages: current to voltage converters, output low-pass filters and output buffers. The output of those circuits are summed together through a resistor bus at the input of an active mixer followed by another buffer output stage. Thus, there is a great deal of analogue processing at work in the Tri-Power DAC mode. That should limit somehow the expected improvement of the signal to noise ratio.
There is also a front phone output jack with volume control.
The Sony SCD-XA9000ES offers 2 different digital interpolation filters for CD data. For SACD playback, the player is able to do channel level trimming, bass redirection (including a 2 channels to 2 channels+subwoofer mode) and speakers time alignment.
My user experience is excellent. The drawer and traverse mechanism work smoothly and silently. All front controls are easy and pleasant to use thanks to the slanted front panel and the large wheel-knob which is used to navigate through disc contents and the well laid out configuration menus of the player, which are displayed on the lavish bevelled glass front screen. Compared to other players, the front panel lacks some useful information, though. Especially, the track calendar can only show a very limited number of tracks.
The build quality is impressively luxurious, both inside and outside the unit. Most of the case parts are made of thick aluminium pieces and the unit is very heavy.
The Sony plays all types of disc gapeless, but it is a bit on the slow side for indentifying disc types and reading the TOC. Over the years, many SCD-XA9000ES also suffered the sad fate that their optical pick-ups have lost the ability to identify hybrid SACD/CD discs or to read SACDs altogether. Unfortunatly, mine has not escaped that fate: it not longer recognizes hybrid discs, which will prevent me to perform measurements with my few SACD test discs as these discs are all hybrids. But the player remains capable to play pure (non hybrid) single layerand dual layer SACDs and I will do few experiments with them. So keep in mind potential issues with SACDs when buying on the used market.
Let's get to the review !
I will do my best to adhere to the following general framework, when it is possible with the various test discs available to me:
1. Dashboard @ about 1 kHz, 0 dBFS
2. Frequency response related measurements
3. Noise and distortion related measurements
4. Linearity tests
5. Special tests
6. Disc readability tests
Part II: Measurements of the Sony SCD-XA9000ES as a CD Player
All measurements were taken with an Audio Precision System One+DSP SYS222A (nominal input impedance: 100 kohms in parallel with 170 pF). Unless otherwise stated, the tests were performed with NTTY’s Test CD Version 7.2. The Audio Precision has always been given the 30 minutes preconditioning period mandated in its calibration procedure and the device under test the 5 minutes mandated by the AES-17 standard.
1. Dashboards
As said earlier, the Sony SCD-XA9000ES gets 2 interpolation filters to choose from. Unless otherwise noted, all measurements below are performed with the "Standard" digital filter, as well as from the 2 channels output (Tri-Power DAC mode) which should be the way most people use this disc player.
Keep in mind that the old Audio Precision System One has no dual analogue to digital converter per analyzer channel, hence cannot display a recombined representation of both the test signal and the distortion residual. Contrary to Amirm's reviews, you will only see the distortion residual with a “notch” on each side of the leftover of the test signal: this is where the analyzer band-reject filter has removed the test tone prior to the digitization and measurement of the residual signal.
The output level is not consistent and depends on the chosen output. From a CD, it is in the vicinity of 1.9 V RMS at the front channels of the 5.1 output and 1.8 V RMS (0.5 dB less) at the 2 channels outputs. About SACD, I can report that Stereophile and the Italian magazine Audioreview had measured about 2 V RMS at the front channels of the 5.1 output, and 1.9 V RMS (0.45 dB less) at the 2 channels outputs. So, beware of those facts when trying to compare CD and SACD with this player.
The dashboards from the 2 channels output show excellent performance for a CD player. The levels of the two channels are matched only within 0.11 dB, though, which is good rather than great for a player of this caliber but stay under the threshold of audibility, I guess.
The mean SINAD of 97.4 dB is actually dominated by noise. The harmonic distortion spectra of the two channels are consistent with measurements made by a German laboratory in 2003 in SACD mode and that I have reported elsewhere.
Here are dashboards with the optional digital filter:
The measured THD+N (inverse of SINAD) is a bit better just because this digital filter rolls off some noise at high frequencies, but apart from that, the distortion pattern remains the same. A good point is that the optional digital filter keeps the output level the same as the standard filter.
Finally, here are the dashboards from the front Left and Right channels of the 5.1 output to compare to the above:
No change in distortion. The only differences are the output level (the 2 channels are a bit better matched at about 0.08 dB) and slightly more noise that degrades the THD+N despite the higher level of the signal.
To comply with the practice set by NTTY in his exceptionally thorough CD player reviews, here are dashboards of the 2 channels output at -6 dBFS:
At -6 dBFS, the respective THD+N (inverse of SINAD) of the two channels are almost the same and are noise dominated. The channel imbalance at this level remains the same as at 0 dBFS.
2. Frequency response
Let's see how the two available interpolation filters of the Sony act on the player’s frequency response in a high resolution analysis. The two following measurements have been made with a glide tone at -15 dBFS from the Denon Audio Technical CD:
The frequency response with the standard digital filter (cyan and yellow traces) is flat to about 0.15 dB in the audio band, whereas the optional digital filter rolls of the high frequencies earlier (red and green traces). Please note the perfect match in level between the two digital filters, until the higher roll-off rate of the optional filter kicks in around 14 kHz. None of the two filters significantly alters the interchannel phase.
Another way to look at the effect of the digital filters is to trace the wideband response with white noise up to ultrasonic frequencies (in this case 85 kHz):
The SCD-XA9000ES decodes emphasized tones at -20 dBFS from the Stereophile Test CD2 at almost correct levels:
Cross-checking with emphasized data at -10 dBFS from the HiFi-News and Record Review Test CD II (HFN 015) has demonstrated similarly correct results (not shown).
Crosstalk evaluated with spot tones from the Denon Audio Technical CD shows that there is a slight penalty to use the Tri-Power DAC mode, presumably because of the more complex signal path, but it is good in any case:
3. Noise and distortion measurements
Let's start with some Left/Right single point measurements about noise and distortion before proceeding with more graphs. All measurements are done with standard Audio Precision tests:
I apologize for the complexity of the table, but had many combinations to test and had to find a way to express the results.
The signal to noise ratio is consistent with the dynamic range. That indicates that the DACs does not mute their outputs when they are fed with a digital signal containing only zeros. The reason why the signal to noise ratio is greater than the dynamic range is because a digital signal containing only zeros does not exercise any quantization level above or below the 0 level, hence no quantization noise is generated at the output of the DAC.
The Tri-Power DAC mode consistently gives about 1.1 to 1.5 dB better signal to noise ratio compared to the front Left and Right channels of the 5.1 output, but the dynamic range and quantization noise are almost the same. The Tri-Power DAC mode is thus efficient on the analogue noise, but less so on the noise generated by the digital processing, which sets the limit of performance. Accordingly, the Tri-Power DAC mode must be more useful with stereo SACD replay than CD replay, because the very nature of DSD is to reject from the audio band the quantization noise that comes from the digital processing.
Paralleling the DACs and output stages seems to have no effects on intermodulation distortion, the largest discrepancies being with the 0 dBFS DIN IMD test and even in that case, the differences remain very low.
Likewise, choosing the optional digital filter does not make a significant difference with the various type of intermodulation signal, except with twin high frequencies of 19 and 20 kHz. So, in any case, the two digital filters implemented by Sony manage to keep things well in control in the audio band.
The resistance of the Sony SCD-XA9000ES to intersample overs is impressive. It is a behavior I had previously reported here. This is all the more interesting that the Pioneer DV-868AVi I have also reviewed showed no resistance to intersample overs whereas it uses Burr Brown PCM1738 DACs that are thought to be identical to the Sony CXD9657, as already stated. So either Sony managed to drive the DACs in a way to avoid clipping at the interpolation stage or the two chips are indeed not entirely identical and there are actually differences in the interpolation stage. At any rate, it may be be that here we get a champion of the league on the matter of intersample over.
To go further in the analysis, Audio Precision provides some standard tests to assess the noise performance of a CD player.
First test is to look at the FFT spectrum of an “Infinity Zero” signal from the Denon Audio Technical CD up to 80 kHz:
Please take into consideration than this measurement is free from any influence of the digital processing since the test signal contains only zeros. It only shows the analogue components of the noise. Here is the same test but from the front Lef and Right channels of the 5.1 output (that is, the no Tri-Power DAC mode):
The level of the noise floor and of the two small high frequency spurious tones are indeed slightly higher. By the way, the higher of the two spurious tone is at about 44 kHz: it may be related to the CD data clock.
A variation of this test suggested by Audio Precision is to restrict the measurement bandwidth to the low frequencies and to lower the sample rate in order to narrow the bin frequency width. That way, it is possible to search for mains frequency interference and power supply related noise with great resolution. First, with the Tri-Power DAC mode:
Second, at the front Left and Right channels of the 5.1 outputs, which show slightly higher noise floor and power supply spurious:
The other tests use the analogue analyzer to plot 1/3 octave curves of the noise with the same "Infinity Zero" signal. Although this method has less frequency resolution than the FFT analysis (the higher the frequency, the wider the noise bandwidth that each point of the curve represents contrary to an FFT analysis where each “bin” has equal bandwidth; that is why the curve obtained with the analogue analyzer regularly increases towards higher frequencies), it takes advantage of the greater dynamic range and the wider frequency response of the Audio Precision System One’s analogue analyzer over its ADCs.
The same test restricted to the audio bandwidth will be useful to compare to a special test that will be shown below:
Lastly, I add a test inspired by NTTY's practice to show an FFT spectrum up to 1 kHz when the player is reproducing a 1 kHz tone at 0 dBFS in search of power supply spurious noise. For this test, I set up an FFT at 8 ksps in order to improve bin frequency resolution to look after the output of the notch filter. Here I have to make a choice about which signal to use. I have chosen the 999.91 Hz sine with noise-shaped dither, which produces the lowest noise floor. All the spurious tones remain well under -130 dBr, thus benign:
THD+N vs frequency was assessed with spot tones at 0 dBFS without dither from the Pierre Vérany Digital Test CD. First within a 20 kHz bandwidth (i.e. the audio band):
There is no increase in distortion in the bass. With the standard digital filter (solid curves), the THD+N towards the high frequencies shows a tendency to go downward, a clue that the distortion pattern is constant with frequency as the upper harmonics move out of the analysis bandwidth. The sharp downward slope of the curve above 10 kHz is due to the fact that the second harmonic at 10 kHz and above falls outside the pass-band of the test, hence there is no longer any harmonic to measure, only noise. In fact, I had to expand a little the bottom of the vertical scale, because the curve of the right channels goes just under 0.001%. The upward curve from about 15 kHz most probably indicates an increase in the noise (including quantization noise) or distortion due to imaging above the 22.05 kHz Nyquist frequency of CD folding back into the audio band when the player has to reproduce high frequencies at high level. The optional digital filter (dashed curves) shows a sharp increase in THD+N above 13 kHz due to bleeding of imaging distortion in the audio band, an inescapable side effect of insufficient low-pass filtering above the Nyquist frequency, as is visible above with white noise. But at 0.05% (-66 dB) worst case at 20 kHz, the THD+N remains small nonetheless.
Second, here is the same test, but with a wider measurement bandwidth up to 80 kHz (standard digital filter only):
The increase of THD+N at higher frequencies is kept low by any measure, which is a very good result in my book.
The same measurement made with the optional digital filter shows a different picture:
The THD+N goes to the roof, mostly because the image of the test signal above the Nyquist frequency (22.05 kHz) is not suppressed by the digital filter. So better to use this digital filter when the frequency bandwidth of the musical signal is known to be within a 10 kHz or so bandwidth.
THD+N in function of levels has also been assessed (only with the standard digital filter) with the help the 999.91 Hz test signals from NTTY CD test disc. First with dithered tones (which gives a typical performance curve, because CD production is almost universally done with dither), and then with undithered tones (to see a truer picture of the level of performance of the player):
With dither, the curves remains almost flat up to 0 dBFS, which shows that the THD+N is dominated by the dither noise, not distortion. Without dither, the two curves stay at or below -98 dB THD+N up to -5 dBFS level or so. That means that the Sony SCD-XA9000ES is capable of 16 bits accuracy over almost a 65 dB wide dynamic range, and above -5 dBFS, little excess noise or distortion begin to appear.
Audio Precision provides a standard test to evaluate more qualitatively the SMPTE intermodulation distortion by looking at the digitization of the output of the analogue analyzer filter that removes the 60 Hz and 7 kHz tones to observe the actual distortion products:
The same test conducted with the optional digital filter shows an identical result (not shown).
The old 16 bits Burr Brown PCM78 ADCs of the Audio Precision System One probably limits the usefulness of FFTs of high level CCIF twin tone signals, because of the high dynamic of this signal relative to the noise floor. Here is an FFT of a -3.02 dBFS twin tones in a 23 kHz bandwidth:
Pairs of odd order distortion products (at 18 and 21 kHz, 17 and 22 kHz and 16 and 23 kHz) are visible, the highest pair being at about 90 dB under the level of each twin tones. The even order distortion at 1 kHz is some 105 dB under the level of each twin tones, which is very low.
The same test performed with the optional digital filter shows similarly good results, but, interrestingly, splitting of some intermodulation products and of the image of the 19 kHz tone at 23 kHz is noticeable:
Wideband analysis of this same CCIF test signal are also interresting:
The second graph shows that although very significant images of the twin tones are left above the Nyquist frequency, the suppression of the optional filter above 30 kHz is very good indeed.
For the same reason already explained about the dynamic range of the old Audio Precision ADCs, I do not think an FFT of the multitone signal from NTTY's test CD can give much detailed information. Moreover, the maximum FFT length that the System One is capable of restricts the bin frequency resolution in the bass. Anyway, here is the FFT spectrum of such signal, but from 100 Hz only:
4. Linearity Tests
With the kind help of NTTY, who has created a custom linearity test track with noise-shaped dithered spot tones down to -130 dBFS, I am able to assess the player's DAC deviation from linearity with the System One's software-implemented selective voltmeter:
I have used the same scale than the one Amirm uses for its own tests to ease comparison. The yellow curve (right channel) stops at -100 dBFS because the right channel of the Audio Precision was unable to settle to any reading under that level. The player's output deviates significantly from linearity somewhere between -110 dBFS and -120 dBFS, where the error is at +0.6 dB. This is roughly 18.5 bits of accuracy.
I made an FFT analysis of the -130 dBFS sine signals which shows better results at this very low level, presumably thanks to the effects of the averaging, which is not a component of the above linearity test:
That means that the players tends towards the correct level even at that low a level when the signal is sustained long enough to be observed.
(To be continued in message #2)
This is a review and test of the Sony SCD-XA9000ES SACD and CD player. It was released in 2003 and cost $3000 at the time. A new version having a marginally modified optical pick-up and servo board and a unique silver finish was released only for the European market area at the end of the year 2005.
Part I: Presentation
The Sony SCD-XA9000ES is a multichannel and stereo SACD and CD player.
It gets an "i.Link" (Firewire) digital output for DSD data or CD data and regular S/PDIF and Toslink digital outs for CD data only. There is one set of 6 RCA (unbalanced) outputs for up to 5.1 SACD replay and one additional pair of RCA outputs for 2 channels replay. Although the front Left and Right channels of the 5.1 output work simultaneously to the 2 channels output when stereo materials (be them SACDs or CDs) are played back, there is a key difference between the two sets of output. Indeed, Sony chose to take the hassle of paralleling all available six channels DAC and output stages to get a lower noise floor at the 2 channels output. Two pictures out of the Sony White Paper applicable to the SCD-XA9000ES put side-by-side show this system, nicknamed "Tri-Power DAC":
On figure 1, the term "SADAC" refers to the DAC chip (SADAC means "Super Audio DAC" according to Sony). This DAC chips bear a Sony part number, CX9657, but is was understood very early that this chip is related to the Burr Brown PCM1738 (more on that latter in the review). As can be seen, the DACs are used in monaural mode in a dual differential configuration. What is not shown on the picture is the fact that it isn't the DACs alone that are paralleled in the Tri-Power DAC mode of operation, but indeed the DACs and their respective whole analogue conditioning stages: current to voltage converters, output low-pass filters and output buffers. The output of those circuits are summed together through a resistor bus at the input of an active mixer followed by another buffer output stage. Thus, there is a great deal of analogue processing at work in the Tri-Power DAC mode. That should limit somehow the expected improvement of the signal to noise ratio.
There is also a front phone output jack with volume control.
The Sony SCD-XA9000ES offers 2 different digital interpolation filters for CD data. For SACD playback, the player is able to do channel level trimming, bass redirection (including a 2 channels to 2 channels+subwoofer mode) and speakers time alignment.
My user experience is excellent. The drawer and traverse mechanism work smoothly and silently. All front controls are easy and pleasant to use thanks to the slanted front panel and the large wheel-knob which is used to navigate through disc contents and the well laid out configuration menus of the player, which are displayed on the lavish bevelled glass front screen. Compared to other players, the front panel lacks some useful information, though. Especially, the track calendar can only show a very limited number of tracks.
The build quality is impressively luxurious, both inside and outside the unit. Most of the case parts are made of thick aluminium pieces and the unit is very heavy.
The Sony plays all types of disc gapeless, but it is a bit on the slow side for indentifying disc types and reading the TOC. Over the years, many SCD-XA9000ES also suffered the sad fate that their optical pick-ups have lost the ability to identify hybrid SACD/CD discs or to read SACDs altogether. Unfortunatly, mine has not escaped that fate: it not longer recognizes hybrid discs, which will prevent me to perform measurements with my few SACD test discs as these discs are all hybrids. But the player remains capable to play pure (non hybrid) single layer
Let's get to the review !
I will do my best to adhere to the following general framework, when it is possible with the various test discs available to me:
1. Dashboard @ about 1 kHz, 0 dBFS
2. Frequency response related measurements
3. Noise and distortion related measurements
4. Linearity tests
5. Special tests
6. Disc readability tests
Part II: Measurements of the Sony SCD-XA9000ES as a CD Player
All measurements were taken with an Audio Precision System One+DSP SYS222A (nominal input impedance: 100 kohms in parallel with 170 pF). Unless otherwise stated, the tests were performed with NTTY’s Test CD Version 7.2. The Audio Precision has always been given the 30 minutes preconditioning period mandated in its calibration procedure and the device under test the 5 minutes mandated by the AES-17 standard.
1. Dashboards
As said earlier, the Sony SCD-XA9000ES gets 2 interpolation filters to choose from. Unless otherwise noted, all measurements below are performed with the "Standard" digital filter, as well as from the 2 channels output (Tri-Power DAC mode) which should be the way most people use this disc player.
Keep in mind that the old Audio Precision System One has no dual analogue to digital converter per analyzer channel, hence cannot display a recombined representation of both the test signal and the distortion residual. Contrary to Amirm's reviews, you will only see the distortion residual with a “notch” on each side of the leftover of the test signal: this is where the analyzer band-reject filter has removed the test tone prior to the digitization and measurement of the residual signal.
The output level is not consistent and depends on the chosen output. From a CD, it is in the vicinity of 1.9 V RMS at the front channels of the 5.1 output and 1.8 V RMS (0.5 dB less) at the 2 channels outputs. About SACD, I can report that Stereophile and the Italian magazine Audioreview had measured about 2 V RMS at the front channels of the 5.1 output, and 1.9 V RMS (0.45 dB less) at the 2 channels outputs. So, beware of those facts when trying to compare CD and SACD with this player.
The dashboards from the 2 channels output show excellent performance for a CD player. The levels of the two channels are matched only within 0.11 dB, though, which is good rather than great for a player of this caliber but stay under the threshold of audibility, I guess.
The mean SINAD of 97.4 dB is actually dominated by noise. The harmonic distortion spectra of the two channels are consistent with measurements made by a German laboratory in 2003 in SACD mode and that I have reported elsewhere.
Here are dashboards with the optional digital filter:
The measured THD+N (inverse of SINAD) is a bit better just because this digital filter rolls off some noise at high frequencies, but apart from that, the distortion pattern remains the same. A good point is that the optional digital filter keeps the output level the same as the standard filter.
Finally, here are the dashboards from the front Left and Right channels of the 5.1 output to compare to the above:
No change in distortion. The only differences are the output level (the 2 channels are a bit better matched at about 0.08 dB) and slightly more noise that degrades the THD+N despite the higher level of the signal.
To comply with the practice set by NTTY in his exceptionally thorough CD player reviews, here are dashboards of the 2 channels output at -6 dBFS:
At -6 dBFS, the respective THD+N (inverse of SINAD) of the two channels are almost the same and are noise dominated. The channel imbalance at this level remains the same as at 0 dBFS.
2. Frequency response
Let's see how the two available interpolation filters of the Sony act on the player’s frequency response in a high resolution analysis. The two following measurements have been made with a glide tone at -15 dBFS from the Denon Audio Technical CD:
The frequency response with the standard digital filter (cyan and yellow traces) is flat to about 0.15 dB in the audio band, whereas the optional digital filter rolls of the high frequencies earlier (red and green traces). Please note the perfect match in level between the two digital filters, until the higher roll-off rate of the optional filter kicks in around 14 kHz. None of the two filters significantly alters the interchannel phase.
Another way to look at the effect of the digital filters is to trace the wideband response with white noise up to ultrasonic frequencies (in this case 85 kHz):
The SCD-XA9000ES decodes emphasized tones at -20 dBFS from the Stereophile Test CD2 at almost correct levels:
Cross-checking with emphasized data at -10 dBFS from the HiFi-News and Record Review Test CD II (HFN 015) has demonstrated similarly correct results (not shown).
Crosstalk evaluated with spot tones from the Denon Audio Technical CD shows that there is a slight penalty to use the Tri-Power DAC mode, presumably because of the more complex signal path, but it is good in any case:
3. Noise and distortion measurements
Let's start with some Left/Right single point measurements about noise and distortion before proceeding with more graphs. All measurements are done with standard Audio Precision tests:
I apologize for the complexity of the table, but had many combinations to test and had to find a way to express the results.
The signal to noise ratio is consistent with the dynamic range. That indicates that the DACs does not mute their outputs when they are fed with a digital signal containing only zeros. The reason why the signal to noise ratio is greater than the dynamic range is because a digital signal containing only zeros does not exercise any quantization level above or below the 0 level, hence no quantization noise is generated at the output of the DAC.
The Tri-Power DAC mode consistently gives about 1.1 to 1.5 dB better signal to noise ratio compared to the front Left and Right channels of the 5.1 output, but the dynamic range and quantization noise are almost the same. The Tri-Power DAC mode is thus efficient on the analogue noise, but less so on the noise generated by the digital processing, which sets the limit of performance. Accordingly, the Tri-Power DAC mode must be more useful with stereo SACD replay than CD replay, because the very nature of DSD is to reject from the audio band the quantization noise that comes from the digital processing.
Paralleling the DACs and output stages seems to have no effects on intermodulation distortion, the largest discrepancies being with the 0 dBFS DIN IMD test and even in that case, the differences remain very low.
Likewise, choosing the optional digital filter does not make a significant difference with the various type of intermodulation signal, except with twin high frequencies of 19 and 20 kHz. So, in any case, the two digital filters implemented by Sony manage to keep things well in control in the audio band.
The resistance of the Sony SCD-XA9000ES to intersample overs is impressive. It is a behavior I had previously reported here. This is all the more interesting that the Pioneer DV-868AVi I have also reviewed showed no resistance to intersample overs whereas it uses Burr Brown PCM1738 DACs that are thought to be identical to the Sony CXD9657, as already stated. So either Sony managed to drive the DACs in a way to avoid clipping at the interpolation stage or the two chips are indeed not entirely identical and there are actually differences in the interpolation stage. At any rate, it may be be that here we get a champion of the league on the matter of intersample over.
To go further in the analysis, Audio Precision provides some standard tests to assess the noise performance of a CD player.
First test is to look at the FFT spectrum of an “Infinity Zero” signal from the Denon Audio Technical CD up to 80 kHz:
Please take into consideration than this measurement is free from any influence of the digital processing since the test signal contains only zeros. It only shows the analogue components of the noise. Here is the same test but from the front Lef and Right channels of the 5.1 output (that is, the no Tri-Power DAC mode):
The level of the noise floor and of the two small high frequency spurious tones are indeed slightly higher. By the way, the higher of the two spurious tone is at about 44 kHz: it may be related to the CD data clock.
A variation of this test suggested by Audio Precision is to restrict the measurement bandwidth to the low frequencies and to lower the sample rate in order to narrow the bin frequency width. That way, it is possible to search for mains frequency interference and power supply related noise with great resolution. First, with the Tri-Power DAC mode:
Second, at the front Left and Right channels of the 5.1 outputs, which show slightly higher noise floor and power supply spurious:
The other tests use the analogue analyzer to plot 1/3 octave curves of the noise with the same "Infinity Zero" signal. Although this method has less frequency resolution than the FFT analysis (the higher the frequency, the wider the noise bandwidth that each point of the curve represents contrary to an FFT analysis where each “bin” has equal bandwidth; that is why the curve obtained with the analogue analyzer regularly increases towards higher frequencies), it takes advantage of the greater dynamic range and the wider frequency response of the Audio Precision System One’s analogue analyzer over its ADCs.
The same test restricted to the audio bandwidth will be useful to compare to a special test that will be shown below:
Lastly, I add a test inspired by NTTY's practice to show an FFT spectrum up to 1 kHz when the player is reproducing a 1 kHz tone at 0 dBFS in search of power supply spurious noise. For this test, I set up an FFT at 8 ksps in order to improve bin frequency resolution to look after the output of the notch filter. Here I have to make a choice about which signal to use. I have chosen the 999.91 Hz sine with noise-shaped dither, which produces the lowest noise floor. All the spurious tones remain well under -130 dBr, thus benign:
THD+N vs frequency was assessed with spot tones at 0 dBFS without dither from the Pierre Vérany Digital Test CD. First within a 20 kHz bandwidth (i.e. the audio band):
There is no increase in distortion in the bass. With the standard digital filter (solid curves), the THD+N towards the high frequencies shows a tendency to go downward, a clue that the distortion pattern is constant with frequency as the upper harmonics move out of the analysis bandwidth. The sharp downward slope of the curve above 10 kHz is due to the fact that the second harmonic at 10 kHz and above falls outside the pass-band of the test, hence there is no longer any harmonic to measure, only noise. In fact, I had to expand a little the bottom of the vertical scale, because the curve of the right channels goes just under 0.001%. The upward curve from about 15 kHz most probably indicates an increase in the noise (including quantization noise) or distortion due to imaging above the 22.05 kHz Nyquist frequency of CD folding back into the audio band when the player has to reproduce high frequencies at high level. The optional digital filter (dashed curves) shows a sharp increase in THD+N above 13 kHz due to bleeding of imaging distortion in the audio band, an inescapable side effect of insufficient low-pass filtering above the Nyquist frequency, as is visible above with white noise. But at 0.05% (-66 dB) worst case at 20 kHz, the THD+N remains small nonetheless.
Second, here is the same test, but with a wider measurement bandwidth up to 80 kHz (standard digital filter only):
The increase of THD+N at higher frequencies is kept low by any measure, which is a very good result in my book.
The same measurement made with the optional digital filter shows a different picture:
The THD+N goes to the roof, mostly because the image of the test signal above the Nyquist frequency (22.05 kHz) is not suppressed by the digital filter. So better to use this digital filter when the frequency bandwidth of the musical signal is known to be within a 10 kHz or so bandwidth.
THD+N in function of levels has also been assessed (only with the standard digital filter) with the help the 999.91 Hz test signals from NTTY CD test disc. First with dithered tones (which gives a typical performance curve, because CD production is almost universally done with dither), and then with undithered tones (to see a truer picture of the level of performance of the player):
With dither, the curves remains almost flat up to 0 dBFS, which shows that the THD+N is dominated by the dither noise, not distortion. Without dither, the two curves stay at or below -98 dB THD+N up to -5 dBFS level or so. That means that the Sony SCD-XA9000ES is capable of 16 bits accuracy over almost a 65 dB wide dynamic range, and above -5 dBFS, little excess noise or distortion begin to appear.
Audio Precision provides a standard test to evaluate more qualitatively the SMPTE intermodulation distortion by looking at the digitization of the output of the analogue analyzer filter that removes the 60 Hz and 7 kHz tones to observe the actual distortion products:
The same test conducted with the optional digital filter shows an identical result (not shown).
The old 16 bits Burr Brown PCM78 ADCs of the Audio Precision System One probably limits the usefulness of FFTs of high level CCIF twin tone signals, because of the high dynamic of this signal relative to the noise floor. Here is an FFT of a -3.02 dBFS twin tones in a 23 kHz bandwidth:
Pairs of odd order distortion products (at 18 and 21 kHz, 17 and 22 kHz and 16 and 23 kHz) are visible, the highest pair being at about 90 dB under the level of each twin tones. The even order distortion at 1 kHz is some 105 dB under the level of each twin tones, which is very low.
The same test performed with the optional digital filter shows similarly good results, but, interrestingly, splitting of some intermodulation products and of the image of the 19 kHz tone at 23 kHz is noticeable:
Wideband analysis of this same CCIF test signal are also interresting:
The second graph shows that although very significant images of the twin tones are left above the Nyquist frequency, the suppression of the optional filter above 30 kHz is very good indeed.
For the same reason already explained about the dynamic range of the old Audio Precision ADCs, I do not think an FFT of the multitone signal from NTTY's test CD can give much detailed information. Moreover, the maximum FFT length that the System One is capable of restricts the bin frequency resolution in the bass. Anyway, here is the FFT spectrum of such signal, but from 100 Hz only:
4. Linearity Tests
With the kind help of NTTY, who has created a custom linearity test track with noise-shaped dithered spot tones down to -130 dBFS, I am able to assess the player's DAC deviation from linearity with the System One's software-implemented selective voltmeter:
I have used the same scale than the one Amirm uses for its own tests to ease comparison. The yellow curve (right channel) stops at -100 dBFS because the right channel of the Audio Precision was unable to settle to any reading under that level. The player's output deviates significantly from linearity somewhere between -110 dBFS and -120 dBFS, where the error is at +0.6 dB. This is roughly 18.5 bits of accuracy.
I made an FFT analysis of the -130 dBFS sine signals which shows better results at this very low level, presumably thanks to the effects of the averaging, which is not a component of the above linearity test:
That means that the players tends towards the correct level even at that low a level when the signal is sustained long enough to be observed.
(To be continued in message #2)
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... when it still can read them! 
