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Article: Digital Vinyl: Temporal Domain


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Here is something with an impulse. First signal at the top is single sample pulse at 176.4 khz. The right channel is one sample off from the left. This is 1/4 sample at 44.1 khz.

 

Next is the same signal at 44.1 khz. You see the same sample peaks in each channel. Yet the size of the peaks is different and the sample values around the peak in the right channel are different. This will cause the same waveform to be constructed in each channel, but one shifted in time for the right channel as that is what will fit the different sample values.

 

Finally the 44.1 khz signal at 176.4 khz again. I did amplify this some 17 db as energy in the peak that was above the cutoff frequency was lost when done at 44 khz. While rounded due to bandwidth limiting you see the the peak value in the right channel is offset exactly one sample vs the left channel. Indicating it maintained the timing between these two impulsive signals. The rounding and loss of energy would have been experienced by your ears as they too are bandwidth limited to 20 khz or less.

 

impulse 176 vs 44.png

 

Sample values for the 44.1 khz file around the impulse.

 

time shift impulse.txt 2 channels (stereo)

Left channel then Right channel on same line.

Sample Rate: 44100 Hz. Sample values on dB scale.

Length processed: 14 samples 0.00032 seconds.

 

 

-30.34363 -28.46066

-29.90276 -26.91358

-29.53629 -25.27739

-29.23927 -23.42638

-29.01110 -21.12436

-28.84828 -17.79784

-28.75200 -11.27666

-2.02987 -2.86174

-28.75200 -18.34301

-28.84828 -25.48005

-29.01110 -31.55778

-29.23927 -38.49449

-29.53629 -51.19107

-29.90276 -49.25235

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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"Can you give an example of a signal condition which has no content above 20 khz, and yet is not resolved between samples at the sample rate of 44.1 khz?"

 

 

.... not likely.

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This thread has cleared up my misconceptions on the accuracy achievable with normal sampling methods, and I thank Jud, esldude and others for taking the time. I am now left pondering why MQA use a different sampling method. From their wiki page:-

 

"One more difference to standard formats is the sampling process. The audio stream is sampled and convolved with a triangle function, and interpolated later during playback. The techniques employed, including the sampling of signals with a finite rate of innovation, were developed by a number of researchers over the preceding decade, including Pier Luigi Dragotti and others."

 

Does anyone have an explanation ( none cynical please)?

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This thread has cleared up my misconceptions on the accuracy achievable with normal sampling methods, and I thank Jud, esldude and others for taking the time. I am now left pondering why MQA use a different sampling method. From their wiki page:-

 

"One more difference to standard formats is the sampling process. The audio stream is sampled and convolved with a triangle function, and interpolated later during playback. The techniques employed, including the sampling of signals with a finite rate of innovation, were developed by a number of researchers over the preceding decade, including Pier Luigi Dragotti and others."

 

Does anyone have an explanation ( none cynical please)?

 

The only explanations I can think of are cynical. Sorry.

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This thread has cleared up my misconceptions on the accuracy achievable with normal sampling methods, and I thank Jud, esldude and others for taking the time. I am now left pondering why MQA use a different sampling method. From their wiki page:-

 

"One more difference to standard formats is the sampling process. The audio stream is sampled and convolved with a triangle function, and interpolated later during playback. The techniques employed, including the sampling of signals with a finite rate of innovation, were developed by a number of researchers over the preceding decade, including Pier Luigi Dragotti and others."

 

Does anyone have an explanation ( none cynical please)?

 

It actually is not a "different" sampling method than anyone else has used. Filters are constructed by convolving a filter "kernel" with a function, such as (classically) a sinc function. MQA uses one of the available kernel choices, a triangular kernel.

 

Miska describes a triangular kernel in technical terms as "crappy." :)

 

 

Sent from my iPhone using Computer Audiophile

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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The argument Pure Vinyl seems to be trying to make here is that there can be two different 10kHz waveforms, where additional "precision" is required to reconstruct the two different, but same kHz tone waves. This has always struck me as the "my bass drum has an attack shape in its waveform that exists at 50Hz that makes it sound different than other 50kHz notes. Isn't the real science that my 50Hz bass drum wave is accompanied by higher spectral content, i.e. at 10kHz and 30kHz that further informs the sound and you need to preserve all of the content in order to capture the original sound?

Hi, sdolezalek

 

It doesn't affect the precision at all. Or any other *individual* frequency (taken by itself) that can be reproduced with that sample rate.

 

What is important is that the time relationships *between* different frequencies is better preserved by using a higher sample rate. But not the precision of reproducing any single frequency.

 

And yes, by the way, I, too, I can not hear 16kHz

Pure Vinyl Club

 

Listen to short demos of the LP Records

and share your experience and observations.

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Easily confused, yes. That's why it is a common misconception. You are still making the same mistake in thinking that digital sampling resolution is limited to the time between samples.

 

This is an unfortunate choice of analogy. It argues for accuracy / resolution in amplitude, not time, which is also an area where digital has a large superiority in resolution over vinyl.

 

Here you repeat your misunderstanding. You say that an event that occurs between sample times can only be captured to a time matching the closest sample time. This is incorrect. It is captured accurately, to the resolution defined by the equation in my earlier post. Your continued failure to understand how this can be so shows you lack the "training and experience on the subject" you talked of above. Have you watched the video I posted the link to? Starting from about 17:20 it shows, in real life, with a cheap DAC at 16/44.1, a transient being accurately sampled in time between sample times.

 

Here you display a lack of understanding of digital oscillosopes and how they are used. The biggest difference is that they do not depend on being able to sample at twice the rate of the highest frequency being measured. It's quite common to use such a scope in an undersampled mode. But for our purposes (audio), we stick to the classic Shannon-Nyquist model.

 

Make up your mind. Either digital can resolve transients in between samples, or it can't.

 

In the rest of your post, all you have done is make the case that 16/44.1 is marginal (but close enough for rock'n'roll), and that 24/96 is enough to capture everything that might possibly be significant.

 

 

As long as there's nothing in the signal you're sampling above 48KHz.

 

 

Wonder how much of the response from vinyl above 20KHz is truly signal as opposed to noise.

 

 

Sent from my iPhone using Computer Audiophile

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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By the way: None of what's been said should obscure the fact that while CD is capable of greater dynamic range than vinyl, CDs are all too often actually produced with a squashed dynamic range. No hocus pocus is necessary to explain this, only production decisions.

 

 

Sent from my iPhone using Computer Audiophile

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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It doesn't affect the precision at all. Or any other *individual* frequency (taken by itself) that can be reproduced with that sample rate.

 

What is important is that the time relationships *between* different frequencies is better preserved by using a higher sample rate. But not the precision of reproducing any single frequency.

 

That makes no sense at all.

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Here is something with an impulse.

 

And for those unconvinced by numerical calculations, let's fire up the scope again.

 

This is a single-sample impulse at 44.1 kHz with the right channel delayed one sample:

 

tek00000.png

 

As expected, we get the familiar sinc response with an offset of 23 μs.

 

Next, we keep the left channel unchanged while replacing the right channel with the sinc function evaluated at half-sample positions:

 

tek00001.png

 

Same response, but now with half the delay between channels.

 

Now a quarter sample delay:

 

tek00002.png

 

Again, the delay is reduced as it should.

 

Finally, a delay of 1/100th of a sample period:

 

tek00003.png

 

Still the expected result.

 

Recall that an impulse contains all frequencies up to the Nyquist limit. Since the response can be shifted by a tiny fraction of a sample period, the timing (phase) of every frequency must be accurately represented. In other words, there is nothing special about pure sine tones as has been suggested by some.

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By the way: None of what's been said should obscure the fact that while CD is capable of greater dynamic range than vinyl, CDs are all too often actually produced with a squashed dynamic range. No hocus pocus is necessary to explain this, only production decisions.

"The first cartridge with integrated RF shielding, the Clearaudio Goldfinger Statement MC phono cartridge is designed to play on the world's finest analog systems and reproduce the music on the greatest recordings ever made with unstinting clarity, liveliness, dynamics, realism, and responsiveness. Featuring 12 perfectly matched and symmetrical magnets – an unprecedented achievement – surrounding its coils. The Product of the Year Award-winning Goldfinger Statement allows systems to reach the long-unattainable dynamic range of 100dB." https://www.musicdirect.com/store/clearaudio-goldfinger-statement-mc-cartridge

Pure Vinyl Club

 

Listen to short demos of the LP Records

and share your experience and observations.

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As long as there's nothing in the signal you're sampling above 48KHz.

 

 

Wonder how much of the response from vinyl above 20KHz is truly signal as opposed to noise.

 

 

Sent from my iPhone using Computer Audiophile

 

Well that is the other part. I have taken some of the downloads offered, steep filtered everything below 20 khz, then slowed it down to 25% normal speed so I could hear ultrasonics. There is very little up there. It is mostly surface noise and widely spaced bits of cymbals at low levels.

 

It has been mentioned there is a slow roll off past 50 khz. Well not usually. 99% of LPs prior to digital were sourced from analog tape. Such tape isn't flat to 50 khz. Such tape also has scrape and flutter to effect timing. It certainly doesn't have infinite temporal resolution. It some situations the altered phase of high frequencies as the tape heads roll off could interact with drum-shots to cause something like pre-ringing at a lower frequency. Only unlike digital filter ringing it is well in the audible band. It is one of the DSP effects of DAW plug-ins to give a tape-like sound.

 

Then there is the IMD effects of higher frequencies interacting with the high frequency tape bias.

 

 

The reel project – part 3

 

You can read about a few such effects here.

 

Print thru anyone? That is another real effect of reel tape which will get put onto the LP. Sound like superb temporal performance?

 

Hey liking tape is all well and good. Ditto for LP. We need to get past this idea these prior mediums are superior to digital as they aren't.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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"The first cartridge with integrated RF shielding, the Clearaudio Goldfinger Statement MC phono cartridge is designed to play on the world's finest analog systems and reproduce the music on the greatest recordings ever made with unstinting clarity, liveliness, dynamics, realism, and responsiveness. Featuring 12 perfectly matched and symmetrical magnets – an unprecedented achievement – surrounding its coils. The Product of the Year Award-winning Goldfinger Statement allows systems to reach the long-unattainable dynamic range of 100dB." https://www.musicdirect.com/store/clearaudio-goldfinger-statement-mc-cartridge

 

 

Said like someone who doesn't understand how to read an FFT. The graphs were done with a 256 k FFT. Such a graph would have the noise floor near -150 db for a noise level across the full band of -100db. The graph shown for the cartridge in fact would be a dynamic range as such is usually determined of maybe 60 db give or take a bit.

 

Here is a better view of that graph down this page.

 

graph3.gif

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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Seems the aether ate one of my posts.

 

About the cartridge with 100 db dynamic range. Well no.

 

The graph is using a 256k FFT. At -100 db noise floor across the 20 khz bandwidth you would see a line of noise near -150 db on such an FFT. So I would guess maybe that cartridge has maybe 60-65 db dynamic range. It really would be nice to quit trying to mislead analog fans about "blowing CD out of the water". Just say you prefer the sound of LP.

 

A better picture of the graph on this page.

 

http://www.6moons.com/audioreviews/clearaudio3/graph3.gif

 

6moons audio reviews: Clearaudio Goldfinger

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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... 24/96 is enough to capture everything that might possibly be significant.

 

As long as there's nothing in the signal you're sampling above 48KHz. ...

 

Did you mean "nothing significant"? I left "for audio" off the end of my sentence. :-)

"People hear what they see." - Doris Day

The forum would be a much better place if everyone were less convinced of how right they were.

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Said like someone who doesn't understand how to read an FFT. The graphs were done with a 256 k FFT. Such a graph would have the noise floor near -150 db for a noise level across the full band of -100db. The graph shown for the cartridge in fact would be a dynamic range as such is usually determined of maybe 60 db give or take a bit.

 

Here is a better view of that graph down this page.

 

[ATTACH=CONFIG]33713[/ATTACH]

 

Then there is the RIAA curve vs. wow, and surface noise to consider, though surface noise can be "listened through." (The RIAA curve refers to low frequencies being diminished and high frequencies being boosted when a record is cut, and the reverse happening in the phono preamp at playback, to allow maximum playing time for a 33 /13 LP and minimize groove damage. The low frequency boost on playback is approximately 10db at the frequency - 400 Hz - where wow's perceived pitch distortions are centered.)

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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... Amen to that.

You know something's wrong when a metal album ends up less compressed than a semi-acoustic soul/blues album. (Iron Maiden, "The Final Frontier" versus Tom Jones, "Praise And Blame". Both mastered in 2010 by the same engineer.)

"People hear what they see." - Doris Day

The forum would be a much better place if everyone were less convinced of how right they were.

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[/font]

 

Did you mean "nothing significant"? I left "for audio" off the end of my sentence. :-)

 

 

 

Yep. Thinking of harmonics for trumpet, and some percussion. (Cymbals can have 40% of their energy above 20kHz.)

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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You know something's wrong when a metal album ends up less compressed than a semi-acoustic soul/blues album. (Iron Maiden, "The Final Frontier" versus Tom Jones, "Praise And Blame". Both mastered in 2010 by the same engineer.)

You got it!

 

The audiophile community IMO needs to be more focused on how the bits are MADE than squabbling how they get distributed.

Co-Founder/Chief Editor

http://www.metal-fi.com

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Well that is the other part. I have taken some of the downloads offered, steep filtered everything below 20 khz, then slowed it down to 25% normal speed so I could hear ultrasonics. There is very little up there. It is mostly surface noise and widely spaced bits of cymbals at low levels.

 

It has been mentioned there is a slow roll off past 50 khz. Well not usually. 99% of LPs prior to digital were sourced from analog tape. Such tape isn't flat to 50 khz. Such tape also has scrape and flutter to effect timing. It certainly doesn't have infinite temporal resolution. It some situations the altered phase of high frequencies as the tape heads roll off could interact with drum-shots to cause something like pre-ringing at a lower frequency. Only unlike digital filter ringing it is well in the audible band. It is one of the DSP effects of DAW plug-ins to give a tape-like sound.

 

Then there is the IMD effects of higher frequencies interacting with the high frequency tape bias.

 

 

The reel project – part 3

 

You can read about a few such effects here.

 

Print thru anyone? That is another real effect of reel tape which will get put onto the LP. Sound like superb temporal performance?

 

Hey liking tape is all well and good. Ditto for LP. We need to get past this idea these prior mediums are superior to digital as they aren't.

So is 16/44 enough to capture all the music in your opinion? And if so why do the majority of CD's of analog recordings sound crap compared to the analog version? Cheers!

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So is 16/44 enough to capture all the music in your opinion? And if so why do the majority of CD's of analog recordings sound crap compared to the analog version? Cheers!

 

16/44 or very little more than that can capture all of the music imo.

 

As for analog recordings vs digital ones there are multitude of factors. One inescapable factor is that LP even at it finest is not of full fidelity and has coloration. Maybe you like that coloration, maybe most do. That is okay.

 

So many factors. Are the masters the same? Did they try and squeeze more out of the CD because they could? Do the majority of CDs sound like crap vs LP (not in my experience) as some do and some don't? If you love LP have you tailored your gear for best sound on LP which works against CD sounding its best?

 

My basic thought is your premise of the question isn't true a majority of the time. It isn't generally true that CDs of analog recordings sound like crap. For one thing I have digitally recorded both reel tape and LP with the result sounding like reel tape or LP. So the digital CD isn't a bottleneck.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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So is 16/44 enough to capture all the music in your opinion? And if so why do the majority of CD's of analog recordings sound crap compared to the analog version? Cheers!

 

All the music that matters, yes. And they don't have to "sound crap", but:

 

- I spent a lot of time and money back in the 80s and 90s duplicating my LP collection in CDs.

- The majority of the CDs sounded similar to the LPs. Actually, they did sound different, but it was always the same difference, so I could blame the differences on my gear rather than something fundamentally wrong. I found I preferred the CD sound, and over time stopped listening to the LPs.

- I have since repurchased some of those CDs as remasters or re-releases. The majority of them do "sound crap" compared to the early versions. Even where they have been redigitised from the original tapes, in many cases the age of the tape is showing and/or the result has been compressed to modern levels.

- It is my belief that, in the majority of cases, a well cared for LP on a good turntable can be digitised to 24/96 then downsampled to 16/44.1 and the result will be so close to the LP as to not matter. If you're really fussy, leave it at 24/96.

"People hear what they see." - Doris Day

The forum would be a much better place if everyone were less convinced of how right they were.

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