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Will digital CD audio differ from player to player? (1 Viewer)

TimTurtino

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I just don't understand why you think I am not getting it. I have given references from JVC, one of the leaders is disc replication, that specifically talks to jitter in the disc replication process, I have given links to articles on Bob Katz website where he discusses jitter in the glass mastering process...
Well, that's a great example. Because using a text that is a "corporate white papers about corporate products aimed at audiophiles--such as the JVC document--does not qualify as science" (thanks, Jun-Dai).

Colin Powell is another great example-- to paraphrase the French Ambassador, Colin Powell left us some enticing clues-- he did not give us evidence. That certainly seems to be the most optimistic way to view what you've been doing...

Also, the arguments you're making in that last post (but one) are all essentially "appeals to authority". This is a simple logical fallacy, and it's not convincing. I'm sorry, but if the reasons I'm supposed to believe this basically come down to "some people (who may be on some web site, or somewhere else) on some web site all seem to believe it", then I'm going to believe the opposite until proven otherwise.

:)

Incidentally, speaking from a purely mathematical point of view, it's provable that, assuming some quite reasonable assumptions about sound waves (i.e., that it's impossible for a complete vauum to be created, that pressure differentials are all below a certain amount, etc), the maximum amount of error that can be introduced by sampling at different times is linearly related to the average time between samples, and the constant of porportionality can be kept quite small if reasonable signal processing is done.

But appeals to the fundamental theorem of calculus are going to be, I suspect, useless in a situation where nobody knows how to conduct a double blind test, or thinks that they have done one when they've flipped back and forth between two sources on their receiver.

Me
 

Lee Scoggins

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Colin Powell is another great example-- to paraphrase the French Ambassador, Colin Powell left us some enticing clues-- he did not give us evidence.
:rolleyes:I guess this shows forum what I am up against.

As Dennis Miller quiped recently, the only way to get the French involved is to say that truffles have been discovered in Iraq.

:D
 

TimTurtino

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1. No problem. Do you want me to do this at a level suitable for a bright undergraduate taking their first calculus course? Or should I do it at a level commensurate with a graduate student taking real analysis? The second will take longer (about 50 pages), but the only assumptions I'll make are things like
A) for three real numbers a,b,c > 0, if a>b, then ac > bc.
B) for any two real numbers a,b, there exists another real number between them.

(The list of axioms will be about 20 axioms long, but they will all be equally obvious)

The first method will be much shorter (around 4 pages), but will make use of many other results from basic algebra and geometry classes.

2. Your statement is true, if somewhat fatuous, because a given mathematical model of a situation rarely perfectly corresponds to a real situation. However, if one demonstrates that a given error was smaller than certain bounds (for instance, smaller than the error introduced by normal thermal patterns and air currents in a room), it would become most unreasonable to believe people could hear it.

Your unwavering insistence that recording jitter is a huge problem, in the face of the (never even argued with, let alone refuted) multiple arguments that jitter on the playback end has a much larger effect (incidentally, I don't know if this is true, since I've never measured either, although it certainly seems reasonable to assume that consumers use worse stuff than the pros do), makes me doubt that your opinion is grounded in any measurable or reproducible science, and why I highly doubt that a rigorous proof of a simple corollary to the fundamental theorem of calculus is actually going to do any good.

Last, the second to last of your posts is an example of the logic fallacy known as an "ad hominem" attack-- you are attacking the French as a people rather than the actual argument made by one particular French person. I (an American who is not in any way afraid or reluctant to go to war when I think it's justified and necessary) found Gen. Powell's statements to be, at best, clues to where a dedicated person with top secret clearance in this country might find actual evidence. By analogy, I find your statements to be, optimistically viewed, clues as to where a highly trained person might find sources of error in the CD playback process. However, neither were evidence in any sort of rigorous or meaningful way.

FWIW, Lee, I do appreciate your contributions to this Forum. For instance, I believe it was you who wrote up the documents on Hi-Res audio. I do not mean any of my arguments with your stated positions to be personal attacks on you or yours, and I hope they are not being perceived that way.

Me
 

John Royster

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Well if you can differentiate between transports then great!

If you can't, don't, or simply won't believe it then thats great too! Because we all just know that everything audio sounds the same in a DBT. This is not meant to offend, but simply realize that many people do hear changes in transports as realized by the original poster.
 

TimTurtino

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Not everything sounds the same in a DBT. It's _easy_, for instance, to tell the difference between a shelf system and a real stereo. Between stereo and surround sound. Between simulated surround and real surround. Between 10 wpc and 200 wpc.

And lots of other things that aren't nearly so extreme. It's only down at the other extreme that DBTs start to show no differences...

Me
 

Lee Scoggins

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Your unwavering insistence that recording jitter is a huge problem
Just to be clear, I am also saying playback jitter is a big problem as well. That has been much of the discussion as well. The earlier response about recording and playback was to a specific comment by Jagan wondering how we could handle the wow and flutter of analog tape during the creation. This stays constant for both machines.
 

Justin Lane

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Fourth, it is self-evident that my responses indicate that the presence of glass mastering jitter is such a problem that it is affecting album releases and leading Sony to develop new manufacturing processes.
Lee,

But aren't all the sources you just quoted coming from individuals or companies who want to sell anti-jitter equipment or services? You posted yourself that for $100,000, Sony's device can be retrofitted onto an existing glass mastering system. This is a quite biased and profit driven example in my opinion.

I generally try to stay out of these jitter debates because there is so much misinformation and no one ever changes their opinion regardless of the facts presented. Bottom line is I could care less how others spend their money. When it comes to CD players, you run into deminishing returns very quickly in my opinion. On the long check list of options and features found on a particular CD player, jitter induced by the player should be the last item you check off at this point in the technology.

J
 

Lee Scoggins

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You posted yourself that for $100,000, Sony's device can be retrofitted onto an existing glass mastering system. This is a quite biased and profit driven example in my opinion.
And they have sold a few of these! It think it strains credulity to suggest that a disc replication plant would spring for such a major investment if they did not think it would make a difference. Many high end manufacturers believe that the reason the JVC XRCDs are so sonically awesome is because of the jitter control on the mfg side as well as the during the mastering part.
 

Lee Scoggins

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Here is an excellent and free paper on Jitter Theory from the Audio Precision website:

http://audioprecision.com/publicatio...otes/index.htm

(register and download #23 - Jitter Theory, an excellent overview)

In the latter pages, there is a paper referenced that suggests the limit of audibility is around 10 nanoseconds for 17khz tone. The author cautions that recent work extends this lower limit even further.

I am attempting to get more recent research but at least we have some academic theory and research for jitter audibility that is completely unrelated to product sales.

The most recent AES discussion I attended suggested that 10-20 picoseconds is current limit.
 

Ian Montgomerie

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A lot of research is left to be done; one of the difficulties is finding measurement instruments capable of quantifying very low amounts of jitter. Until we are able to correlate jitter measurements against audibility, the ear remains the final judge. Yet another obstacle to good "anti-jitter" engineering design is engineers who don't (or won't) listen. The proof is there before your ears!
Hah! In other words, "we think we hear something but we can't demonstrate that objectively... darn those engineers who want an actual technical demonstration rather than our suvjective say-so".
 

Ian Montgomerie

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Here is some more discussion about music industry problems that were caused by glass mastering issues, from ReplicationNews:

http://www.AudioAsylum.com/audio/ge...ssages/977.html
The guy writing this message obviously doesn't know what he's talking about with respect to DVD-A. DVD players read at >1X and maintain a LARGE set of data buffers. Nothing about the detailed layout of the disc (pit jitter etc) has an effect on this system.

And again, it seems clear that people were complaining "the CD doesn't sound like the master" and nobody actually determined why in any rigorous technical sense. They seem to have just started throwing up theories, and run with them without substantiation.
 

Lee Scoggins

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But note the numbers - nanosecond jitter causes noise at -90 dB on a 10 kHz sine, that is already less noise than the typical receiver introduces internally... picosecond jitter would be completely swamped by the other sources of noise in the audio chain and the listening environment.
No it would not be swamped. In the Benjamin and Gannon paper, they show that timing differences particularly affect higher frequencies at much higher rates. If you assume -90db at 10khz, you are likely clearly audible at 20khz. Perhaps this explains the increased sonic clarity of low jitter sources.
 

LanceJ

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The ear is more sensitive than a good oscilloscope/microphone combination? Hmmm, very debatable.

But from a factual point of view, unfortunately the ear is connected to an extremely complex analyzing device. A not-perfect (though still awe inspiring) device that is full of beliefs, conflicting emotions, vague ideas, random factoids and on and on and on.

Once a piece of raw data from one of its various sensors is thrown into this incredibly complex sea of neuronic activity, it is put through all kinds of processes to cause it to (hopefully) transform into a meaningful conclusion for whatever is being debated. Processes that aren't always yes/no, black/white or on/off.

DBTs remove much of a person's "gray area" thinking processes (no pun intended!) that cause perceptual inaccuracies, i.e. DBTs allow raw data to flow through more logical (yes/no, etc.) decision-making pathways that lead to more accurate conclusions.

LJ
 

Lee Scoggins

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DBTs remove much of a person's "gray area" thinking processes (no pun intended!) that cause perceptual inaccuracies, i.e. DBTs allow raw data to flow through more logical (yes/no, etc.) decision-making pathways that lead to more accurate conclusions.
I think there are a couple points here that may be dangerous:

1. Logical processes are not the best representation of music. Music is created with passion and emotion.

2. On/off switches are by definition not good at handling gray areas or midway values, which exist in spades in music. Each note's attack - sustain - decay has highly variable lengths and tones. It is difficult to see where more accuracy would be had from yes/no inferences.

There are select cases where perceptions may influence one's evaluation of audio equipment but with critical listening skills, subjective tests and listening are often very valuable at picking up things that many DBTs would miss.

DBTs are difficult to design to work properly, statistically difficult to implement, and hence they are sparse in the scientific literature when it comes to audio phenomena, particularly audio gear evaluation.
 

Lee Scoggins

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And yet no DBTs that compare transports? Published? Peer-reviewed?
Good point John. :)

The burden of proof should be on the DBT proponents. If I am required to offer up definitive peer-reviewed evidence of low jitter audibility, then why not a burden on people to produce papers where it is found that jitter has no audibility to these levels?

I have found out that 20ps is the current audibility threshold among the AES academics.

If I can secure the relevent papers, I will summarize the findings and give the proper citations.

:)
 

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