Understanding Sample Rate

[jabbr]

9 hours ago, Em2016 said:

 

Any issues with increasing clock phase noise, as you go to DSD256 and then higher to DSD512?

 

I guess it depends on the clock used of course but do we know about clock phase noise performance of the iFi micro DACs? @jabbr 

 

I do agree DSD512 to the iDSD sounds nice though.. but are we liking something technically 'bad'? Nothing wrong with this of course.

 

 

I haven’t personally measured the iFi— so this is general — from the crystal/physics POV, the close-in phase noise increases as the frequency increases so, all else equal, an  11Mhz clock (DSD256) will have less phase error than a 22Mhz (DSD 512) clock.

 

However the DAC probably has one clock for each frequency family ie 44.1vs48 kHz so for a DSD256 input, the BCLK is generated by divide/2 and so the phase errors should be roughly similar module the error from division (should be small)

 

I agree that the analogue output stage is probably the weakest link.

[jabbr]

1 hour ago, Em2016 said:

Is there something/s they are measuring that others haven't/can't (access to better equipment)?

 

It’s a more complicated issue than me get first appear, and individuals have biases depending on their own implementations. 

 

Yes its true that all else equal slower clocks have lower close in phase error — however what the optimal DSD rate is for SQ is a much much more complicated question.

 

There is good reason to believe that DSD512 can be better than DSD256 — so at face value don’t believe that quad rate is necessarily optimal. In my experience certainly not DSD128!

 

DSD1024 has not been widely implemented so the optimal rate could be DSD512 or perhaps DSD1024 or somewhere in between. 

 

Now that means you need logic that can itself handle high frequencies with low phase error and this logic can be either expensive or custom and so expensive

[jabbr]

2 hours ago, crenca said:

 

Oh dear.  Is she playing the roll of Ted Denney or does she innocently believe such is the case?

I think it’s certainly possible that physical CD-R might sound different directly played. Barry Diament says the same. 

 

One should not make the serious mistake that such differences survive eg network transmission or are audible on all systems.

 

The belief that such SQ differences are somehow baked in is where lack of technical understanding can be harmful yet Cookie Marenco doesn’t say that and largely provides downloads these days. Her downloads are high quality  

 

You know, I think she is often quoted entirely out of context 

[jabbr]

4 hours ago, mansr said:

I won't say it's impossible, but it should be a rare exception. If the player has trouble tracking or maintaining focus, or if the error rate is abnormally high, it could maybe, possibly cause some noise on a poorly designed player. Any two spec-compliant discs played on decent gear should sound the same.

 

He says a lot of things.

 

Dont want to beat a dead horse too much but it was Gordon Rankin from whom I first heard the SQ advantage of ripping a CD to hard drive and subsequent playback. He has a rather good technical background. 

 

@alfe has his own views  

 

In in any case there are many people who have heard SQ differences between CD and hard drive, so CD to CD doesn’t seem too far a leap. 

 

I rip all my CD, DVD, SACD, blu Ray etc to harddrive so dont really think about this ??‍♂️

[jabbr]

13 hours ago, mansr said:

I have no respect whatsoever for Gordon Rankin. He is a liar and a jerk. He'll say whatever will sell his latest snake oil.

 

 

Oooohhh... You may have whatever opinion you have, and whether you have respect for him is your own decision, but this post is over the top and personal. There is no need to make personal attacks and does nothing to help your own position. Not that you care, apparently.

 

I have great respect for Gordon whether I agree with everything he says or not. There are many other engineers who I respect whether I agree with them or not. Gordon has clearly been involved in the creation and deployment of async USB at a very deep level and whether or not you like the protocol, it has become ubiquitous for USB DACs, and that alone is cause for great respect.

 

Gordon does more than software, firmware indeed he is very accomplished at hardware. He has licensed products and designs at various price points from a few hundred to many thousands of dollars, from ICs to vacuum tubes. From DACs to guitar amps.

 

Does he deserve to make a profit, and is he allowed to promote his latest design? Absolutely!

 

To call his stuff "snake oil" is totally unreasonable -- is Ayre "snake oil" also? 

 

Perhaps you are blinded by MQA but MQA is hardly what Gordon Rankin is about even if he wrote firmware supporting it.

 

13 hours ago, mansr said:

 

Comparing a CD to a rip involves completely different hardware. A slight difference isn't entirely implausible. Two good discs played on the same player really shouldn't sound different. If they do, I'd call the player defective.

 

Whatever. Your opinions are arbitrary and when you throw around unfounded insults, it calls into question every opinion you have. 

 

If you want to stick to math, then please stick to math. Again real engineers like @alfe who have designed and made CD can attest to the real differences between both players and physical discs. According your definition the world is defective.

[jabbr]

51 minutes ago, mansr said:

Go look at his tone towards me and others in the MQA on Dragonfly thread, then tell me he isn't a jerk. People have been banned for less. In the same thread, he also made various factually incorrect statements about his own design. If that doesn't make him a liar, I don't know what does.

 

No sorry (not going to read it). He likely was defending his product which you were likely attacking but less assume we are all adults and in my mind, a single heated thread does not make someone a jerk. Particularly if someone is defending his own work.

 

Making "factually incorrect" statements does not make someone a liar, particularly when you've made an above unqualified statement. At most you could say that someone "has lied about X" ... there is an important difference. Words matter.

 

Look, I'm no fan of MQA primarily because I detest closed formats. I've made my views known. You've done a great job debunking the technical claims of MQA. Really great job. So why not keep it technical? No reason to let technical arguments spill over into personal.

[jabbr]

Just now, Spacehound said:

"Alternative facts" perhaps?

Fair enough, but for example: https://www.quackwatch.org/01QuackeryRelatedTopics/pauling.html

 

The fact that Linus Pauling's statements about the merits of Vitamin C are called into question does not diminish the respect that should be accorded to him as a scientist.

 

Thats an example.

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43 minutes ago, Spacehound said:

My FTL spaceship is terrific. Only  a million dollars and seats two and a dog. Want one?

"Alternative facts" perhaps?

Is it a McLaren? Yes! Carbon fiber no less, and to keep on topic a Meridian soundsystem

 

[jabbr]

4 minutes ago, beerandmusic said:

Everyone knows that I don't agree that that 44.1K sampling rate can accurately capture all possible sounds up to 20Khz...so i am not sure what else is to discuss.  I don't even think that 44.1K sampling rate can capture all possible sounds between 100 and 101 hz.

 

This is flat out wrong and despite being told so, and provided literature and references, you maintain your fixed dogmatic yet incorrect viewpoint. 

[jabbr]

4 minutes ago, beerandmusic said:

 

I believe there are an infinite number of frequencies between 100hz and 101 hz, and the fact that the theorem has a criteria of bandlimited, that i don't believe the nyquist theorem can accurately capture all sounds between that range.

 

And like i said, it is possible i am incorrect...i just don't believe i am.

I don't know why people have such a hard time understanding that.

 

You can believe that 1 + 1 = 3 despite being told that it equals 2. I have a hard time why you refuse to either accept this or do some reading and work the math out for yourself.

 

Math and physics aren't like art. Not all opinions are equally valid.

[jabbr]

Just now, beerandmusic said:

You can't force someone to believe something.  They have to understand it. 

 

I can't force you to understand anything, but if you continue to say things in public that are blatantly and plainly wrong, I will note these so that other people don't being misinformed by your endlessly repetitive yet incorrect statements.

[jabbr]

41 minutes ago, beerandmusic said:

I don't really know the actual math, i just know that i can hear a lot more details in live than i have ever heard in recordings.

 

Right, so why conclude that because you can hear more details in a live concert than a recording that 1 + 1 = 3?

 

Why not question your assumptions? The math is correct. Why not question whether two channels bandwidth limited to 20 Khz can capture live? Why not question whether 16 bits can capture live? Why not question the microphones, the playback etc etc etc.... why question the math?

[jabbr]

As @mansr, says, the frequency quantization or time accuracy depends on the sample precision. The sample precision is limited by the baseline noise and can not be arbitrarily reduced by “better electronics” because the uncertainty principle determines the limit of our ability to reduce “noise”.

 

This is no real concern waveforms add in known ways. It all works!

[jabbr]

1 hour ago, Ralf11 said:

 

do we hit that limit in the real world?

 

I thought Johnson noise, etc. were the practical limits

 

At least “shot noise” is described as due to the quantum nature of electrons (https://arxiv.org/pdf/cond-mat/9407011v1.pdf) also 1/f noise (http://physics.princeton.edu/~mcdonald/examples/statistics/handel_pra_22_745_80.pdf)

[jabbr]

also: https://www.copilot.caltech.edu/documents/298-prd_caves_quantum_noise_limits_amplifier_1982.pdf

[jabbr]

3 hours ago, Ralf11 said:

 

do we hit that limit in the real world?

 

I thought Johnson noise, etc. were the practical limits

 

Ok, sitting down and a little more time to explain this -- I started this discussion way above with a casual reference to Einstein's Brownian Motion as being the limits of frequency resolution ...

 

Without delving too too deeply into the mathematical and quantum physics thickets here are a few references:

 

http://www.feynmanlectures.caltech.edu/I_41.html

https://arxiv.org/pdf/1009.0843.pdf

 

This discusses the quantum mechanical basis behind brownian motion.

 

Now the relationship between Brownian Motion and Johnson Noise:

http://aapt.scitation.org/doi/abs/10.1119/1.18210

http://123.physics.ucdavis.edu/johnson.html

http://www.damtp.cam.ac.uk/user/gold/pdfs/teaching/ufk_papers/optical_tweezers/gittes-schmidt.pdf

 

Essentially Brownian Motion in a gas/fluid is analogous to Johnson noise in a metal/semiconductor.

[jabbr]

5 hours ago, Ralf11 said:

 

 

Here is the crux of the bisquit:

 

"the low pass [filter] before the sampling stage has to be extremely sharp to avoid cutting any audible frequencies below 20kHz but still not allow frequencies above the Nyquist to leak forward into the sampling process. This is a difficult filter to build..."

 

I suspect that is what beer was hearing.

 

Or, as is what’s really done, record at 96-192 kHz and there won’t be signal which needs filtering or a more gentle filter can be employed.

[jabbr]

2 hours ago, adamdea said:

(In much the same way that the existence of DSD64 proves that nothing over 20 Khz matters.)

 

Huh? 

[jabbr]

4 minutes ago, adamdea said:

What happens to all that quantisation noise in the sub 20kHz range? Why is this acceptable?

Now I’m following your logic even less ...

 

Aside from reality, how would sub 20kHz noise prove or disprove anything about >20 kHz signal?

[jabbr]

4 minutes ago, adamdea said:

If we could actually hear over 20kHz what would this sound like?

That’s what you call a proof? Hmm ...

[jabbr]

5 minutes ago, adamdea said:

I'm talking about the quantisation noise that has to be shaped by the noise shaper. Sorry if that was not obvious. You have 1 bit of resolution spread over 64fs that still only 4 bits in the audioband isn't it. Where do we put the other 12 bits of noise to get 16 bit performance in the audioband?

http://bitperfectsound.blogspot.ca/2014/09/noise-shaping.html

 

I'll defer to @Miska who may have some nice graphs of the effects of his actual noise shaping as HQPlayer upsamples from DSD64 to DSD512 and the effects on this "quantisation noise" -- and I routinely upsample from both PCM and DSD source to DSD512 to feed into the iFi Micro, for example.

 

So your argument assumes a specific implementation which is, I'd say irrelevant and proves nothing.

 

Not a proof, not even close. Check your assumptions at the door. I am not saying that there is proof either that ultrasonics have an effect on SQ but according to your own logic, the fact that DSD256-DSD512 upsampling sounds better than DSD64 would be "proof" that ultrasonics matter? According to your logic, you could "prove" whatever you felt like on any day of the week.

[jabbr]

14 minutes ago, adamdea said:

but it is tricky to make a case for the region above 20Khz mattering if one is happy to pollute it too heavily.

But conversely if I or most people who listen to DSD are noise shaping this region above 20 kHz, and notice a preference when doing so,  then does that suggest the region is important?

 

How many people who use HQPlayer have a preference for DSD64 over DSD128? How many people feed DSD64 into an NOS DAC?

 

Your argument is spurious.