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Null test 88.2/24 and 44.1/16


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1 hour ago, pkane2001 said:

Here's what my own DeltaWave software as able to determine from about a 2.5 minutes extract from the middle of the recording.

 

The comparison is between the original 88.2Khz/24 bit recording and a downsampled version to 44.1Khz/16bit, then upsampled back to 88.2Khz/24 bit, as described by @bachish (thanks for the files!)

 

By the way, the recording sounds excellent! I also listened to the difference between the two files, which is primarily white noise. I was able to hear occasional notes come through buried in the noise, but only with software digital volume adjusted to about 70dB gain and my DAC set to 0dB (max volume).

 

The files were delivered with the upsampled version with inverted phase. Otherwise, the files match perfectly in level and phase, no phase offset or drift was found.

 

First, a comparison of the spectra of both waveforms. Original 88.2/24 is in blue:

 

image.thumb.png.13775eadc4a072b9cbbad47131105be6.png

 

The drop off do to downsampling/upsampling starts around 21800Hz at -92dB down. Here's the zoomed in portion where the cut-off starts. You can also see very tiny differences in level due to dither and computational error during resampling:

 

image.thumb.png.ae07d33c866488a256a0a6a4df1cd23a.png 

 

Now the actual waveforms overlaid on top each other:

 

image.thumb.png.1d267fca2e35d1f0360160160837aeb4.png

 

Stats below show excellent correlation between the two: 76dB correlated null and -75dB difference (rms).

 

Spectrum of the difference of the two files. Well below -115dB in the audible range:

image.thumb.png.e6d29c86a9040cad7b4572a1d2a97ce1.png

 

Spectrogram of the original 88.2/24 file:

image.thumb.png.c7427bca258964c7cf6828b07de551eb.png

 

And spectrogram of the downsampled/upsampled file:

image.thumb.png.ed0642a997f6523c701b117e0ff7324c.png

 

Spectrogram of the differences of the two files:

image.thumb.png.b3e006b88ca1daea9950489267d388d4.png

 

Interesting results in the cepstrum analysis of the two files:

 

image.thumb.png.9b40bc21674c10c90d957dd397038638.png

 

This shows that the downsampled/resampled file has some ringing/aliasing going on at a number of frequencies that are not present in the original 88.2/24 bit file. Probably the side-effect of the resampling process and filtering applied. I tried to label the main ones. Note that the vertical value (Y axis) is a correlation coefficient. It's an indication of how strong the ringing is in the measured file, while the X coordinate is the frequency at which this ringing was detected.

 

While the artifacts of the resampling process are visible in the Cepstrum plot, they are not at all noticeable in any of the measurements or in listening to the differences between the two files.

 

 

 

 

After I posted, I was looking again at your analysis and a couple questions occurred to me. 

 

In the Cepstrum plot, the y axis - I'm curious what measurement that is.  Just trying to get a handle on just how loud the ringing is. You mention the level is pretty low, I realize. 

 

In the 'Spectrum of the difference of the two files. Well below -115dB in the audible range' the left side of the graph looks like the noise shaping of the dither applied, which would make sense.  So essentially, that graph is showing that the difference between the two files is primarily in the dithering and the high frequency content from the original file. Am I reading that correctly?

 

Thanks!

 

 

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7 hours ago, bachish said:

My understanding is that -80db below the signal is considered inaudible and covered by the masking effect.

 

If you were trying to hear noise, that's correct. But we're trying to hear music. :) How much very low level musical detail is the noise masking?  (Maybe none, considering the noise level of a typical listening room, but it's the way of conceptualizing noise and masking that I'm thinking of.)

One never knows, do one? - Fats Waller

The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. - Einstein

Computer, Audirvana -> optical Ethernet to Fitlet3 -> Fibbr Alpha Optical USB -> iFi NEO iDSD DAC -> Apollon Audio 1ET400A Mini (Purifi based) -> Vandersteen 3A Signature.

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51 minutes ago, Jud said:

 

If you were trying to hear noise, that's correct. But we're trying to hear music. :) How much very low level musical detail is the noise masking?  (Maybe none, considering the noise level of a typical listening room, but it's the way of conceptualizing noise and masking that I'm thinking of.)

 

I turned up the volume 70dB in digital processing, and turned my DAC to 0dB setting to hear the difference file. You'd never listen to a recording like this! There is a lot of static noise with a few musical notes coming through, occasionally. So, yes, there's some information that's in the original file that's not in the resampled one, but it is at a level where it is completely buried by noise. 

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3 hours ago, Jud said:

 

If you were trying to hear noise, that's correct. But we're trying to hear music. :) How much very low level musical detail is the noise masking?  (Maybe none, considering the noise level of a typical listening room, but it's the way of conceptualizing noise and masking that I'm thinking of.)

I think when talking about noise in these files, we need to realize that -100db is the equivalent to 0.001 % distortion in audio equipment.  Highly unlikely we would hear this. 

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Interesting.  When the OP transmitted these files to Paul over the Internet, was the EM/RF "noise" of your computer, your ethernet cables and switches/routers, etc. taken into account?  Would "audiophile" networking equipment made any difference to any computational analysis?  What if you retransmitted these files several times and due to the differing paths these filed traveled over the Internet backbone (as any tracert will tell you), an analysis was done to see the effects these differing routes had?

 

Along these lines, what would happen if you took these files and transmitted them back and forth from your computer to an external HD connected via USB, say 1000, or 10,000, or 10,000,000 times?  How would this computational analysis be effected, and would it matter if your USB connections used "Audiophile" USB cables, USB decrapifiers, and differing USB design implementations?

Hey MQA, if it is not all $voodoo$, show us the math!

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21 hours ago, Jud said:

 

Right, just wanting us to remember that A/D is the flip side of what goes on in a DAC - first converted from analog to digital with sigma-delta modulation, then (with most ADCs) converted to PCM at 352.8 or internally/externally downsampled to the more common resolutions, 192 or 176.4kHz or below.  So even the "hi res original" from the studio is almost always downsampled.

 

Following up on this -

 

Here are some recordings available from NativeDSD, and you can filter your search to come up with only those albums/tracks available in DSD256: https://www.nativedsd.com/new_browse

 

@bachish, @pkane2001, I don't know whether you're able to do the same analysis with one of these tracks, but it would be interesting to see whether a recording that presumably had experienced less processing would show any greater difference to a 44.1kHz resolution downsampled file than the 88.2kHz original you used before.

One never knows, do one? - Fats Waller

The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. - Einstein

Computer, Audirvana -> optical Ethernet to Fitlet3 -> Fibbr Alpha Optical USB -> iFi NEO iDSD DAC -> Apollon Audio 1ET400A Mini (Purifi based) -> Vandersteen 3A Signature.

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@Jud, on the contrary very on topic.  As much as I appreciate what the OP, Paul, have done and your cogent suggested expansion, the fact is most of this analysis has been done before and is (largely) non-controversial and accepted.  In Audiophiledom however much is claimed about not only about the integrity of sampling/down-and-up conversations, etc. so much as how all this does not matter because it is over those (realtively) short USB connection (or ethernet, etc.) that all the Audiophile grade endpoints, USB cables, and internal EM/RF "noise" do their thang to the sound (positively or negatively).  Suddenly, in this last 10FT or so of digital (analogue of course at the physical layer) transmission the "sound" of various files/connection method suddenly bloom up, including for yourself with whatever cheap USB mod your using currently.  There is a rather large disconnect between your faith in your own experience and the faith you are putting in this topics computational analysis because the fact is these files suffered all sorts of EM, RF, poor cables, and other assaults that you claim you "hear" in the last 10ft....  

  

Hey MQA, if it is not all $voodoo$, show us the math!

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10 minutes ago, crenca said:

@Jud, on the contrary very on topic.  As much as I appreciate what the OP, Paul, have done and your cogent suggested expansion, the fact is most of this analysis has been done before and is (largely) non-controversial and accepted.  In Audiophiledom however much is claimed about not only about the integrity of sampling/down-and-up conversations, etc. so much as how all this does not matter because it is over those (realtively) short USB connection (or ethernet, etc.) that all the Audiophile grade endpoints, USB cables, and internal EM/RF "noise" do their thang to the sound (positively or negatively).  Suddenly, in this last 10FT or so of digital (analogue of course at the physical layer) the "sound" of various files/connection method suddenly bloom up, including for yourself with whatever cheap USB mod your using currently.  There is a rather large disconnect between your faith in your own experience and the faith you are putting in this topics computational analysis because the fact is these files suffered all sorts of EM, RF, poor cables, and other assaults that you claim you "hear" in the last 10ft....  

  

 

I don't care.  :) 

 

I'm just interested in the very nice analysis these two kind folks have done, and looking forward to anything further they're able to do along the same lines.  But to save these people the trouble, if you have got a link to the types of measurements they've done, comparing a DSD256 recording and a 44.1kHz downsampled version, that would be great.  If including DSD is a problem, there are the 2L comparison tracks that would enable comparative measurements of 352.8 and 44.1kHz files: http://www.2l.no/hires/index.html?

One never knows, do one? - Fats Waller

The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. - Einstein

Computer, Audirvana -> optical Ethernet to Fitlet3 -> Fibbr Alpha Optical USB -> iFi NEO iDSD DAC -> Apollon Audio 1ET400A Mini (Purifi based) -> Vandersteen 3A Signature.

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2 minutes ago, Jud said:

 

I don't care.  :) 

 

I'm just interested in the very nice analysis these two kind folks have done, and looking forward to anything further they're able to do along the same lines.  But to save these people the trouble, if you have got a link to the types of measurements they've done, comparing a DSD256 recording and a 44.1kHz downsampled version, that would be great.  If including DSD is a problem, there are the 2L comparison tracks that would enable comparative measurements of 352.8 and 44.1kHz files: http://www.2l.no/hires/index.html?

 

I care ?

 

Another thought:   during the recording, downloading, resampling, and analysis of these files on the OP's and Paul's computer(s), these files were transmitted back and forth from memory to HD(s) countless times.  Yet, no "audiophile" grade cables or decrapifiers were involved (unless the OP and Paul wan't to correct me about the internals of their computers).  The assault from the EM/RF inside these computers on the files in question can hardly be imagined. Clearly, their results are mere objectivist dreams...  ?

Hey MQA, if it is not all $voodoo$, show us the math!

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Just now, crenca said:

The assault from the EM/RF inside these computers on the files in question can hardly be imagined.

 

On the contrary, its analog is experienced in all the threads polluted by fruitless debates.  It would be so very nice to keep this thread free of that sort of thing.

One never knows, do one? - Fats Waller

The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. - Einstein

Computer, Audirvana -> optical Ethernet to Fitlet3 -> Fibbr Alpha Optical USB -> iFi NEO iDSD DAC -> Apollon Audio 1ET400A Mini (Purifi based) -> Vandersteen 3A Signature.

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6 minutes ago, Jud said:

 

On the contrary, its analog is experienced in all the threads polluted by fruitless debates.  It would be so very nice to keep this thread free of that sort of thing.

 

Pot, black, etc. from you especially.  The OP can speak to rather he would like to discuss the "final 10ft" to DAC and is the usual audiophile claim that it is here (in this final 10 ft) that the differences between files suddenly become audible and obvious, at least to "audiophiles"...

Hey MQA, if it is not all $voodoo$, show us the math!

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3 hours ago, crenca said:

 

I care ?

 

Another thought:   during the recording, downloading, resampling, and analysis of these files on the OP's and Paul's computer(s), these files were transmitted back and forth from memory to HD(s) countless times.  Yet, no "audiophile" grade cables or decrapifiers were involved (unless the OP and Paul wan't to correct me about the internals of their computers).  The assault from the EM/RF inside these computers on the files in question can hardly be imagined. Clearly, their results are mere objectivist dreams...  ?

My knowledge is very limited but from what I have read the problem is not when transferring the digital data around but in the data stream which leaves the music playing/processing software to the DAC.

If this is correct, what are the differences between moving data around and that stream which is fed to the DAC?

"Science draws the wave, poetry fills it with water" Teixeira de Pascoaes

 

HQPlayer Desktop / Mac mini → Intona 7054 → RME ADI-2 DAC FS (DSD256)

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8 hours ago, pkane2001 said:

 

Cepstrum attempts to find repeating patterns in the frequency domain. The Y axis in the plot is a correlation coefficient. All it's saying is that a relatively higher value has a relatively greater amount of ringing (i.e., the pattern is better defined). It doesn't say anything about the level of ringing.  Since it does point to specific frequencies, it might be interesting to see if the magnitude can somehow be dug up from the signal and noise in the frequency domain. Not sure that's possible, but I'll think about it some more :)

 

 

Right. Most of the differences are well below -115dB in the frequency domain. But, that represents an average over the measured period. For a time version of the difference plot, here is what it looks like in the time domain:

 

image.thumb.png.4e47cb5f3a0be4754592c21ce68aadfd.png

 

You can see some peaks rising to about 0.02. In dB terms, that represents about -34dB level. But that's just a few peaks. Most of the difference is well below -100dB level. By the way, this is the waveform I listened to to hear the difference. Most of it sounds like noise, with a few very occasional notes coming through. Probably corresponding to some of the peaks in the above plot. So, there is some difference between the files, they are not a perfect match, but they are very, very close.

 

Here's that same difference plot but with all the frequencies above 20KHz removed:

image.thumb.png.8d1b09b2c281a7b0cd5f1aafe5dc566a.png

OK, thank you for the more detailed information. It would  be interesting to fine tune the conversion settings to see if those larger spikes couldn't be tamed. 

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3 hours ago, Jud said:

 

Following up on this -

 

Here are some recordings available from NativeDSD, and you can filter your search to come up with only those albums/tracks available in DSD256: https://www.nativedsd.com/new_browse

 

@bachish, @pkane2001, I don't know whether you're able to do the same analysis with one of these tracks, but it would be interesting to see whether a recording that presumably had experienced less processing would show any greater difference to a 44.1kHz resolution downsampled file than the 88.2kHz original you used before.

 

Sorry, Jud, no DSD support in DeltaWave :) It took me a while to code WAV and FLAC file support, until I found a library that could do it all for me. No DSD support, so it would have to be converted to PCM before I can process it and that would probably negate any analysis of the very low level details. Why do you think that DSD captures would be subject to less processing than PCM that @bachish captured and processed himself?

 

 

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4 hours ago, crenca said:

Interesting.  When the OP transmitted these files to Paul over the Internet, was the EM/RF "noise" of your computer, your ethernet cables and switches/routers, etc. taken into account?  Would "audiophile" networking equipment made any difference to any computational analysis? 

 

@crenca, I didn't realize your name was Alex??? O.o

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4 hours ago, crenca said:

Interesting.  When the OP transmitted these files to Paul over the Internet, was the EM/RF "noise" of your computer, your ethernet cables and switches/routers, etc. taken into account?  Would "audiophile" networking equipment made any difference to any computational analysis?  What if you retransmitted these files several times and due to the differing paths these filed traveled over the Internet backbone (as any tracert will tell you), an analysis was done to see the effects these differing routes had?

 

Along these lines, what would happen if you took these files and transmitted them back and forth from your computer to an external HD connected via USB, say 1000, or 10,000, or 10,000,000 times?  How would this computational analysis be effected, and would it matter if your USB connections used "Audiophile" USB cables, USB decrapifiers, and differing USB design implementations?

I have to admit, you did make me chuckle. Point well made, though, in a somewhat smart @$$ way. Haha

 

 

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14 minutes ago, pkane2001 said:

Sorry, Jud, no DSD support in DeltaWave :) It took me a while to code WAV and FLAC file support, until I found a library that could do it all for me. No DSD support, so it would have to be converted to PCM before I can process it and that would probably negate any analysis of the very low level details.

Shouldn't be difficult to add DSD support. What library are you using? Libsndfile or something else? This is off-topic here, but feel free to contact me by PM or email if you'd like to discuss it further.

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4 hours ago, Jud said:

 

Following up on this -

 

Here are some recordings available from NativeDSD, and you can filter your search to come up with only those albums/tracks available in DSD256: https://www.nativedsd.com/new_browse

 

@bachish, @pkane2001, I don't know whether you're able to do the same analysis with one of these tracks, but it would be interesting to see whether a recording that presumably had experienced less processing would show any greater difference to a 44.1kHz resolution downsampled file than the 88.2kHz original you used before.

 

It would be interesting to try it with DSD. DSDis a different way to capture the analog signal (super high sample rates at 1 bit) so the math would be different. 

 

My understanding is that, unlike the past, editing can be done in DSD without converting it to PCM. 

 

Unfortunately, I dont have any DSD software. Otherwise, I would be curious to at least try a null test.

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4 hours ago, Jud said:

 

I don't care.  :) 

 

I'm just interested in the very nice analysis these two kind folks have done, and looking forward to anything further they're able to do along the same lines.  But to save these people the trouble, if you have got a link to the types of measurements they've done, comparing a DSD256 recording and a 44.1kHz downsampled version, that would be great.  If including DSD is a problem, there are the 2L comparison tracks that would enable comparative measurements of 352.8 and 44.1kHz files: http://www.2l.no/hires/index.html?

 

Thank you, Jud! Interesting. I'll have to check these out. Thanks. 

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39 minutes ago, pkane2001 said:

Why do you think that DSD captures would be subject to less processing than PCM that @bachish captured and processed himself?

 

Hi Paul -

 

I was thinking to capture the recording at an earlier stage of the A/D process.  The way I understand the files from NativeDSD originate and are edited  (@bmoura and @tailspn will know more), during editing either only the portions being edited or the entire file would be converted from sigma-delta modulated format to PCM for some operations, then the relevant portions or the entire file would be converted with a modulator to DSD256 format, and no additional conversions/decimation would have been done.  Or with the 2L files, the "DXD" (352.8kHz) files would have come from the ADC already converted in their entirety to PCM, edited in that format, and no further conversions/decimation done from there.  This would be in contrast to an 88.2kHz file, which I believe would have to be decimated from some higher PCM resolution.

 

If all this is correct (and I'm not certain it is), then I'd be interested to know whether there's much (if any) more difference between one of these files and a 44.1kHz version, versus the 88.2kHz/44.1kHz comparison.

One never knows, do one? - Fats Waller

The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. - Einstein

Computer, Audirvana -> optical Ethernet to Fitlet3 -> Fibbr Alpha Optical USB -> iFi NEO iDSD DAC -> Apollon Audio 1ET400A Mini (Purifi based) -> Vandersteen 3A Signature.

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