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NAD C658 measurements and teardown Q


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On 11/10/2020 at 8:42 AM, kukynas said:

first of all I'd like to just remind people about measurements and findings from ASR web where measurements and discussion started and based on which I made my own so I take Amirm's figures as reference point.

I came across same issues as he did in terms of inability to measure the unit under standard conditions so I had to overcome them but about that bit later 

 

before we start here are original measurements and findings from Amirm, what is more interesting is that the same findings were captured independently on 2 devices, node 2i and C658, what is even more interesting is that both devices even if in different price category exhibit similar performance and problems so I would assume (both owned by NAD) they share many similarities in terms of design of internals

node 2i is bit cleaner but with higher noise floor (most probably masking otherwise visible spikes like in C658) and C658 bit noisier but with lower noise floor and bit lower harmonics but more distorted  

 

https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-bluesound-node-2i-streamer.6631/

https://www.audiosciencereview.com/forum/index.php?threads/nad-c658-streaming-dac-review.12090/

 

1702795354_BluesoundNode2iToslinkInputCoaxoutputMeasurements.png.e75099ae23e3928eef86481d1bc22fad.png

1619811047_BluesoundNode2iNetworkedPlaybackMeasurements.png.0ce4619098aca0bedc6d55c80f7b03b7.png858264253_NADC658streamingpreamplifierDACAudioMeasurements.png.46aa7f67b433b3833737ca553e30c3bd.png

 

 

 

acquisition HW and SW

- RME ADI 2 PRO FS - instrument grade ADC/DAC

- Siglent SDS2102X Plus - precision DSO with software package

- Siglent SDM3065X  - precision 6.5 digits benchtop multimeter

- Arta and RMA analyser software 


before I show you the measurements something about setup and numbers, ADI 2 was connected to my PC via USB and controlled via ASIO drivers, C658 was connected to ADI2 via coax cable and output of the DAC part connected via XLR cables to input of the ADI 2, ARTA and RMA levels were set based on multimeter to ~4V, unfortunately I wasn't able to reliably calibrate ARTA's signal generators level so the numbers (RMS/THD etc) are bit off nevertheless the spectrum and pattern should be showing correct levels

I can't use external signal generator with ARTA exclusive mode so 1khz frequency fluctuate a bit but shouldn't be an issue once the signal is settled and averaged 

I can't measure SNR/DNR with ARTA so unfortunately we have to believe NAD and their figures, fortunately they usually underestimate their figures so we could believe them, I also can't measure SINAD so we have to believe Amirm's figures

I can't adjust range of div. in Arta so first 1khz of frequency takes half of the screen

RMA was used just to demonstrate how would you normally measure such device (in this case unable to do properly due to problems with locking signal and distortion somewhere in the unit) and read the measured figures automatically generated by RMA analyser, they look terrible 🤦‍♂️ 

 

RMA analyser:

 

1678501921_RMAanalysis.thumb.jpg.5075cfc8bfd8ddd57f5eee5aebe15aed.jpg

 

 

ARTA 1khz sine as is normally set, look at the pattern also shown in Amirm's first measurements 

 

Arta3.thumb.jpg.9d0c74a3131b8112d909d6f7bade2dfc.jpg

 

adjusted setting to overcome the problem shown above, no averaging...

 

Arta4.thumb.jpg.5d645912b23772a898e6add5adb20a59.jpg

 

final THD+N after averaging for both channels (red and green) if you look at the pattern and compare it to Amirm's measurements they are close (in his picture numbers are bit squashed)

 

1512910273_Arta1lineleveled.thumb.jpg.6c429f56f9a60ca313049bcdb9b9f53b.jpg

 

had to follow same setting as before so first lock the signal and than change it and let it run otherwise it wouldn't work, multitone again both channels

 

331298443_Arta1multitone.thumb.jpg.4c8d79709326c9029f8486bf2223d8ae.jpg

 

2 tone

 

412261761_Arta12tone.thumb.jpg.d045cd4fbf4f1fcd3b7826e0b906ce9e.jpg

 

 

jitter vs. ADI 2 (red c658) , ignore the even harmonics (generated by the signal in ARTA) again very close to Amirm's measurements

 

858866739_jittervs.RMEADI2PROFSlineleveled.thumb.jpg.4f20f78e54ef175c2d474aca63f8a558.jpg

 

I wanted to see FFT from the scope unfortunately I found out that the termination at the DAC end isn't quite sufficient so will have to redo once the new cable arrive, for now just quick and dirty screenshot, nothing what's stands out with limits to 350khz

  

1152264237_ScreenImg(9).png.781f028f1b12910d8bc6e312fc8ad380.png

 

 

  

that's about it, any questions shoot....

 

next we'll have a look under the lid but before here's some white paper from NAD of what to expect https://nadelectronics.com/wp-content/uploads/2018/10/NAD-C-658-White-Paperwhite.pdf

 

some quotes from the white paper

 

we should be excited right? 

 

I know what's there already but let's wait for tomorrow 😂😉

 

 

ASR has perpetual habit of using levels much higher than any commercial CD or stream contains. Why they do this is a topic all of its own.  

 

I would suggest to measure a commercial CD - lets say Swiss band Sonar's Tranceportation CD , you should get figures as shown. You should then use the much lower figure that appears as +/- 350mv RMS ( shown in light blue ) , that is then realistic in terms of actual level - and not  artificial as ASR insists on using,   to assess your NAD . 

 

You look to know the cutoff point where objective measurements can no longer properly assess what we hear. Using music, not generated sine waves, to subjectively assess can give even more insight , relative to other equipment. 

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Hi guys,   are you interested in measurements and tear down of this unit? I would do it anyway it's just matter of documenting it all and providing my findings, just let me know...  

first of all I'd like to just remind people about measurements and findings from ASR web where measurements and discussion started and based on which I made my own so I take Amirm's figures as referen

it's aliveeeee!!! lol  

12 hours ago, Snoopy8 said:

NAD is no different to other brands in reliability but sorry to hear about the C298.  Curious why you did not swap with another unit and try it.

 

You already know about the advantages of C658 and there is an owners thread here

The C658 does have HT bypass..  You can fix the volume of an input (page 13 of manual).

I sent the C298 back to be replaced, however the store first want to confirm the defect. Once I get a replacement, I can continue testing and see if I keep it and if I add the C658 to it. Reading your measurements and comments, it is sad that a company like NAD, who say they are dedicated to hifi, try to save a few bucks by using and constructing lesser quality parts .... I would easily pay 100 euros more just to get everything to work better together and get the max out of the DAC, etc.

Edited by Lars V
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On 18/12/2020 at 2:59 PM, Lars V said:

@kukynas thanks for all the work. I am currently also looking at the NAD C658. However, this thread and others, plus the fact that I just sent back the NAD C298 cause it turned off by itself every time after 4 hours running, is making me cautious of NAD products. 

 

haven't heard about Q issues with C658 so no reason to be worry about, all sw glitches were ironed out long time ago...

reg your C298 troubles, there is dedicated thread on ASR forum talking about the sudden turn off problem, NAD would replace your defecting units upon request so shouldn't be a problem, after fix no more issues...

 

 

14 hours ago, stereo coffee said:

ASR has perpetual habit of using levels much higher than any commercial CD or stream contains. Why they do this is a topic all of its own.  

 

I would suggest to measure a commercial CD - lets say Swiss band Sonar's Tranceportation CD , you should get figures as shown. You should then use the much lower figure that appears as +/- 350mv RMS ( shown in light blue ) , that is then realistic in terms of actual level - and not  artificial as ASR insists on using,   to assess your NAD . 

 

No idea what you mean by much higher levels than commercial CD, all analyser available on the market or their HW/SW counter parts like in my case using industry standards when measuring DUT's output which in case of DAC/preamp should be 2V unbalanced or 4V balanced to get -3db reference level, of course one can use much lower figures but that would mean comparing apples with oranges because you can't predict how high the preamp/dac output should be to drive everyone's amplifier hence the standard of 2/4V

are we usually listening with such high levels? most probably not but to keep consistency and measure proper capability of the DUT these are the figures set  

measuring commercial CD won't tell me anything as I don't have reference signal generated to compare it with, there's another thread about measurements of music playback/recording and impact of the ADC/DAC conversion but that doesn't show or prove how good or bad the DUT is...

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3 hours ago, kukynas said:

 

haven't heard about Q issues with C658 so no reason to be worry about, all sw glitches were ironed out long time ago...

reg your C298 troubles, there is dedicated thread on ASR forum talking about the sudden turn off problem, NAD would replace your defecting units upon request so shouldn't be a problem, after fix no more issues...

 

 

 

No idea what you mean by much higher levels than commercial CD, all analyser available on the market or their HW/SW counter parts like in my case using industry standards when measuring DUT's output which in case of DAC/preamp should be 2V unbalanced or 4V balanced to get -3db reference level, of course one can use much lower figures but that would mean comparing apples with oranges because you can't predict how high the preamp/dac output should be to drive everyone's amplifier hence the standard of 2/4V

are we usually listening with such high levels? most probably not but to keep consistency and measure proper capability of the DUT these are the figures set  

measuring commercial CD won't tell me anything as I don't have reference signal generated to compare it with, there's another thread about measurements of music playback/recording and impact of the ADC/DAC conversion but that doesn't show or prove how good or bad the DUT is...

 

Thanks for that, your reply contains so much to discuss.  We can reliably predict how high a commercial CD's output is, which is    +/-350mv RMS.  To do the same where you are, load up Audacity and allow it to read the level of your CD - the graduation scale in fractions of RMS, can  then can be seen in light blue. The peak level is far higher seen in dark blue, but we are only interested in the light blue area, as it gives us a basis to compare as you say apples and oranges, ....  in my reply apples are commercial CD levels, and oranges are power amplifier sensitivity levels. 

 

If we can agree that the source component contains the least distortion, and subjectively the best chance of hearing the actual commercial CD as it was recorded, ...are we on the same page so to speak ?  ....    a good power amplifier should you would expect, ( as audiophiles we should insist on )  for least distortion and hence best possible result,  similarly match its RMS sensitivity to very close to that same level, like this power amplifier below: 

 

In between, we can then use attenuation that does least possible change to the source audio, which is in electronics terms just resistance.

But if we begin using reactance, with anything other than resistance ... and worse change level away from the source component level, then say goodbye to ever hearing the source component properly. 

 

hence why you need to measure your NAD at +/- 350mv RMS 

 

We can now perhaps see the 2v/4v levels are those of the potential output the player has, but are NEVER representative of  the RMS level commercial CD's contain.... we should therefore always reject measurements using such figures,  that are totally unrealistic, and instead always use measurements that bear relationship to the source components we use daily.   We then have a level playing field 🙂 , and not like this 🙃 that ASR keeps on misleading with.

 

  

 

 

 

Screenshot from 2020-12-20 07-47-19.png

Screenshot from 2020-09-29 23-26-20.png

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14 hours ago, stereo coffee said:

 

Thanks for that, your reply contains so much to discuss.  We can reliably predict how high a commercial CD's output is, which is    +/-350mv RMS.  To do the same where you are, load up Audacity and allow it to read the level of your CD - the graduation scale in fractions of RMS, can  then can be seen in light blue. The peak level is far higher seen in dark blue, but we are only interested in the light blue area, as it gives us a basis to compare as you say apples and oranges, ....  in my reply apples are commercial CD levels, and oranges are power amplifier sensitivity levels. 

 

If we can agree that the source component contains the least distortion, and subjectively the best chance of hearing the actual commercial CD as it was recorded, ...are we on the same page so to speak ?  ....    a good power amplifier should you would expect, ( as audiophiles we should insist on )  for least distortion and hence best possible result,  similarly match its RMS sensitivity to very close to that same level, like this power amplifier below: 

 

In between, we can then use attenuation that does least possible change to the source audio, which is in electronics terms just resistance.

But if we begin using reactance, with anything other than resistance ... and worse change level away from the source component level, then say goodbye to ever hearing the source component properly. 

 

hence why you need to measure your NAD at +/- 350mv RMS 

 

We can now perhaps see the 2v/4v levels are those of the potential output the player has, but are NEVER representative of  the RMS level commercial CD's contain.... we should therefore always reject measurements using such figures,  that are totally unrealistic, and instead always use measurements that bear relationship to the source components we use daily.   We then have a level playing field 🙂 , and not like this 🙃 that ASR keeps on misleading with.

 

 

maybe we misunderstood each other but 2V/4V output level has nothing to do with music DNR scale in volts and ASR doesn't misleading anyone, as said it's industry standard, even manufactures showing their specs accordingly (below in red box) so if I'm evaluating potential improvement of my DAC/preamp I have to use reference level which in this case is 2V/4V to be able to compare figures before and after

 

506154001_outputlevelformeasurement.thumb.jpg.279b48b66f4ff6235b59395d8a594e47.jpg

 

 

 

maybe @MLXXX can shed some light on audacity as I'm not expert with it but again I think we are talking apples and oranges here, there's dedicated thread about DAC evaluation using music file via ADC/DAC process and it's impact so maybe it'll be more suitable to continue there

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1 hour ago, kukynas said:

 

maybe we misunderstood each other but 2V/4V output level has nothing to do with music DNR scale in volts and ASR doesn't misleading anyone, as said it's industry standard, even manufactures showing their specs accordingly (below in red box) so if I'm evaluating potential improvement of my DAC/preamp I have to use reference level which in this case is 2V/4V to be able to compare figures before and after

 

506154001_outputlevelformeasurement.thumb.jpg.279b48b66f4ff6235b59395d8a594e47.jpg

 

 

 

maybe @MLXXX can shed some light on audacity as I'm not expert with it but again I think we are talking apples and oranges here, there's dedicated thread about DAC evaluation using music file via ADC/DAC process and it's impact so maybe it'll be more suitable to continue there

ASR is misleading everyone with its measurements because the figures of RMS level they measure with is,  5.71 x higher than any commercial CD contains.  2v / 0.350v =5.71

 

Can you now see that the RMS level leaving any given CD player device IS always limited to the level of the CD itself ie  is +/- 350mv , and is NEVER   2v or 4v, which explains why it makes sense to always measure accurately, with actual conditions, rather than with levels that will never be achieved.

 

If we taking another example, tested cars at 5.71x their maximum speed by perhaps dropping them from space into a designated target zone, and attributed their ability at say if the average car does 180kmh max, at then 1087 kmh, we would be laughed at, and rightly so.   

 

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On 20/12/2020 at 9:36 PM, stereo coffee said:

ASR is misleading everyone with its measurements because the figures of RMS level they measure with is,  5.71 x higher than any commercial CD contains.  2v / 0.350v =5.71

 

I am mystified by your line of argument.

 

You appear to be suggesting that audiophile electronic devices should be tested based on some sort of averaged out amplitude over time.  The closest approach to that I can think of a is a music power rating for a power amplifier. More generally, such an approach would be quite arbitrary, as there is no agreed figure as to what "averaged out" RMS level recordings of music contain.  Pop music tends to use a narrower dynamic range than classical music.  However some movements in a piece of classical music might be loud almost throughout; or conversely soft almost throughout.  Some organ music will contain sustained low frequency waveforms close to sine waves and with very high RMS levels.

 

In terms of using the editor Audacity, the ratio between the parts of the waveform coloured a lighter shade of blue (the RMS values) and the peaks (coloured a darker shade of blue) will of course vary depending on the particular recording.  

 

Longstanding standard practice is to measure  audiophile devices at full nominal RMS output (or input) at 1kHz . The fact that a mastered recording of music would never consist of a sustained 1kHz sinewave is beside the point. The device needs to be capable of passing at least a few cycles  at the full nominal output level without excessive distortion. This capability is needed to handle transients. It is no good if a device clips when called upon to deliver the full nominal output level.

 

Have I misinterpreted your line of argument, @stereo coffee

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6 hours ago, MLXXX said:

 

I am mystified by your line of argument.

 

You appear to be suggesting that audiophile electronic devices should be tested based on some sort of averaged out amplitude over time.  The closest approach to that I can think of a is a music power rating for a power amplifier. More generally, such an approach would be quite arbitrary, as there is no agreed figure as to what "averaged out" RMS level recordings of music contain.  Pop music tends to use a narrower dynamic range than classical music.  However some movements in a piece of classical music might be loud almost throughout; or conversely soft almost throughout.  Some organ music will contain sustained low frequency waveforms close to sine waves and with very high RMS levels.

 

In terms of using the editor Audacity, the ratio between the parts of the waveform coloured a lighter shade of blue (the RMS values) and the peaks (coloured a darker shade of blue) will of course vary depending on the particular recording.  

 

Longstanding standard practice is to measure  audiophile devices at full nominal RMS output (or input) at 1kHz . The fact that a mastered recording of music would never consist of a sustained 1kHz sinewave is beside the point. The device needs to be capable of passing at least a few cycles  at the full nominal output level without excessive distortion. This capability is needed to handle transients. It is no good if a device clips when called upon to deliver the full nominal output level.

 

Have I misinterpreted your line of argument, @stereo coffee

No not tested, rather manufactured and tested, to levels of sensitivity that match lets say within 10% of the actual RMS voltage levels available in media.  This does not  encourage ignorance of peaks in music. Quite the opposite audiophile equipment should accommodate highest peaks, and have bandwidth well beyond the Nyquist determinations.    

 

Quite a few manufacturers do this already and have been doing so since 1967 - Quad the UK manufacturer being a great example, their typical sensitivity being 500mv input for full output, which matches today's media sources. 

 

The majority of amplifiers sold today, and yesterday are voltage amplifiers - nothing more nothing less, they simply respond to the input voltage that is needed for delivering power in a 8 ohm resistance at a certain frequency usually 1khz ,  hence if used with media that does not match their sensitivity, the opportunity of available power delivery is very much lessened.  And if used with equipment increasing the source voltage level then  has reactance added in varying degrees.

 

 

 

 

 

 

 

 

 

 

 

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  • 1 month later...

a new day (or maybe 3 months) has come and we have some progress...

 

finally was able to obtain decent signal generator to be able to measure streaming performance (instead of coax as with all previous tests) so below some figures, overall measurements of streaming module reveal lower low noise distortion and jitter side bands, on the other hand slightly higher harmonics, I can't perform entire set of measurements but this should give us enough clue of what to expect, just a note, all my measurements are undithered for those interested

In general, streaming files over network should provide better result than using C658 as coax fed DAC

in the meantime I performed stage 2 upgrade of the analog PSU rails but haven't seen significant improvements, something is still limiting factor but I expect to see some improvements after facelift of the I/V and buffer stage, fingers x

 

469206834_Arta1newULNregonanalogstagestreamingtest.thumb.jpg.cfcad33ba93521be6f36a905bb5e23b8.jpg2009793580_Arta1jitterPSUwithouttonecontrolnewregsonanalogstagestreamingtest.thumb.jpg.b13897cd6b674e44028235a40c934ede.jpg1044909898_Arta12tonenewPSUandnewregsstreamingtest.thumb.jpg.a268f14b5733853d17a8036a6d28a54b.jpg

 

with dithered signal, higher noise floor lower harmonics

 

823774463_Arta1newULNregonanalogstagestreamingtestditheredsignal.thumb.jpg.6ce71aa5b05896276dcb6b56c046ed6a.jpg

 

noise floor of the unit no signal playing

 

899122080_Arta1newULNregonanalogstagestreamingtestnoisefloor.thumb.jpg.84f0beeaf6e373aadcfe32edab685566.jpg

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Hi Dan,

I have found your very interesting project and I'm also owner of a C658 and have been doing some of the same thought of modifiying the PSU, OPA, clock.

Now I have some questions to your detailed teardown of the C658.

- Why do they have so 12 pin connector between the SMPS and mainboard? It seems like there is only 14V DC and ground!

- The XP Power SMPS (looks like ECM model) that you have chosen are very compact but looking at the R&N then it is 1% pk2pk which is normal for SMPS or have I missed something about those SMPSs?

- Do you have a picture where you connected your 5V DCs when having removed varius buck converters?

- It seems like there many NE5532 OPA (I counted 11) why so many? Have you replaced them all with OPA1612?

- Are there any low quality caps in the output signal path?

- I was thinking of removing the crystal and install a reference clock instead. What is your opnion abou that?
 

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1 hour ago, Puresound said:

Hi Dan,

I have found your very interesting project and I'm also owner of a C658 and have been doing some of the same thought of modifiying the PSU, OPA, clock.

Now I have some questions to your detailed teardown of the C658.

- Why do they have so 12 pin connector between the SMPS and mainboard? It seems like there is only 14V DC and ground!

- The XP Power SMPS (looks like ECM model) that you have chosen are very compact but looking at the R&N then it is 1% pk2pk which is normal for SMPS or have I missed something about those SMPSs?

- Do you have a picture where you connected your 5V DCs when having removed varius buck converters?

- It seems like there many NE5532 OPA (I counted 11) why so many? Have you replaced them all with OPA1612?

- Are there any low quality caps in the output signal path?

- I was thinking of removing the crystal and install a reference clock instead. What is your opnion abou that?
 

 

Hi,

 

- no idea and yes, only 14VDC + ground

- yes, R&N is normal like for any other SMPS, the only reason why I chosen this one instead of Delta with 5x lower R&N is size and regulation, you need to get down to 14V from your typical 15V output via output trim and to be able to squeeze two of them on 1 PCB, one for 14V and the other for 5V (7V output SMPS post regulated with 5V ULN reg) 

- see picture below, basically same input as with buck converter via 8 pin connector as I wanted to be able to disconnect it during further upgrades + I didn't wanna cut any traces if I would have to go back and solder back the buck converter 

- I/V stage + buffer stage (balanced + unbalanced) + headphone amp and not yet, planning to do next but only for I/V and balanced buffer stage, don't care about the rest

- nope

- wouldn't do it, you won't find better clock in this package with same fq and even if than more beneficial is upgrade of the reg with clean power as I did, picture below

 

as you can see from measurements the only benefit in my POV is better reg for clock, all the other upgrades didn't bring any measurable improvement so if I'm doing it again the only upgrade would be reg for clock, now coz I don't have previous measurements of the streamed signal (instead of coax) before upgrade I can't confirm and compare if the latest upgrade of the analog PSU rails helped but if yes again the benefit is very small

As mentioned in my earlier post you can't change all buck converters due to fact they are driven by MCU for stand by functionality and you won't find linear reg counterpart (I tried) with 3A output so all the potential benefits by changing only one or few of them are basically useless as shown in my measurements.

lets wait for my last attempt (opamps) and see what (if) contributes the most to the overall result

 

IMG_2901.thumb.JPG.112eec8bebb0655d47336ea192d35805.JPGIMG_2902.thumb.JPG.4e317bbf275e7b2b5b875c87884cb06c.JPG

 

 

 

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On 12/02/2021 at 1:36 PM, kukynas said:

a new day (or maybe 3 months) has come and we have some progress...

 

finally was able to obtain decent signal generator to be able to measure streaming performance (instead of coax as with all previous tests) so below some figures, overall measurements of streaming module reveal lower low noise distortion and jitter side bands, on the other hand slightly higher harmonics, I can't perform entire set of measurements but this should give us enough clue of what to expect, just a note, all my measurements are undithered for those interested

In general, streaming files over network should provide better result than using C658 as coax fed DAC

in the meantime I performed stage 2 upgrade of the analog PSU rails but haven't seen significant improvements, something is still limiting factor but I expect to see some improvements after facelift of the I/V and buffer stage, fingers x

 

469206834_Arta1newULNregonanalogstagestreamingtest.thumb.jpg.cfcad33ba93521be6f36a905bb5e23b8.jpg2009793580_Arta1jitterPSUwithouttonecontrolnewregsonanalogstagestreamingtest.thumb.jpg.b13897cd6b674e44028235a40c934ede.jpg1044909898_Arta12tonenewPSUandnewregsstreamingtest.thumb.jpg.a268f14b5733853d17a8036a6d28a54b.jpg

 

with dithered signal, higher noise floor lower harmonics

 

823774463_Arta1newULNregonanalogstagestreamingtestditheredsignal.thumb.jpg.6ce71aa5b05896276dcb6b56c046ed6a.jpg

 

noise floor of the unit no signal playing

 

899122080_Arta1newULNregonanalogstagestreamingtestnoisefloor.thumb.jpg.84f0beeaf6e373aadcfe32edab685566.jpg

Hi Dan,

 

Interesting that it did not help to upgrade analog PSU rails. It is the LM317s and LM337s? How does NAD convert the 14V to +/- x Volt for OPAs? I have seen in M12 that they use LM2611 but I can't spot it around the LM3x7s

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On 14/02/2021 at 12:41 PM, kukynas said:

 

Hi,

 

- no idea and yes, only 14VDC + ground

- yes, R&N is normal like for any other SMPS, the only reason why I chosen this one instead of Delta with 5x lower R&N is size and regulation, you need to get down to 14V from your typical 15V output via output trim and to be able to squeeze two of them on 1 PCB, one for 14V and the other for 5V (7V output SMPS post regulated with 5V ULN reg) 

- see picture below, basically same input as with buck converter via 8 pin connector as I wanted to be able to disconnect it during further upgrades + I didn't wanna cut any traces if I would have to go back and solder back the buck converter 

- I/V stage + buffer stage (balanced + unbalanced) + headphone amp and not yet, planning to do next but only for I/V and balanced buffer stage, don't care about the rest

- nope

- wouldn't do it, you won't find better clock in this package with same fq and even if than more beneficial is upgrade of the reg with clean power as I did, picture below

 

as you can see from measurements the only benefit in my POV is better reg for clock, all the other upgrades didn't bring any measurable improvement so if I'm doing it again the only upgrade would be reg for clock, now coz I don't have previous measurements of the streamed signal (instead of coax) before upgrade I can't confirm and compare if the latest upgrade of the analog PSU rails helped but if yes again the benefit is very small

As mentioned in my earlier post you can't change all buck converters due to fact they are driven by MCU for stand by functionality and you won't find linear reg counterpart (I tried) with 3A output so all the potential benefits by changing only one or few of them are basically useless as shown in my measurements.

lets wait for my last attempt (opamps) and see what (if) contributes the most to the overall result

 

IMG_2901.thumb.JPG.112eec8bebb0655d47336ea192d35805.JPGIMG_2902.thumb.JPG.4e317bbf275e7b2b5b875c87884cb06c.JPG

 

 

 

Hi Dan,

 

Thanks for sharing your pictures and experience.

I have some followup questions.

I plan to have ultra low noise voltage (like Belleson SPX or Sparkos SSXX) after the 2 SMPS to generate 14V and 5V, respectively.

I can see you took out the U807 and connected the 5V reference - what parts does it provide voltage to? What about U806 and U805?

Did you remove some component to install the reg for the clock?

I forgot the Headphone output which assume would be OPA U104, 106, 108, 109, 110? I'm not interested in that but will plan on doing the other when I hear your experience afther having changed those

 

 

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3 hours ago, Puresound said:

Hi Dan,

 

Interesting that it did not help to upgrade analog PSU rails. It is the LM317s and LM337s? How does NAD convert the 14V to +/- x Volt for OPAs? I have seen in M12 that they use LM2611 but I can't spot it around the LM3x7s

 

yes LM3XX , via diode and than regs down to +/-12V

 

2 hours ago, Puresound said:

Hi Dan,

 

Thanks for sharing your pictures and experience.

I have some followup questions.

I plan to have ultra low noise voltage (like Belleson SPX or Sparkos SSXX) after the 2 SMPS to generate 14V and 5V, respectively.

I can see you took out the U807 and connected the 5V reference - what parts does it provide voltage to? What about U806 and U805?

Did you remove some component to install the reg for the clock?

I forgot the Headphone output which assume would be OPA U104, 106, 108, 109, 110? I'm not interested in that but will plan on doing the other when I hear your experience afther having changed those

 

 

 

- don't know Belleson but Sparkos doesn't have enough current output, you need 3A output regs, I bought mine voltage reference regs (and many other PSUs) from Kim over here  ULN-HC78A Ultra Low Noise Positive Regulator 2.5V~30V Output High Current Type | eBay

- if you have bigger budget this is SOTA low dropout voltage reg capable of 6A output ULN-LD78 Ultra Low Noise, LDO(Very Low Dropout) Regulator 1.25V ~ 30V | eBay

- to DAC chip, input board regs and most probably part of the DSP board, U806 is 5v bc for DSP board, U805 is 3.3V for add on cards and don'w know what else, there is another bc underneath the board no idea what for  

- as mentioned earlier I couldn't measure any improvement by changing U807 to ULN reg so the old buck converter going back and would recommend to keep it there, no point in spending money with no benefit, once it's back I will connect my lab linear PSU to see if I can get rid off those psu spikes, if yes then linear PSU is potentially on the table

- yes, resistor (R740 next to the oscillator) which connects the original reg to the oscillator

- yes except U110, no chance to trace that opa, no idea if it's part of the IV but just in case I changed that too...

 

as shown below with changing OPAs we get 5-10db lower harmonics but that's it, I think we are hitting the NRC chip distortion so not much more gain to be expected means no reason to spend more time nor money on it

 

PSU distortion and bottom harmonics are around -135db so hardly can contribute to the sound, main harmonics are there but in low level at nearly full scale (music content never gets to such amplitude) so I'm not so worried about them and as previously mentioned the overall presentation sounds nearly identical to my RME Adi 2 Pro fs so pretty good result I would say...

 

344681032_Arta1newULNregonanalogstagestreamingtestIVstagebuffer.thumb.jpg.c16c3b781d364e0a0afbc4be6f35054c.jpg

 

 

 

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On 24/12/2020 at 6:41 AM, stereo coffee said:

No not tested, rather manufactured and tested, to levels of sensitivity that match lets say within 10% of the actual RMS voltage levels available in media. 

 

Why RMS?

 

On 24/12/2020 at 6:41 AM, stereo coffee said:

The majority of amplifiers sold today, and yesterday are voltage amplifiers - nothing more nothing less, they simply respond to the input voltage that is needed for delivering power in a 8 ohm resistance at a certain frequency usually 1khz ,  hence if used with media that does not match their sensitivity, the opportunity of available power delivery is very much lessened.

 

I think you write this in a strange way that will confuse many..... but I agree with you.

 

Gain structure is of upmost importance......    otherwise we will need to add amplifying (or de-amplifying) components in between our source and (ideally a single) gain stage.....  which will likely have unwanted reactance.

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2 hours ago, kukynas said:

 

yes LM3XX , via diode and than regs down to +/-12V

 

 

- don't know Belleson but Sparkos doesn't have enough current output, you need 3A output regs, I bought mine voltage reference regs (and many other PSUs) from Kim over here  ULN-HC78A Ultra Low Noise Positive Regulator 2.5V~30V Output High Current Type | eBay

- if you have bigger budget this is SOTA low dropout voltage reg capable of 6A output ULN-LD78 Ultra Low Noise, LDO(Very Low Dropout) Regulator 1.25V ~ 30V | eBay

- to DAC chip, input board regs and most probably part of the DSP board, U806 is 5v bc for DSP board, U805 is 3.3V for add on cards and don'w know what else, there is another bc underneath the board no idea what for  

- as mentioned earlier I couldn't measure any improvement by changing U807 to ULN reg so the old buck converter going back and would recommend to keep it there, no point in spending money with no benefit, once it's back I will connect my lab linear PSU to see if I can get rid off those psu spikes, if yes then linear PSU is potentially on the table

- yes, resistor (R740 next to the oscillator) which connects the original reg to the oscillator

- yes except U110, no chance to trace that opa, no idea if it's part of the IV but just in case I changed that too...

 

as shown below with changing OPAs we get 5-10db lower harmonics but that's it, I think we are hitting the NRC chip distortion so not much more gain to be expected means no reason to spend more time nor money on it

 

PSU distortion and bottom harmonics are around -135db so hardly can contribute to the sound, main harmonics are there but in low level at nearly full scale (music content never gets to such amplitude) so I'm not so worried about them and as previously mentioned the overall presentation sounds nearly identical to my RME Adi 2 Pro fs so pretty good result I would say...

 

344681032_Arta1newULNregonanalogstagestreamingtestIVstagebuffer.thumb.jpg.c16c3b781d364e0a0afbc4be6f35054c.jpg

 

 

 

Hi,

 

I have tried to find the setup you are describing. So there is a virtual ground for creating the +/-7V like the enclosed figure?

The Belleson has 3A capabillity see link https://www.belleson.com/store/SPX-Max-Performance/SPX78-Positive-Output

Also nice Regs that you have found. I have previously looked at their clocks.

It sounds like with the OPAs, ref reg on the clock and possible LPS then it becomes a very attractive og good sounding preamp combined with all its nice fetures builtin.

Have you experimented with discrete OPAs instead of OPA 1612 - like Sparkos, Burson og NewclassD/Dexa?

 

 

Dual power supply 2.jpg

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4 hours ago, davewantsmoore said:

 

Why RMS?

 

 

I think you write this in a strange way that will confuse many..... but I agree with you.

 

Gain structure is of upmost importance......    otherwise we will need to add amplifying (or de-amplifying) components in between our source and (ideally a single) gain stage.....  which will likely have unwanted reactance.

When matching sensitivity ,  0.316v RMS is the consumer equipment line level standard.   https://en.wikipedia.org/wiki/Line_level

which can also be expressed as peak to peak, or indeed dbv , or +dbu,   RMS is though a common form for quoting amplifier sensitivity. 

 

Gain structure as you say is of utmost importance,  here we see in light blue RMS of a flac file. ( Swiss band Sonar - playing flat out )

Playing this through a passive system with amplifier sensitivity ( quad 306 ) of 0.375v RMS, there is then much benefit in not adding reactance by changing level, to suit a different sensitivity.   The source then matches to the power amp, and all that is needed in between is passive resistance to attenuate. 

 

 

 

Screenshot from 2021-02-17 16-16-39.png

Screenshot from 2021-02-17 16-25-13.png

Screenshot from 2020-12-20 07-46-25.png

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7 hours ago, Puresound said:

Hi,

 

I have tried to find the setup you are describing. So there is a virtual ground for creating the +/-7V like the enclosed figure?

The Belleson has 3A capabillity see link https://www.belleson.com/store/SPX-Max-Performance/SPX78-Positive-Output

Also nice Regs that you have found. I have previously looked at their clocks.

It sounds like with the OPAs, ref reg on the clock and possible LPS then it becomes a very attractive og good sounding preamp combined with all its nice fetures builtin.

Have you experimented with discrete OPAs instead of OPA 1612 - like Sparkos, Burson og NewclassD/Dexa?

 

 

Dual power supply 2.jpg

 

Hi,

don't think so, it looks each + and - has it's own traces and diode (via D800) seems to be only on "-" rail but I didn't paid too much attention to it.

sure Belleson is 3A I just never used this reg hence "I don't know", I was referring to Sparkos in terms of output requirements

I'm using his design for nearly a decade and always happy with his products

yes, definitely especially if you consider there's no other product (yet) on the market with all those features 

yes, in my previous Sabre DAC, Sparkos and Burson, sparkos were OK but nothing outstanding to be paying premium for, burson was crap, one of them melted down in that plastic tower 😂

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4 hours ago, stereo coffee said:

0.316v RMS is the consumer equipment line level standard.

 

If we are testing the performance of a circuit.... we care about the performance at all levels, not just at the average.

 

It is not misleading to test a device with 2V.     If people misunderstand what the test means the that is their fault...... so the "people doing tests at ASR with 2V" are not being "misleading".

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24 minutes ago, davewantsmoore said:

 

If we are testing the performance of a circuit.... we care about the performance at all levels, not just at the average.

 

It is not misleading to test a device with 2V.     If people misunderstand what the test means the that is their fault...... so the "people doing tests at ASR with 2V" are not being "misleading".

They are misleading everyone,  IMO when they totally fail and outright refuse,  also to concurrently test,  at actual levels.

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3 hours ago, kukynas said:

 

Hi,

don't think so, it looks each + and - has it's own traces and diode (via D800) seems to be only on "-" rail but I didn't paid too much attention to it.

sure Belleson is 3A I just never used this reg hence "I don't know", I was referring to Sparkos in terms of output requirements

I'm using his design for nearly a decade and always happy with his products

yes, definitely especially if you consider there's no other product (yet) on the market with all those features 

yes, in my previous Sabre DAC, Sparkos and Burson, sparkos were OK but nothing outstanding to be paying premium for, burson was crap, one of them melted down in that plastic tower 😂

Hi,

Thanks again.

Sorry I can't figure out the setup with one diode and with a LM337 handling the "-" rail?

There are 2pcs of LM317 and LM337 right? why having 2 sets of Dual voltage PSU?

Yes I have not been able to find another Preamp with MQA, Dirac, direct support for streaming service and HDMI input/output so I can get video streaming audio sound into the system as well without having a seperate system for that.

As I haven't open the box yet. what is the space between mainboard and DSP board on top?

I have not heard so much good about Burson either as the sound is not natural

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11 minutes ago, Puresound said:

Hi,

Thanks again.

Sorry I can't figure out the setup with one diode and with a LM337 handling the "-" rail?

There are 2pcs of LM317 and LM337 right? why having 2 sets of Dual voltage PSU?

Yes I have not been able to find another Preamp with MQA, Dirac, direct support for streaming service and HDMI input/output so I can get video streaming audio sound into the system as well without having a seperate system for that.

As I haven't open the box yet. what is the space between mainboard and DSP board on top?

I have not heard so much good about Burson either as the sound is not natural

 

I will check the circuit and mark the traces of the - rail.

One set is for opamps (+/-12v) and the other set for NRC chip (+/- 7.5v)  maybe even for headphone opamps but didn't check that so not sure

I think space is around 30mm but can measure it properly once I'm back home from work

yep and sounded distorted, there's really no need to pay extra money for luxury/boutique opamps if you can get cheap, reliable and low distortion one from TI which is all you need in something doing D/A conversion

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4 hours ago, stereo coffee said:

They are misleading everyone,  IMO when they totally fail and outright refuse,  also to concurrently test,  at actual levels.

 

I don't know why it is so hard to understand the logic, ASR, Stereophile, all other audio publications including manufacturers of products all just follows industry standard set by orgs like AES, EBU, ITU etc. which specifies at which level the measurements supposed to be performed, if you don't like it go and complain to those organization and ask them to change it 

It's like complaining that car manufactures in EU (don't know the rest) providing fuel consumption at 110km/h misleading consumers coz it's old standard and highway limit for last 3 decades is 130km/h, should I complain about it to VW and all the other car manufactures that they are misleading customers as there is either 90km/h limit for country roads or 130km/h limit for highway so their 110km/h limit is completely useless? no, coz they are just following standard set by car industry to be compliant 

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4 hours ago, kukynas said:

 

I will check the circuit and mark the traces of the - rail.

One set is for opamps (+/-12v) and the other set for NRC chip (+/- 7.5v)  maybe even for headphone opamps but didn't check that so not sure

I think space is around 30mm but can measure it properly once I'm back home from work

yep and sounded distorted, there's really no need to pay extra money for luxury/boutique opamps if you can get cheap, reliable and low distortion one from TI which is all you need in something doing D/A conversion

That would be great. I just wonder how to get from +14V to +/-12 V without any "conversion/chip" .

I hope you are right about the space between the boards as this should be sufficient.

So you don't think there is sound effect from the luxury OPA. So which OPA chips do you think performs best?

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3 hours ago, kukynas said:

 

I don't know why it is so hard to understand the logic, ASR, Stereophile, all other audio publications including manufacturers of products all just follows industry standard set by orgs like AES, EBU, ITU etc. which specifies at which level the measurements supposed to be performed, if you don't like it go and complain to those organization and ask them to change it 

It's like complaining that car manufactures in EU (don't know the rest) providing fuel consumption at 110km/h misleading consumers coz it's old standard and highway limit for last 3 decades is 130km/h, should I complain about it to VW and all the other car manufactures that they are misleading customers as there is either 90km/h limit for country roads or 130km/h limit for highway so their 110km/h limit is completely useless? no, coz they are just following standard set by car industry to be compliant 

It is illogical to measure equipment at 12.69 x  levels,  ( 4 V RMS ASR typical    /  0.315 RMS line level standard )  greater than the mediums being played by equipment,  actually attain in normal use.

 

Drawing comparison to your reply, like testing a VW at  1395.9 kph, ( 110kph x 12.69  ) and claiming,  that is just following the standard of compliance. 

 

 

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2 hours ago, Puresound said:

That would be great. I just wonder how to get from +14V to +/-12 V without any "conversion/chip" .

I hope you are right about the space between the boards as this should be sufficient.

So you don't think there is sound effect from the luxury OPA. So which OPA chips do you think performs best?

- you've been right, it's S10U45S reverse rectifier fed by LM26670 (from the other side of the board, that magic bc I wasn't sure it's meaning) 

- 27mm 

- unless you are looking for some specific voicing (no idea which) to your sound I don't think you need luxury OPA, currently installed is OPA1612, previously been using LM4562 in other projects with same success, both low noise, low distortion, high PSRR and CMRR opamps   

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6 minutes ago, stereo coffee said:

It is illogical to measure equipment at 12.69 x  levels,  ( 4 V RMS ASR typical    /  0.315 RMS line level standard )  greater than the mediums being played by equipment,  actually attain in normal use.

 

Drawing comparison to your reply, like testing a VW at  1395.9 kph, ( 110kph x 12.69  ) and claiming,  that is just following the standard of compliance. 

 

 

 

they all follow the standards set by industry, no matter if logical or not or to your or mine liking but that doesn't mean they (reviewers or publications) are misleading people or customers 

yes, we can complain that current standards aren't useful or up to date but that's completely different story directed to different folks, those who sets the standards  

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2 minutes ago, kukynas said:

 

they all follow the standards set by industry, no matter if logical or not or to your or mine liking but that doesn't mean they (reviewers or publications) are misleading people or customers 

yes, we can complain that current standards aren't useful or up to date but that's completely different story directed to different folks, those who sets the standards  

What is the line level RMS voltage standard set by industry for consumer use  ?  ... you can see it here.  , and you can measure any given CD using Audacity as I previously showed above  , that shows mediums attain no higher RMS  level.  ( seen in light blue ) , and mediums are rigidly  compliant to the requirements of the line level standard.  

 

Measuring 12.69 x greater, there is no justification or proper reason for it.  Rather it falls,  unless addressed by countering its stance,  into a disinformation strategy, which sadly until addressed, is misleading to anyone wanting information about how equipment actually performs 

 

 

 

 

 

 

 

Screenshot from 2021-02-17 16-16-39.png

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18 minutes ago, stereo coffee said:

What is the line level RMS voltage standard set by industry for consumer use  ?  ... you can see it here.  , and you can measure any given CD using Audacity as I previously showed above  , that shows mediums attain no higher RMS  level.  ( seen in light blue ) , and mediums are rigidly  compliant to the requirements of the line level standard.  

 

Measuring 12.69 x greater, there is no justification or proper reason for it.  Rather it falls,  unless addressed by countering its stance,  into a disinformation strategy, which sadly until addressed, is misleading to anyone wanting information about how equipment actually performs 

 

 

 

 

 

 

 

Screenshot from 2021-02-17 16-16-39.png

 

geeez, again your you line level output? has nothing to do with testing condition, have you ever heard about sustainability threshold used during testing? have you ever been or worked for company producing equipment or product? how they evaluate if the product sustain not only nominal (standard) value but also peak value what ever it is? do you think i.e. car tire is tested to sustain eg only 30 psi or several times higher to make sure it'll survive under every possible condition? or engine or high pressure bottle or or or.

that has nothing to do with your nominal (typical) values but values set for testing purposes by industry organisation and that's what we are trying to explain you, you can't compare your nominal (typical) value and it doesn't matter if it's in RMS or PTP or what ever but value used for testing purposes to evaluate DUT

I'm not going to comment it any further, please do not reply, if you wanna continue please open your own thread where people can talk about it, this thread is dedicated to NAD C658 not why is this or that standard wrong.

Thank you...

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16 hours ago, kukynas said:

- you've been right, it's S10U45S reverse rectifier fed by LM26670 (from the other side of the board, that magic bc I wasn't sure it's meaning) 

- 27mm 

- unless you are looking for some specific voicing (no idea which) to your sound I don't think you need luxury OPA, currently installed is OPA1612, previously been using LM4562 in other projects with same success, both low noise, low distortion, high PSRR and CMRR opamps   

Hi

 

Amazing how you can "decode" the board, so the LM2670 BC chip is underneath the D800 on the back of the board? So it just creates a virtual "-". Are you planning to bypass this and connect your own dual voltage LPS or "-" voltage LPS to see if it helps on the noise/improves sound?

Btw what does the NRC abreviation mean?

I have also had good experience with the LM4562 from the IVY III BALANCED LINESTAGE from TPA

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yes, it seems to be the case by the look of it when I follow the traces...
Nope, just one 14V main LPS via 12pin connector and keep the rest as is, don’t expecting any improvement to the distortion/sound just the PSU noise/spikes you can see prior to main 1khz tone

by NRC I meant NJW1194 volume chip as identified on the first page

I had those in the buffer stage of class D amplifier and was very happy with them

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so, bc is soldered back and original SMPS connected, I did test the distortion with the linear lab PSU before and couldn't see any difference so SMPS stays, no point of spending more money on it if there's no benefit, tomorrow will put it all back into its original shape and I can say I'm done with it...

 

IMG_2924.thumb.JPG.eb3dd372d561799ea455bbf854d61ae9.JPG

 

did also final test with -10db signal which is still above of what music would normally represent and here's the result, all harmonics went down, third more than 20db, it's fair to say we shouldn't be too much worried about its distortion 

I would still recommend to stay away from spdif input and to stay below -2db on the dial due to sharp rise of distortion past this point, if anybody needs higher output (more volume) I would suggest more powerful amplifier instead

 

439633925_Arta1newULNregonanalogstagestreamingtestIVstageIIwithSMPS-10dbsignal.thumb.jpg.a312f505505ac648936a2eafaf9146a7.jpg

 

Howgh...

 

 

 

 

.

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12 hours ago, kukynas said:

so, bc is soldered back and original SMPS connected, I did test the distortion with the linear lab PSU before and couldn't see any difference so SMPS stays, no point of spending more money on it if there's no benefit, tomorrow will put it all back into its original shape and I can say I'm done with it...

 

IMG_2924.thumb.JPG.eb3dd372d561799ea455bbf854d61ae9.JPG

 

did also final test with -10db signal which is still above of what music would normally represent and here's the result, all harmonics went down, third more than 20db, it's fair to say we shouldn't be too much worried about its distortion 

I would still recommend to stay away from spdif input and to stay below -2db on the dial due to sharp rise of distortion past this point, if anybody needs higher output (more volume) I would suggest more powerful amplifier instead

 

439633925_Arta1newULNregonanalogstagestreamingtestIVstageIIwithSMPS-10dbsignal.thumb.jpg.a312f505505ac648936a2eafaf9146a7.jpg

 

Howgh...

 

 

 

 

.

Hi Dan,

 

Very strange that there aren't any improvement but thanks for a huge job.

I still think there could be some component blocking besides the NRJ for getting lower distotion and noise.

Did you keep the OPA1612 in?

Did you hear a difference when the LPS was in compared to you current setup?

Did you measure the PSU noise at the OPAs and clock and DAC?

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Hi,

potentially yes, I think those switching bc’s leaking some noise into the power rails / ground but without having a chance to change all of them it’s hard to judge, it’s multilayer board so impossible to trace and measure everything...

yes, OPAs1612 are there and I’ll keep them there...

didn’t hear any difference between lab psu and SMPS...

nope, dsp board has to be attached to be able to measure the DAC board power rails due to fact dsp board is controlling on/off state of the psu rails and I can’t get to the dac board as there’s not enough space to reliably measure surface parts without potentially shorting their pins, even if I could my scope does’t go below 20uV which is still more than what those uln regs are capable of + those opas have pretty high PSRR and CMRR so might not be relevant

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The tone control can be bypassed as  @kukynas has done before.

734130074_Tonecontr.JPG.9ec017d317e049f6807af57aca3fc4f8.JPG

and turning it off will have impact on the THD at least at the high frequencies. Howver the NJW1194 still is the biggest contributor to THD compared to the OPAs1121061725_THDtoneonandoff.JPG.7fbba5d94db17b0a1add214a78d16a0f.JPG

Even though you can set fixed volume on the C658 then it looks like it is just fixed within the NJW1194 and not bypassing it. See manual.

1351794083_fixedvol.JPG.5eae9a6d7c66d796cd9b12fcf4364c0a.JPG

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yep, can't bypass that volume chip 

btw. just in case someone would ask, all measurements done with streaming input were taken using wifi, I did test it with lan and as expected performance is the same  

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On 25/02/2021 at 7:33 PM, kukynas said:

so, bc is soldered back and original SMPS connected, I did test the distortion with the linear lab PSU before and couldn't see any difference so SMPS stays, no point of spending more money on it if there's no benefit, tomorrow will put it all back into its original shape and I can say I'm done with it...

 

IMG_2924.thumb.JPG.eb3dd372d561799ea455bbf854d61ae9.JPG

 

did also final test with -10db signal which is still above of what music would normally represent and here's the result, all harmonics went down, third more than 20db, it's fair to say we shouldn't be too much worried about its distortion 

I would still recommend to stay away from spdif input and to stay below -2db on the dial due to sharp rise of distortion past this point, if anybody needs higher output (more volume) I would suggest more powerful amplifier instead

 

439633925_Arta1newULNregonanalogstagestreamingtestIVstageIIwithSMPS-10dbsignal.thumb.jpg.a312f505505ac648936a2eafaf9146a7.jpg

 

Howgh...

 

 

 

 

.

Hi Dan,

Once again, thank you for the effort!
I'm sorry for being so slow - but I'm still trying to keep up with your testing and conclusions. 🙂

  1. Changing opamps yielded a decent reduction in distortion - but changing other components made little sense?
  2. The C 658 seems to distort with high input or output signal levels?
  3. Spdif input should be avoided?

As to issue #2 I'm trying to figure optimal volume settings, when using the C 658 as a streamer with fixed volume - and I'm a bit unclear about your last test with signal -10dB.
Did you reduce coax input volume on the C 658? Or just adjust the signal from PC/ADI to match "real-life" input levels?
(NAD seems to recommend fixed output at -20dB and input at 0dB)

Best regards

Martin

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Hi Martin

 

1. correct, most probably reg for oscillator as well but can't confirm due to fact I have no measurements before the change 

2. output levels

3. yes if possible, higher distortion and jitter 

 

basically I created test signal with -10db which I streamed into the C 658 via Blueos and captured its output via ADI/PC, I didn't use spdif since previous page

anything above -2db is fine so the rest depends on your amplifier gain and volume control

 

Regards

 

Dan

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21 minutes ago, kukynas said:

Hi Martin

 

1. correct, most probably reg for oscillator as well but can't confirm due to fact I have no measurements before the change 

2. output levels

3. yes if possible, higher distortion and jitter 

 

basically I created test signal with -10db which I streamed into the C 658 via Blueos and captured its output via ADI/PC, I didn't use spdif since previous page

anything above -2db is fine so the rest depends on your amplifier gain and volume control

 

Regards

 

Dan


Roger,

So if I stick with builtin streaming, keep tone control off and stay clear of -2dB output volume, then performance should still be decent? (At least with typical input levels of streamed music)

Best regards
Martin

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      Item: NAD Masters Series M10 BluOS Streaming Integrated Amplifier
      Location: Melbourne
      Price: $3200
      Item Condition: As New
      Reason for selling: I need the money
      Payment Method: Pickup - Cash, Paypal, COD Only, PayID
      Extra Info: 
      Reluctantly selling my  NAD Masters Series M10. I have had an unexpected financial situation arise and as a result I’ve listed my newly acquired piece of kit here. 
      This item is as new and never been used. Purchased in early May 2019 for $3949.  Only taken out of the box for the purposes of photographing for listing on the StereoNet clasifieds forum.
      The NAD Masters Series M10 has an RRP of $3999
       
      I would be open to reasonable offers and happy to freight anywhere in Australia. Cost of freight is not included in the asking price, but can be discussed pending sale.
       
      Reviewed by Mark Gusew in March 2019:  https://www.stereo.net.au/reviews/review-nad-m10-bluos-streaming-amplifier

       

      Photos: Advertisements without photos of the actual item will not be approved.





    • By BugPowderDust
      Item Condition: Very Good Shipping Options: Pickup available but audition is not available.,Shipping is available at agreed cost. Suburb or Town: Macedon Ranges, VIC or Melbourne CBD State: VIC Payment Method: Paypal, EFT, PAYID, Cash Reason for selling: Surplus to needs Further information:
      I've had this integrated gathering dust in my cupboard for too long, awaiting fitting out a cottage which is now connected to a Sonos sound bar.
       
      It's in great running order, no dings and scratches and sounded great on the pair of Paradigm Signature S1's I was running it with previously. Remote also included, barely used.
       
       
      More details here: http://www.audioreview.com/product/amplification/integrated-amplifiers/nad/c325bee.html
       
      Photos:

       
    • By NADCRUSHER
      Item Condition: USED - FAULTY Shipping Options: Pickup available but audition is not available.,Shipping is available at agreed cost. Suburb or Town: Woodend State: VIC Payment Method: EFT, cash on pickup Reason for selling: NLR Further information: Amp recently developed a fault - sounds okay up to 40 % volume, but when pushing any higher an awful distortion appears before the amp quickly cuts to protection mode. I decided to upgrade rather than repair. Could be an easy fix, could be fit for the bin. MT1 media module included. Local pickup preferred. 
       
      Photos:
       
      PLEASE READ
      If you include any reference to pricing whatsoever in this section (excluding RRP), your ad will not be approved If you are advertising multiple items, you must post one bulk price only, or post seperate ads for each item If you don't include photographs of the actual item being sold, your ad will not be approved You understand that a reasonable donation for selling fees is expected upon successful sale of your item
      - if you have previously sold items and not made a donation, your advertisement may not be approved.



    • By waterwombat
      Item Condition: Used, in good working condition Shipping Options: Pickup available but audition is not available.,Shipping is available at agreed cost. Suburb or Town: BRUNSWICK WEST State: VIC Payment Method: EFT or Cash on Pickup, Paypal at buyers expense Reason for selling: NLR Further information:
      Second iteration of this classic HI FI amp still a great amp with good phono stage.
      A few scratches on top.  
       
       
      Continuous power output [W]: 2 x 20 at 8 Ohm Frequency Response [Hz]: 20 - 20000 Preamplifier Section Input Impedance: 47 Kohm THD: <0.03% High Level Input Impedance: 40Kohm Controls: Volume, Balance, Trable, Bass, Input selector Phono preamp: YES Colour: Grey Height x Width x Depth [mm]: 80 x 420 x 250 Weight [kg]: 5  
      Photos:
       
      PLEASE READ
      If you include any reference to pricing whatsoever in this section (excluding RRP), your ad will not be approved If you are advertising multiple items, you must post one bulk price only, or post seperate ads for each item If you don't include photographs of the actual item being sold, your ad will not be approved You understand that a reasonable donation for selling fees is expected upon successful sale of your item




    • By hiphile
      Item Condition: Used - Excellent Condition Shipping Options: Pickup available but audition is not available.,Pickup available and you can audition. Suburb or Town: Oakleigh State: VIC Payment Method: EFT Reason for selling: Downsizing Further information:
       
      Selling my beloved NAD C320BEE Integrated Amp and C521BEE CD Player in excellent condition.
       
      Both have had very easy life and little use over the years - I listen to at most 1-2 hours per week and for the past few years, probably 1-2 hours per month.
       
      Both are in excellent condition with no dings / scratches. Remote is also in perfect working and excellent cosmetic condition.
       
      The CD laser is getting a little tired, befitting its age. It doesn't like dirty / old / scratched up discs. However you can get replacement ones on eBay for cheap if you wish. To be honest it still plays 90% of my CDs so I never bothered.
       
      Also includes high quality QED Qunex interconnect cables between CD player and amp (worth $100 new) and a Belkin 3.5mm to RCA to connect your portable device.
       
      Comes with 2 remotes, the fully featured SR 5 amp remote and the CD 6 CD player remote (never used).
       
      Comes with manual and the original brochure! 😀
       
      Selling due to downsizing and wishing to simplify with an all in one streamer / multi-room system.
       
      Pickup only due to bulk and I no longer have the boxes.
       
      Any questions please ask.
       
      Cheers
       
      Photos:


       
       
      PLEASE READ
      If you are advertising multiple items, you must post one bulk price only, or post seperate ads for each item If you include any reference to pricing whatsoever in this section (excluding RRP), your ad will not be approved If you don't include photographs of the actual item being sold, your ad will not be approved



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