Hello everyone,
This is a review and measurements of the Sony CDP-597 CD player:
Sony CDP-597 - Presentation
This one was released in 1992, and was a middle-entry level offer from Sony, that means a reasonably priced CD Player.
It was kindly sent to me by a forum member, thanks to him. It arrived damaged, unfortunately, someone tried to play soccer with it. The face plate was damaged in the process, bended forward. I was able to fix most of it, as you can see from the picture above. Everything else survived the bad treatment, especially the super fast drive KSS-240A.
The back side is representative of the selling price of the time:
We get only RCA analog outputs, in fixed and variable mode, that's it.
The specs were the below (taken from the service guide):
Err, no, no optional Audio Optical connecting cord, you forgot to add a hole at the back of it , Sony 
(EDIT: US model had a digital output, so I was wrong, thanks @Scytales)
Let's have a look at the inside:
Well, ok, low end I'd say. But it's a Sony, so everything makes sense. Measurements will tell us more.
----
EDIT: after feedback from both @bargainguy and @Scytales, thanks to them.
The web tells us the Oversampling is the CXD2560M and the DAC is the CXD2561AM, both lacking a datasheet, Sony kept these for them. However, the service guide shows the below block diagram, respectively:
It is clear that the output of the CXD2560M is the input of the CXD2561. But, to be honest, I fail to decipher the left one, which supposed to be the oversampling digital filter. But for the right one, the DAC, I understand the below:
This is a closer view of the board showing that the two respective ICs are below the board (IC302 and IC303):
END EDIT
----
The below is good news, and that is the super fast KSS-240:
It's not the best at tracking (measurements will also confirm) but gosh it's so fast that you can only get addicted to it.
This Sony is of course very pleasant to use with that mega fast KSS, and especially for me, with my 40 tracks test CD, most of them having multiple test tones in one track, and I often need to fast forward to a precise location. This KSS-240A is the ultimate companion for that.
Listening to this player was an equal pleasure, like so many others. I must admit that I listened to it after completing all measurements. And what I saw made me think I would only have pleasure. And so yes, it was a very agreeable experience to listen to this CD Player. Is it a bias? Yes it is, based on tangible results.
Time has come to share with you why I had satisfaction with this unknown player.
Sony CDP-597 - Measurements (RCA outputs)
All measurements performed with an E1DA Cosmos ADCiso (grade O), and the Cosmos Scaler (100kohms from unbalanced input) for analog outputs, and a Motu UltraLite Mk5 for digital.
I am now consistent with my specific measurements for CD Players, as I described them in the post “More than we hear”, and as I reported them for the Onkyo C-733 review. Over time, this will help comparing the devices I reviewed.
The Sony outputs a low 1.75Vrms, that is 1.1dB less than the standard 2Vrms. It means when directly compared to another player, it might not shine unless you increase the gain by the same 1.1dB with your preamplifier.
The tow channels match at 0.12dB, which is good for the class. The unbalanced outputs respect absolute polarity. Phase is dead flat.
----
As usual, let's start with my standard 999.91Hz sine @0dBFS (without dither) from the Test CD (RCA out):
The two channels are shown, and only one get evaluated, but they are similarlyl. ENOB is limited by the distortion and this level.
Let's have a look at -6dBFS as I'm used to show:
Distortion went down by nearly 10dB! The DAC does not like to handle very high level tones. Note the side bands around the fundamental, they are due to an interaction with the power supply. That said, at -110dBr, they will remain hidden into music.
----
I guess you saw limited power supply leakage:
We get only a noticeable 100hz (Europe, mains at 50Hz) and at -125dBr, and we can ignore it. This player has a very silent power supply, well done Sony.
But again, note the side bands around the fundamental (900Hz and 800Hz), due to an interaction with the PS. They are close to the fundamental and they will remain easily hidden into music, but they are here. I still think these are crazy good results for the time and considering the age of this non-serviced player (33 years old...).
----
Next is the bandwidth:
This is very flat (-0.1dB only) and no ringing can be seen. This was top class for the time. We can see the deviation between the two channels (0.12dB) which is more than acceptable.
Let's have a look at the oversampling filter of this CD player:
Well... nice! We get 80dB+ of attenuation, with very reasonable increase of noise floor due to the noise shaper. The filter has no issue to cancel aliases of the 18kHz and 20kHz test tones, this is very good! It is fully active at 24kHz, and that's ok to me. This was much better than what Philips had to offer at the time.
----
Let's have a look at the multitone test that a lot of you like very much:
This CD player is free of distortion much beyond 16its with that punishing test. I'm impressed (especially given the price and the class).
----
Let's move on to the jitter test:
Nailed! Red trace is the analysis from the WAV file, and the blue one is from the CDP-597 (RCA outs). Besides the side bands that I already mentioned, this is perfect!
Note the higher noise floor due to the noise shaper of the converter, and compared to a classical R2R conversion (without noise shaper), like the one from the Denon DCD-655.
----
Started with the Teac VRDS-20 review, and on your request + support to get it done (more here), I'm adding now an "intersample-overs" test which intends to identify the behavior of the digital filtering and DAC when it come to process near clipping signals. Because of the oversampling, there might be interpolated data that go above 0dBFS and would saturate (clip) the DAC and therefore the output. And this effect shows through distorsion (THD+N measurement up to 96kHz):
I kept some references and will keep the same for other reviews, so you can quickly compare. The results of the Sony mean that it has no headroom in its interpolator, which is not a surprise, unfortunately. Note that is was the same with the 8 times more expensive Sony CDP-X333ES of the same time...
----
Let's continue with the good old 3DC measurement that Stereophile was often using as a proof of low noise DAC. It is from an undithered 997Hz sine at -90.31dBFS. With 16bits, the signal should appear (on a scope) as the 3DC levels of the smallest symmetrical sign magnitude digital signal:
We can very easily recognize the 3DC levels, which should show as a square (with Gibbs Phenomenon, due to the limited band). The symmetry is good. The operating noise of this player is very low and the linearity is very good (thanks to the 1bit conversion). This was best in class at the time, for a delta-sigma conversion. I wonder if Sony was into anything else but perfection?
----
Other measurements (not shown):
The above are not best in class, but more than good enough.
----
Last and not least, I like to run a THD vs Frequency sweep at -12dBFS as it shows how the conversion has evolved over time. I am currently using the beta version of REW and I discovered that this sweep gives better and more reliable results than before. I overlaid the result with the Marantz CD-80 (and its crowned Philips TDA1541A DAC) of the same time, much more expensive, and the Sony CDP-X333ES that I already mentioned:
These are again crazy good results for a CD player worth not much and nothing today. You get a winner here!
Very Special Test - Max DAC resolution of a CD Player
I can't test the digital output of this player since it does not have one, too bad.
So, I take this opportunity to introduce you to a "ultimate" resolution test that I've been thinking about for months, but never got to the point I could standardize it. And after a couple of more days thinking and experimenting about it, now I can!
Sorry, I don't know how to make the long story short, but I'll do my best.
You know that PCM audio 16bits/44.1kHz has limited resolution set by 65536 integer values "only". All goes well when the signal is a high level one (say max 0dBFS), but "quantization errors" increase as the level goes down due to limited integer values. Better to illustrate that:
Left is a non-dithered 999.91Hz sine @0dBFS (the digital max) and right is the same but at -50dBFS (big attenuation). You can appreciate the mess only due to quantization (rounding) errors which generate non-harmonic distortion. This has a solution, it's called dither:
If the left trace is nearly the same, the right one massively improved! The dither noise (low random noise) helped reducing the quantization noise... at the expense of losing half a bit of resolution. Indeed, this low noise needs space on its own in the 16bits data. I used rectangular dither of Audacity to create these WAV files. It's a good one and consumes only 0.5LSB (half a bit), so we are limited to 15.5bits max resolution with that.
Can we do better? Yes, we can!
This is when shape dither enters the arena. With that "shaped" noise introduced to create the test files (or any 16bits master), it is possible to locally lower the noise, in the audio band. Let's have a look:
As you can see, this Software intervention lowers the noise floor (a lot) from 20Hz to 6kHz, that is where it counts for our ears. If I process the resulting ENOB resolution with a narrower than usual bandwidth (20Hz to 6kHz), I get a practical max of 18.7bits (from the WAV files).
As I needed to verify my data and create a test protocol, I checked the above with several CD players, and so far two of them achieved the above maximum (SMSL PL200 and OPPO BDP-95).
Last and certainly not least, it was important for me to set at what level this test should be done. After months of countless tests, I decided to go for a test tone @-12dBFS. I’ve been using this level since the beginning for my THD vs Frequency sweep, because for what I like to review (old devices and new ones), that it is the level best revealing differences between players and DACs.
So, this little Sony, worth not much at the time, how does it compete? Quite well actually:
The above translate into 17.5bits of resolution. In other words, it means 93.58% of the possible maximum, and that's a very good score. I will now include this measurement into my reviews, unless you express objections to it, as per the below:
----
As I did with the Sony CDP-597, I add a "max DAC resolution" measurement test. It is performed from a 999.91Hz sine @-12dBFS with shape dither (from Audacity). I restrict the THD+N span to 20Hz - 6kHz in REW not to account for the noise of the shape dither beyond 6kHz. I take the calculated ENOB and simply add 2bits to it (due to the -12dB attenuation, as 1bits=6dB). The potential maximum, when calculated from the digital WAV file, is 18.7bits under this test. A "transparent" DAC should achieve 18.7bits, ie 100% in this test.
Here are the results compared to others:
Sony CDP-597 - Testing the drive
What would be good measurements if the drive would not properly read a slightly scratched CD, or one that was created at the limits of the norm? The below tests reply to these questions.
The Sony took 4 seconds to read the TOC of my 40 tracks test CD (this is good).
The Sony was able to read without generating typical interpolation digital noise with dropouts up to 1mm. Beyond that, not only "digital clicks" could be heard but it dropped few seconds of music.
This is similar to what I measured with other KSS-240A heads.
Conclusion
What a surprise! This CD player is worth nothing (today) but gives you a lot more than so many others!
I must say bravo to Sony. Thirty Three years later, this "basic" CD player still delivers and would make so many "high-end" players jealous!
If you find one, I tell you, just take time to enjoy how it sounds. And only think about finding the best CD masters you can, because this one player will not prevent them from shining,
I hope you enjoy the review, and as always, (positive) criticisms, questions and need for more info are more than welcome!
Cheers.
This is a review and measurements of the Sony CDP-597 CD player:
Sony CDP-597 - Presentation
This one was released in 1992, and was a middle-entry level offer from Sony, that means a reasonably priced CD Player.
It was kindly sent to me by a forum member, thanks to him. It arrived damaged, unfortunately, someone tried to play soccer with it. The face plate was damaged in the process, bended forward. I was able to fix most of it, as you can see from the picture above. Everything else survived the bad treatment, especially the super fast drive KSS-240A.
The back side is representative of the selling price of the time:
We get only RCA analog outputs, in fixed and variable mode, that's it.
The specs were the below (taken from the service guide):
(EDIT: US model had a digital output, so I was wrong, thanks @Scytales)Let's have a look at the inside:
Well, ok, low end I'd say. But it's a Sony, so everything makes sense. Measurements will tell us more.
----
EDIT: after feedback from both @bargainguy and @Scytales, thanks to them.
The web tells us the Oversampling is the CXD2560M and the DAC is the CXD2561AM, both lacking a datasheet, Sony kept these for them. However, the service guide shows the below block diagram, respectively:
It is clear that the output of the CXD2560M is the input of the CXD2561. But, to be honest, I fail to decipher the left one, which supposed to be the oversampling digital filter. But for the right one, the DAC, I understand the below:
- S/P: Serial to parallel conversion of the PCM signal
- LINEAR INTERPOLATION: Oversampling to higher sampling rate to accommodate for the noise shaper of the 1bit conversion
- CUBIC NS: Noise Shaper of the 3rd order
- NON-SYMETRICAL PWM: conversion of the 1bit data stream to analog
This is a closer view of the board showing that the two respective ICs are below the board (IC302 and IC303):
END EDIT
----
The below is good news, and that is the super fast KSS-240:
It's not the best at tracking (measurements will also confirm) but gosh it's so fast that you can only get addicted to it.
This Sony is of course very pleasant to use with that mega fast KSS, and especially for me, with my 40 tracks test CD, most of them having multiple test tones in one track, and I often need to fast forward to a precise location. This KSS-240A is the ultimate companion for that.
Listening to this player was an equal pleasure, like so many others. I must admit that I listened to it after completing all measurements. And what I saw made me think I would only have pleasure. And so yes, it was a very agreeable experience to listen to this CD Player. Is it a bias? Yes it is, based on tangible results.
Time has come to share with you why I had satisfaction with this unknown player.
Sony CDP-597 - Measurements (RCA outputs)
All measurements performed with an E1DA Cosmos ADCiso (grade O), and the Cosmos Scaler (100kohms from unbalanced input) for analog outputs, and a Motu UltraLite Mk5 for digital.
I am now consistent with my specific measurements for CD Players, as I described them in the post “More than we hear”, and as I reported them for the Onkyo C-733 review. Over time, this will help comparing the devices I reviewed.
The Sony outputs a low 1.75Vrms, that is 1.1dB less than the standard 2Vrms. It means when directly compared to another player, it might not shine unless you increase the gain by the same 1.1dB with your preamplifier.
The tow channels match at 0.12dB, which is good for the class. The unbalanced outputs respect absolute polarity. Phase is dead flat.
----
As usual, let's start with my standard 999.91Hz sine @0dBFS (without dither) from the Test CD (RCA out):
The two channels are shown, and only one get evaluated, but they are similarlyl. ENOB is limited by the distortion and this level.
Let's have a look at -6dBFS as I'm used to show:
Distortion went down by nearly 10dB! The DAC does not like to handle very high level tones. Note the side bands around the fundamental, they are due to an interaction with the power supply. That said, at -110dBr, they will remain hidden into music.
----
I guess you saw limited power supply leakage:
We get only a noticeable 100hz (Europe, mains at 50Hz) and at -125dBr, and we can ignore it. This player has a very silent power supply, well done Sony.
But again, note the side bands around the fundamental (900Hz and 800Hz), due to an interaction with the PS. They are close to the fundamental and they will remain easily hidden into music, but they are here. I still think these are crazy good results for the time and considering the age of this non-serviced player (33 years old...).
----
Next is the bandwidth:
This is very flat (-0.1dB only) and no ringing can be seen. This was top class for the time. We can see the deviation between the two channels (0.12dB) which is more than acceptable.
Let's have a look at the oversampling filter of this CD player:
Well... nice! We get 80dB+ of attenuation, with very reasonable increase of noise floor due to the noise shaper. The filter has no issue to cancel aliases of the 18kHz and 20kHz test tones, this is very good! It is fully active at 24kHz, and that's ok to me. This was much better than what Philips had to offer at the time.
----
Let's have a look at the multitone test that a lot of you like very much:
This CD player is free of distortion much beyond 16its with that punishing test. I'm impressed (especially given the price and the class).
----
Let's move on to the jitter test:
Nailed! Red trace is the analysis from the WAV file, and the blue one is from the CDP-597 (RCA outs). Besides the side bands that I already mentioned, this is perfect!
Note the higher noise floor due to the noise shaper of the converter, and compared to a classical R2R conversion (without noise shaper), like the one from the Denon DCD-655.
----
Started with the Teac VRDS-20 review, and on your request + support to get it done (more here), I'm adding now an "intersample-overs" test which intends to identify the behavior of the digital filtering and DAC when it come to process near clipping signals. Because of the oversampling, there might be interpolated data that go above 0dBFS and would saturate (clip) the DAC and therefore the output. And this effect shows through distorsion (THD+N measurement up to 96kHz):
| Intersample-overs tests Bandwidth of the THD+N measurements is 20Hz - 96kHz | 5512.5 Hz sine, Peak = +0.69dBFS | 7350 Hz sine, Peak = +1.25dBFS | 11025 Hz sine, Peak = +3.0dBFS |
| Teac VRDS-20 | -30.7dB | -26.6dB | -17.6dB |
| Yamaha CD-1 | -84.6dB | -84.9dB | -78.1dB |
| Denon DCD-900NE | -34.2dB | -27.1dB | -19.1dB |
| Denon DCD-SA1 | -33.6dB | -27.6dB | -18.3dB |
| Onkyo C-733 | -88.3dB | -40.4dB | -21.2dB |
| Denon DCD-3560 | -30.2dB | -24.7dB | -17.4dB |
| Myryad Z210 | -70.6dB (noise dominated) | -71.1dB (noise dominated) | -29.4dB (H3 dominated) |
| Sony CDP-X333ES | -30.5dB | -24.8dB | -16.3dB |
| BARCO-EMT 982 | -32.7dB | -24.5dB | -16.3dB |
| TASCAM CD-200 | -73.5dB | -36.3dB | -19.7dB |
| Sony CDP-597 | -30.4dB | -24.7dB | -16.5dB |
I kept some references and will keep the same for other reviews, so you can quickly compare. The results of the Sony mean that it has no headroom in its interpolator, which is not a surprise, unfortunately. Note that is was the same with the 8 times more expensive Sony CDP-X333ES of the same time...
----
Let's continue with the good old 3DC measurement that Stereophile was often using as a proof of low noise DAC. It is from an undithered 997Hz sine at -90.31dBFS. With 16bits, the signal should appear (on a scope) as the 3DC levels of the smallest symmetrical sign magnitude digital signal:
We can very easily recognize the 3DC levels, which should show as a square (with Gibbs Phenomenon, due to the limited band). The symmetry is good. The operating noise of this player is very low and the linearity is very good (thanks to the 1bit conversion). This was best in class at the time, for a delta-sigma conversion. I wonder if Sony was into anything else but perfection?
----
Other measurements (not shown):
- IMD AES-17 DFD "Analog" (18kHz & 20kHz 1:1) : -87.1dB
- IMD AES-17 DFD "Digital" (17'987Hz & 19'997Hz 1:1) : -78.4dB
- IMD AES-17 MD (41Hz & 7993Hz 4:1): -81dB
- IMD CCIF (19kHz & 20kHz 1:1) : -78dB
- IMD DIN (250Hz & 8kHz 4:1) : -77dB
- IMD SMPTE (60Hz & 7kHz 1:4) : -78.5B
- IMD TDFD Bass (41Hz & 89Hz 1:1) : -101.5dB
- IMD TDFD (13'58Hz & 19841Hz 1:1) : -98.6dB
- Dynamic Range : 97.6dB (without dither @-60dBFS)
- Crosstalk: -111dBr (100Hz), -96dBr (1khz), -78dBr (10kHz)
- Pitch Error : 19'996.34Hz (19'997Hz requested) ie 33ppm
- Gapless playback : Yes
The above are not best in class, but more than good enough.
----
Last and not least, I like to run a THD vs Frequency sweep at -12dBFS as it shows how the conversion has evolved over time. I am currently using the beta version of REW and I discovered that this sweep gives better and more reliable results than before. I overlaid the result with the Marantz CD-80 (and its crowned Philips TDA1541A DAC) of the same time, much more expensive, and the Sony CDP-X333ES that I already mentioned:
These are again crazy good results for a CD player worth not much and nothing today. You get a winner here!
Very Special Test - Max DAC resolution of a CD Player
I can't test the digital output of this player since it does not have one, too bad.
So, I take this opportunity to introduce you to a "ultimate" resolution test that I've been thinking about for months, but never got to the point I could standardize it. And after a couple of more days thinking and experimenting about it, now I can!
Sorry, I don't know how to make the long story short, but I'll do my best.
You know that PCM audio 16bits/44.1kHz has limited resolution set by 65536 integer values "only". All goes well when the signal is a high level one (say max 0dBFS), but "quantization errors" increase as the level goes down due to limited integer values. Better to illustrate that:
Left is a non-dithered 999.91Hz sine @0dBFS (the digital max) and right is the same but at -50dBFS (big attenuation). You can appreciate the mess only due to quantization (rounding) errors which generate non-harmonic distortion. This has a solution, it's called dither:
If the left trace is nearly the same, the right one massively improved! The dither noise (low random noise) helped reducing the quantization noise... at the expense of losing half a bit of resolution. Indeed, this low noise needs space on its own in the 16bits data. I used rectangular dither of Audacity to create these WAV files. It's a good one and consumes only 0.5LSB (half a bit), so we are limited to 15.5bits max resolution with that.
Can we do better? Yes, we can!
This is when shape dither enters the arena. With that "shaped" noise introduced to create the test files (or any 16bits master), it is possible to locally lower the noise, in the audio band. Let's have a look:
As you can see, this Software intervention lowers the noise floor (a lot) from 20Hz to 6kHz, that is where it counts for our ears. If I process the resulting ENOB resolution with a narrower than usual bandwidth (20Hz to 6kHz), I get a practical max of 18.7bits (from the WAV files).
As I needed to verify my data and create a test protocol, I checked the above with several CD players, and so far two of them achieved the above maximum (SMSL PL200 and OPPO BDP-95).
Last and certainly not least, it was important for me to set at what level this test should be done. After months of countless tests, I decided to go for a test tone @-12dBFS. I’ve been using this level since the beginning for my THD vs Frequency sweep, because for what I like to review (old devices and new ones), that it is the level best revealing differences between players and DACs.
So, this little Sony, worth not much at the time, how does it compete? Quite well actually:
The above translate into 17.5bits of resolution. In other words, it means 93.58% of the possible maximum, and that's a very good score. I will now include this measurement into my reviews, unless you express objections to it, as per the below:
----
As I did with the Sony CDP-597, I add a "max DAC resolution" measurement test. It is performed from a 999.91Hz sine @-12dBFS with shape dither (from Audacity). I restrict the THD+N span to 20Hz - 6kHz in REW not to account for the noise of the shape dither beyond 6kHz. I take the calculated ENOB and simply add 2bits to it (due to the -12dB attenuation, as 1bits=6dB). The potential maximum, when calculated from the digital WAV file, is 18.7bits under this test. A "transparent" DAC should achieve 18.7bits, ie 100% in this test.
Here are the results compared to others:
| CD Player model or DAC | Calculated ENOB (999.91Hz sine @-12dBFS with shape dither, THD+N span = 20Hz - 6kHz) | Percentage of max resolution achieved (higher is better) |
| OPPO BDP-95 | 18.7bits | 100% |
| SMSL PL-200 | 18.7bits | 100% |
| SMSL PS-200 (from CD player) | 18.6bits | 99.47% |
| Denon DCD-SA1 | 18.5bits | 98.93% |
| Denon DCD-900NE | 18.5bits | 98.93% |
| Onkyo C-733 | 18bits | 96.26% |
| SMSL PL150 | 18bits | 96.26% |
| SMSL PL100 | 17.9bits | 95.72% |
| Sony CDP-597 | 17.5bits | 93.58% |
| Onkyo DX-7355 | 17.3bits | 92.51% |
| Denon DCD-3560 | 17.2bits | 91.98% |
| Yamaha CD-S303 | 16.8bits | 89.84% |
| Accuphase DP-70 | 16.6bits | 88.77% |
| Sony CDP-337ESD | 16.6bits | 88.77% |
| Teac VRDS-25x | 16.5bits | 88.24% |
| Marantz CD-73 | 14.9bits | 79.68% |
Sony CDP-597 - Testing the drive
What would be good measurements if the drive would not properly read a slightly scratched CD, or one that was created at the limits of the norm? The below tests reply to these questions.
The Sony took 4 seconds to read the TOC of my 40 tracks test CD (this is good).
| Test type | Technical test | Results |
| Variation of linear cutting velocity | From 1.20m/s to 1.40m/s | Pass |
| Variation of track pitch | From 1.5µm to 1.7µm | Pass |
| Combined variations of track pitch and velocity | From 1.20m/s & 1.5µm to 1.40m/s & 1.7µm | Pass |
| HF detection (asymmetry pitch/flat ratio) | Variation from 2% to 18% | Pass |
| Dropouts resistance | From 0.05mm (0.038ms) to 4mm (3.080ms) | up to 1mm |
| Combined dropouts and smallest pitch | From 1.5µm & 1mm to 1.5µm & 2.4mm | up to 1mm |
| Successive dropouts | From 2x0.1mm to 2x3mm | up to 1mm |
The Sony was able to read without generating typical interpolation digital noise with dropouts up to 1mm. Beyond that, not only "digital clicks" could be heard but it dropped few seconds of music.
This is similar to what I measured with other KSS-240A heads.
Conclusion
What a surprise! This CD player is worth nothing (today) but gives you a lot more than so many others!
I must say bravo to Sony. Thirty Three years later, this "basic" CD player still delivers and would make so many "high-end" players jealous!
If you find one, I tell you, just take time to enjoy how it sounds. And only think about finding the best CD masters you can, because this one player will not prevent them from shining,
I hope you enjoy the review, and as always, (positive) criticisms, questions and need for more info are more than welcome!
Cheers.
Last edited:
