Hello Everyone,
This is a review and detailed measurements of the NAD C540 CD Player and Transport.
It was loaned to me by a friend who read the review of the Azur 640C V2, and saw the desire of @trevor_bartram to get the same review from a NAD C540. And since he had that one, he suggested me to go for it. So here we are.
NAD C540 - Presentation
Released in 1999, this more than a quarter century old CD player uses the BurrBrown PCM1716, a 24bits DAC that includes an 8x oversampling filter (selectable between slow or fast). As per the datasheet, it ranges from -90 to 97 of THD+N @0dBFS, we'll check that.
As per my research, it was a not so expensive CD Player at the time (around 220$). The specs were (taken from the Service Manual):
I like the good set of specs, especially fact it is mentioned it applies de-emphasis, including the error (I'll check too, of course). There's also a mention of real linearity, said to be better than -80dB, and I can tell you it's much better than that, hopefully for a delta-sigma DAC.
On the back, we get the minimum and essential:
RCA for analog output and SPDIF via RCA too, no Toslink.
Let's have a look at the inside:
The drive is a Sanyo that has been replaced in this one. The blue board hosts all functions, from SERVO control to analog outputs.
User experience
The drive is pleasantly fast, especially to FFW/REW, and also to skip one or several tracks, I like it. Some of the buttons are not so reactive and I suppose this an aging effect.
I'm always missing a headphones out, but for an entry level unit, I guess it's ok.
It is gapless playback, proper CD player that is, together with de-emphasis correctly applied.
NAD C540 - Measurements (Analog outputs)
All measurements performed with an E1DA Cosmos ADCiso (grade 0), 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 SMSL PL-200 review. I used the commercial version of my Audio Technical CD for all measurements. Over time, this will help comparing the devices I reviewed.
The NAD C540 outputs a higher than usual 2.262Vrms from left channel, and 2.241V from right channel (0.08dB less). This is a good 1.1dBu more than from the standard 2Vrms, which is enough to make this one "sound better" than most of the competitors, because it plays louder...
Phase is dead flat, and unbalanced outputs invert polarity.
----
As usual, let's start with my standard 999.91Hz sine @0dBFS (without dither) from the Test CD (RCA out):
The NAD is shy of almost one bit when compared to the best in class CD Players. This is due to the noise floor and some unwanted and non-harmonic distortion. That said, it is more than good enough and will remain hidden into music. And note that we are in the range of BurrBrown published specs. That means we can say thanks to NAD not to have degraded BurrBrown's engineering.
Let's try the same at -6dBFS:
Noise and distortion have both improved, so the conversion of this NAD runs cooler with tones a bit further from full scale.
----
Let's have a look a potential Power Supply leakages, the below is a 20Hz to 1kHz zoom with a punishing 512k FFT length to reveal issues:
Superb trace, absolutely no PS related disruption. But there is a weird spike at 328Hz. I don't know the cause (wobble generator?) as I never saw that before.
----
Next is the bandwidth:
This is within specs and very flat, only -0.3dB at 20kHz. You can see the 0.08dB channel imbalance, which is very low (and so very good).
----
Let's have a look at the behavior of the oversampling filter beyond 20kHz:
This view shows that NAD went for the fast filter of the BurrBrown DAC (I like that) and that the attenuation is max -80dB. That is a little weak, but again per specs of the DAC.
The aliases of the AES double tones (18kHz & 20kHz) are decently attenuated beyond the audio band.
This view also reveals how the delta-sigma modulator rejects noise beyond the audio band, as you can see the noise floor slowly increasing beyond 25kHz. This means, again, that this is kind of "value oriented" choice, more than high-end (less processing power required).
----
Let's have a look at the multitone test that a lot of you like very much:
This is a little more disrupted than best in class, especially at high frequencies were we get more than usual distortion (around 10dB more than best in class). This is not an audible concern though but it could have been better.
Note that the last 20kHz tone is missing on the graph because of the higher than usual pitch error (145ppm) which makes go a bit beyond 20kHz.
----
Oh yes, the jitter test:
Again, not best in class, but much more than good enough, to be honest. The two mains side bands are not only close to the fundamental, but low in level (-107dBr) and so will remain hidden to your ears.
----
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):
The NAD has no headroom for intersample overs. Too bad as so many CD Masters are recorded too hot.
----
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:
There is a good symmetry meaning that the published specs were indeed pessimist. There is a little more noise than best in class, but we can very clearly see the 3 fundamental levels of the 16bits PCM code converted, so this is very good since many older R2R converters were only dreaming of that performance...
----
Other measurements (not shown):
The Dynamic range is shy of 2dB compared to best in class, and of course still very good.
Crosstalk is extremely low, in the best in class category.
Pitch error is a high 145ppm+ which is unusual. The x'tal in use is said to be of a 30ppm precision per the service guide. So, I'd suspect that the coupling capacitors (20pF) have aged and would need a refresh, maybe.
----
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 overlayed the results with the Azur 640C V2:
The NAD is let down by the H2 distorsion it generates at this lower level. Not much of a concern though, at -92dB, especially being easily hidden second harmonic, but we are used to best in class results here.
----
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:
Again, the NAD is let down by the high H2 that it generates and it's the only reason. As a consequence, the above results look worse than they are in real life, but hey, that's all about this test.
Of course, harmonic distorsion that is H2 driven is the one we should be less concerned about. And to be transparent, let me add this measurement for once:
As you can see, besides the H2, there's not much to mention. Had the H2 been on par with the H4, this would qualify as best in class.
----
On demand from the community, I now add a "de-emphasis test" to verify that this flag is detected and the compliance with the expected de-emphasis curve.
When the curve is within specs, we should see 8dB less at 11kHz, which is exactly what we get with the NAD (better than specs).
NAD C540 - 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.
Here are the results:
I could see the interpolation mechanism kicking off as soon as with a 0.5mm gap, but I could not hear it. No "clicks" until 1.5mm and the drive did not stop reading even with 4mm dropouts (although it was skipping few seconds).
The above are decent results and if you have CDs in good condition, this is more than good enough.
NAD C540 - Digital output
Ok, so we get a decent CD player here, especially for the price. And to expect better from a modern DAC, we need a perfect digital output. Let's test that.
This is my standard 999.91Hz @0dBFS (no dither):
This is the same as the original WAV file that was used to create the CD track.
The 3DC test is nailed too, of course:
My ultimate proof of "perfect" digital output is when I reuse the intersample overs test at 5512.50Hz, with a phase shift of 67.5°, like I did for the TASCAM CD-200 review. This signal generates an overshoot of +0.69dB. And so, if the signal would be modified before being sent (by an ASRC for instance), it would show either a reduction of amplitude or we'd see some sort of saturation/increase of noise/distorsion. So here we go with the NAD via the Coax out:
No distortion and the dashboard shows +0.69dBFS as expected. No ASRC on the digital path here. SNR is only 95.5dB because there is rectangle dither in this test file (consuming half a bit of resolution).
So we get a "perfect" transport in case you're not happy with the internal DAC.
Conclusion
Besides a little higher than usual H2 at low level and high frequencies, I shall be happy with what I measured, considering this was a budget CD Player in 1999.
I liked the speed of the drive, fact that the digital output is "perfect", and I must say that the internal DAC will remain transparent to your ears even if not perfect. For the price, I thing there's not much more to desire.
Reliability, yeah, a familiar weak spot with NAD gear... The drive of this one had to be swapped out, but it’s running again, for the next quarter century, if we’re lucky
I hope you enjoyed this review and I wish you a nice "JeuDredi" as we say in the French part of Switzerland as we feel the weekend coming (combination of Jeudi (Thursday) and Vendredi (Friday), could be ThurFriday in English, I suppose).
Cheers.
Flo
This is a review and detailed measurements of the NAD C540 CD Player and Transport.
It was loaned to me by a friend who read the review of the Azur 640C V2, and saw the desire of @trevor_bartram to get the same review from a NAD C540. And since he had that one, he suggested me to go for it. So here we are.
NAD C540 - Presentation
Released in 1999, this more than a quarter century old CD player uses the BurrBrown PCM1716, a 24bits DAC that includes an 8x oversampling filter (selectable between slow or fast). As per the datasheet, it ranges from -90 to 97 of THD+N @0dBFS, we'll check that.
As per my research, it was a not so expensive CD Player at the time (around 220$). The specs were (taken from the Service Manual):
I like the good set of specs, especially fact it is mentioned it applies de-emphasis, including the error (I'll check too, of course). There's also a mention of real linearity, said to be better than -80dB, and I can tell you it's much better than that, hopefully for a delta-sigma DAC.
On the back, we get the minimum and essential:
RCA for analog output and SPDIF via RCA too, no Toslink.
Let's have a look at the inside:
The drive is a Sanyo that has been replaced in this one. The blue board hosts all functions, from SERVO control to analog outputs.
User experience
The drive is pleasantly fast, especially to FFW/REW, and also to skip one or several tracks, I like it. Some of the buttons are not so reactive and I suppose this an aging effect.
I'm always missing a headphones out, but for an entry level unit, I guess it's ok.
It is gapless playback, proper CD player that is, together with de-emphasis correctly applied.
NAD C540 - Measurements (Analog outputs)
All measurements performed with an E1DA Cosmos ADCiso (grade 0), 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 SMSL PL-200 review. I used the commercial version of my Audio Technical CD for all measurements. Over time, this will help comparing the devices I reviewed.
The NAD C540 outputs a higher than usual 2.262Vrms from left channel, and 2.241V from right channel (0.08dB less). This is a good 1.1dBu more than from the standard 2Vrms, which is enough to make this one "sound better" than most of the competitors, because it plays louder...
Phase is dead flat, and unbalanced outputs invert polarity.
----
As usual, let's start with my standard 999.91Hz sine @0dBFS (without dither) from the Test CD (RCA out):
The NAD is shy of almost one bit when compared to the best in class CD Players. This is due to the noise floor and some unwanted and non-harmonic distortion. That said, it is more than good enough and will remain hidden into music. And note that we are in the range of BurrBrown published specs. That means we can say thanks to NAD not to have degraded BurrBrown's engineering.
Let's try the same at -6dBFS:
Noise and distortion have both improved, so the conversion of this NAD runs cooler with tones a bit further from full scale.
----
Let's have a look a potential Power Supply leakages, the below is a 20Hz to 1kHz zoom with a punishing 512k FFT length to reveal issues:
Superb trace, absolutely no PS related disruption. But there is a weird spike at 328Hz. I don't know the cause (wobble generator?) as I never saw that before.
----
Next is the bandwidth:
This is within specs and very flat, only -0.3dB at 20kHz. You can see the 0.08dB channel imbalance, which is very low (and so very good).
----
Let's have a look at the behavior of the oversampling filter beyond 20kHz:
This view shows that NAD went for the fast filter of the BurrBrown DAC (I like that) and that the attenuation is max -80dB. That is a little weak, but again per specs of the DAC.
The aliases of the AES double tones (18kHz & 20kHz) are decently attenuated beyond the audio band.
This view also reveals how the delta-sigma modulator rejects noise beyond the audio band, as you can see the noise floor slowly increasing beyond 25kHz. This means, again, that this is kind of "value oriented" choice, more than high-end (less processing power required).
----
Let's have a look at the multitone test that a lot of you like very much:
This is a little more disrupted than best in class, especially at high frequencies were we get more than usual distortion (around 10dB more than best in class). This is not an audible concern though but it could have been better.
Note that the last 20kHz tone is missing on the graph because of the higher than usual pitch error (145ppm) which makes go a bit beyond 20kHz.
----
Oh yes, the jitter test:
Again, not best in class, but much more than good enough, to be honest. The two mains side bands are not only close to the fundamental, but low in level (-107dBr) and so will remain hidden to your ears.
----
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 |
| SMSL PL100 | -53.1dB | -31dB | -19.1dB |
| OPPO BDP-95 | -39dB | -28.8dB | -19.2dB |
| OPPO BDP-95 (vol -2dB) | -95dB | -97.5dB | -32.7dB |
| SMSL PL200 | -94.8dB | -97dB | -39.5dB |
| SMSL PL200 (vol -1dB) | -94.8dB | -97dB | -58.7dB |
| Orpheus Zero | -88.7dB | -87.3dB | -56.8dB |
| Azur 640C V2 | -89.8dB | -91dB | -64.5dB |
| NAD C540 | -34.1dB | -26.3dB | -20.4dB |
The NAD has no headroom for intersample overs. Too bad as so many CD Masters are recorded too hot.
----
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:
There is a good symmetry meaning that the published specs were indeed pessimist. There is a little more noise than best in class, but we can very clearly see the 3 fundamental levels of the 16bits PCM code converted, so this is very good since many older R2R converters were only dreaming of that performance...
----
Other measurements (not shown):
- IMD AES-17 DFD "Analog" (18kHz & 20kHz 1:1) : -90.9dB
- IMD AES-17 DFD "Digital" (17'987Hz & 19'997Hz 1:1) : -74.3dB
- IMD AES-17 MD (41Hz & 7993Hz 4:1): -79.7dB
- IMD DIN (250Hz & 8kHz 4:1) : -76.6dB
- IMD CCIF (19kHz & 20kHz 1:1) : -74.2dB
- IMD SMPTE (60Hz & 17kHz 1:4) : -77.9dB
- IMD TDFD Bass (41Hz & 89Hz 1:1) : -111.1dB
- IMD TDFD (13'58Hz & 19841Hz 1:1) : -95.3dB
- Dynamic Range : 96.8dB (without dither @-60dBFS)
- Crosstalk: 100Hz (below -140dBr), 1kHz (below -140dBr), 10kHz (-122dBr)
- Pitch Error (GPSDO corrected) : 19'999.91Hz (19'997Hz requested) ie +145.5ppm
- Gapless playback : Yes
The Dynamic range is shy of 2dB compared to best in class, and of course still very good.
Crosstalk is extremely low, in the best in class category.
Pitch error is a high 145ppm+ which is unusual. The x'tal in use is said to be of a 30ppm precision per the service guide. So, I'd suspect that the coupling capacitors (20pF) have aged and would need a refresh, maybe.
----
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 overlayed the results with the Azur 640C V2:
The NAD is let down by the H2 distorsion it generates at this lower level. Not much of a concern though, at -92dB, especially being easily hidden second harmonic, but we are used to best in class results here.
----
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) |
| SMSL PL-200 | 18.7bits | 100% |
| OPPO BDP-95 | 18.7bits | 100% |
| SMSL PS-200 (from CD player) | 18.6bits | 99.47% |
| Denon DCD-900NE | 18.5bits | 98.93% |
| Orpheus Zero | 18.4bits | 98.40% |
| Azur 640C V2 | 18.3bits | 97.86% |
| 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% |
| Revox B-226S | 16.8bits | 89.94% |
| Accuphase DP-70 | 16.6bits | 88.77% |
| NAD C540 | 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% |
Again, the NAD is let down by the high H2 that it generates and it's the only reason. As a consequence, the above results look worse than they are in real life, but hey, that's all about this test.
Of course, harmonic distorsion that is H2 driven is the one we should be less concerned about. And to be transparent, let me add this measurement for once:
As you can see, besides the H2, there's not much to mention. Had the H2 been on par with the H4, this would qualify as best in class.
----
On demand from the community, I now add a "de-emphasis test" to verify that this flag is detected and the compliance with the expected de-emphasis curve.
When the curve is within specs, we should see 8dB less at 11kHz, which is exactly what we get with the NAD (better than specs).
NAD C540 - 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.
Here are the results:
| 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) | 1.5mm |
| Combined dropouts and smallest pitch | From 1.5µm & 1mm to 1.5µm & 2.4mm | 1mm |
| Successive dropouts | From 2x0.1mm to 2x3mm | 1.5mm |
I could see the interpolation mechanism kicking off as soon as with a 0.5mm gap, but I could not hear it. No "clicks" until 1.5mm and the drive did not stop reading even with 4mm dropouts (although it was skipping few seconds).
The above are decent results and if you have CDs in good condition, this is more than good enough.
NAD C540 - Digital output
Ok, so we get a decent CD player here, especially for the price. And to expect better from a modern DAC, we need a perfect digital output. Let's test that.
This is my standard 999.91Hz @0dBFS (no dither):
This is the same as the original WAV file that was used to create the CD track.
The 3DC test is nailed too, of course:
My ultimate proof of "perfect" digital output is when I reuse the intersample overs test at 5512.50Hz, with a phase shift of 67.5°, like I did for the TASCAM CD-200 review. This signal generates an overshoot of +0.69dB. And so, if the signal would be modified before being sent (by an ASRC for instance), it would show either a reduction of amplitude or we'd see some sort of saturation/increase of noise/distorsion. So here we go with the NAD via the Coax out:
No distortion and the dashboard shows +0.69dBFS as expected. No ASRC on the digital path here. SNR is only 95.5dB because there is rectangle dither in this test file (consuming half a bit of resolution).
So we get a "perfect" transport in case you're not happy with the internal DAC.
Conclusion
Besides a little higher than usual H2 at low level and high frequencies, I shall be happy with what I measured, considering this was a budget CD Player in 1999.
I liked the speed of the drive, fact that the digital output is "perfect", and I must say that the internal DAC will remain transparent to your ears even if not perfect. For the price, I thing there's not much more to desire.
Reliability, yeah, a familiar weak spot with NAD gear... The drive of this one had to be swapped out, but it’s running again, for the next quarter century, if we’re lucky
I hope you enjoyed this review and I wish you a nice "JeuDredi" as we say in the French part of Switzerland as we feel the weekend coming (combination of Jeudi (Thursday) and Vendredi (Friday), could be ThurFriday in English, I suppose).
Cheers.
Flo
Last edited:
Oh yes, the output voltage makes a difference, higher is ("sounds") better unless the gain is compensated before the signal reaches the amplifier.
