Would it be fair to say that you turned the volume up to listen to the fade out?

• Better leave the "input gain control" untouched. It added considerable amounts of noise in my case.
• Even if OS X allows different settings for input and output sample rate in the audio/midi control panel for the MBP, you get aliasing if you actually use it.

I recall all posted samples and claims! 

Turns out, the difference was the ADC and test setup, not the DACs!
Two findings for MBP owners:

• Better leave the "input gain control" untouched. It added considerable amounts of noise in my case.
• Even if OS X allows different settings for input and output sample rate in the audio/midi control panel for the MBP, you get aliasing if you actually use it.

The problem I generally see with externally generated jitter, either through up-/downsampling or electronically, is the applicability of those results. You can take it so far, that you can hear at least something, i. e. what jitter of model m at gain g does or does not sound like. After that you will have several pairs m, g that seem to be relevant. But those then have to be translated and tested against real world implementations.

Quote from: rpp3po on 2009-07-21 00:07:13

The problem I generally see with externally generated jitter, either through up-/downsampling or electronically, is the applicability of those results. You can take it so far, that you can hear at least something, i. e. what jitter of model m at gain g does or does not sound like. After that you will have several pairs m, g that seem to be relevant. But those then have to be translated and tested against real world implementations.

The way I see to address that situation is to simply know what kinds of jitter exist in the real world, and duplicate them.  I learned quite a bit about jitter by testing equipment for my now-defunct www.pcavtech.com web site. The most common kind of really heavy jitter is related to the power line frequency.  Frame rates also show up fairly frequently. While quite a bit has been written about self-jitter, it is not all that common at levels that are likely to be heard.

Quote from: Arnold B. Krueger on 2010-04-07 02:16:45

Quote from: rpp3po on 2009-07-21 00:07:13

The problem I generally see with externally generated jitter, either through up-/downsampling or electronically, is the applicability of those results. You can take it so far, that you can hear at least something, i. e. what jitter of model m at gain g does or does not sound like. After that you will have several pairs m, g that seem to be relevant. But those then have to be translated and tested against real world implementations.

The way I see to address that situation is to simply know what kinds of jitter exist in the real world, and duplicate them.  I learned quite a bit about jitter by testing equipment for my now-defunct www.pcavtech.com web site. The most common kind of really heavy jitter is related to the power line frequency.  Frame rates also show up fairly frequently. While quite a bit has been written about self-jitter, it is not all that common at levels that are likely to be heard.

That's part of the problem though: it's hard to know what jitter really does to the signal.

I have read a few papers on modelling jitter in the last days, and yet am not exactly sure what is going on.

I suppose because it presumably depends on the DAC, which is hard to model.

Most papers I've looked at do give explicit models, but they appear to have assumptions on jitter that I find it hard to take on trust (not really, I am sure it is accurate, but with no personal experience of what it "sounds like", they just seem to me to be assertions; I'd like to find a way to avoid those).

I'm running some numerical experiments right now but am not at all convinced by my techniques (lots of perhaps unwarranted assumptions) so will shut up for a while.

My goal is to design products where all of the artifacts produced by the product fall below the threshold of hearing in a silent room.  In order to guarantee inaudibility, I am consciously ignoring masking effects and designing as if the only sound being played was that of the artifacts.  To me this means keeping the sum total of all artifacts at a level that is at least 110 dB below the peak audio levels.  This goal has been achievable in the analog domain for at least 20 years, and for the last 10 years has been achievable in the digital domain.  Achieving these goals requires more engineering, careful circuit layout, and a few more components.  We deliver products that meet these goals in a price range that may seem extravagant to the average consumer ($1000 to $2000).  But, these are very reasonable prices for professional products that will be used in a recording studio on a regular basis.  The hi-end hi-fi enthusiast looks at our products and says "how can it be any good if it only costs $2000"?

The average consumer has no idea how bad their CD player or sound card really is.  There often are no published specifications.

The average consumer has no idea how good or bad their CD player or sound card really is.  They don't know what kind of specifications are required for total freedom from audible artifacts under critical but real  world listening conditions, and most product spec sheets are so incomplete that they don't know how the product compares to the actual requirements.

Quote from: John_Siau on 2009-08-07 16:16:41

My goal is to design products where all of the artifacts produced by the product fall below the threshold of hearing in a silent room.  In order to guarantee inaudibility, I am consciously ignoring masking effects and designing as if the only sound being played was that of the artifacts.  To me this means keeping the sum total of all artifacts at a level that is at least 110 dB below the peak audio levels.  This goal has been achievable in the analog domain for at least 20 years, and for the last 10 years has been achievable in the digital domain.  Achieving these goals requires more engineering, careful circuit layout, and a few more components.  We deliver products that meet these goals in a price range that may seem extravagant to the average consumer ($1000 to $2000).  But, these are very reasonable prices for professional products that will be used in a recording studio on a regular basis.  The hi-end hi-fi enthusiast looks at our products and says "how can it be any good if it only costs $2000"?

I don't see any compelling logic here.

If your goal was to design products where all of the artifacts produced by the artifact fall below the threshold of hearing in a silent room, any reasonable person would say that you are tilting at windmills, given that there are no silent rooms.

A reasonable goal is to design products where no real world customer will hear artifacts in the most silent room that he is likely ever to encounter. A resasonable goal is to design products where no real world customer will hear artifacts while wearing the most isolating earphones in the best room that he is likely ever to encounter.

Quote from: Arnold B. Krueger on 2010-04-07 11:19:46

Quote from: John_Siau on 2009-08-07 16:16:41

My goal is to design products where all of the artifacts produced by the product fall below the threshold of hearing in a silent room.  In order to guarantee inaudibility, I am consciously ignoring masking effects and designing as if the only sound being played was that of the artifacts.  To me this means keeping the sum total of all artifacts at a level that is at least 110 dB below the peak audio levels.  This goal has been achievable in the analog domain for at least 20 years, and for the last 10 years has been achievable in the digital domain.  Achieving these goals requires more engineering, careful circuit layout, and a few more components.  We deliver products that meet these goals in a price range that may seem extravagant to the average consumer ($1000 to $2000).  But, these are very reasonable prices for professional products that will be used in a recording studio on a regular basis.  The hi-end hi-fi enthusiast looks at our products and says "how can it be any good if it only costs $2000"?

I don't see any compelling logic here.

If your goal was to design products where all of the artifacts produced by the artifact fall below the threshold of hearing in a silent room, any reasonable person would say that you are tilting at windmills, given that there are no silent rooms.

A reasonable goal is to design products where no real world customer will hear artifacts in the most silent room that he is likely ever to encounter. A resasonable goal is to design products where no real world customer will hear artifacts while wearing the most isolating earphones in the best room that he is likely ever to encounter.

Recording studios have many audio devices in cascade.

Once you have stated your goal, a reasonable way to proceed would be to model the performance of a product that is just barely noticable in terms of all known audible artifacts. Once you have produced that model, pick a reasonble but somewhat arbitrary number, and set your goal to produce a product that measures that good. For example, if you know all about the audibility of noise and distoriton, then set a goal that is X dB better than that.

Saying that your goal is "A", and then immediately and without any other evidence spouting some arbitrary technical specifications is again, not at all reasonable.

The point is that spouting some arbitrary technical specs isn't a logical way to proceed. The logical way to proceed is to determine the actual thresholds by means of reliable subjective tests,  come up with a reasonable overkill factor for each of them, and built to that balanced overkill design.

Jitter can only be considered totally inaudible if the worst case jitter induced sidebands are at least 23 dB below the A-weighted system noise. Above this level jitter may be audible or it may be masked by the program audio. At Benchmark our goal is to achieve totally inaudible levels of jitter.

Quote

Jitter can only be considered totally inaudible if the worst case jitter induced sidebands are at least 23 dB below the A-weighted system noise. Above this level jitter may be audible or it may be masked by the program audio. At Benchmark our goal is to achieve totally inaudible levels of jitter.

[/size]Any comments on that design goal ?

Quote from: Arnold B. Krueger on 2010-04-10 03:27:11

The point is that spouting some arbitrary technical specs isn't a logical way to proceed. The logical way to proceed is to determine the actual thresholds by means of reliable subjective tests,  come up with a reasonable overkill factor for each of them, and built to that balanced overkill design.

Since this thread is about jitter, let's have a look at a Benchmark statement about jitter:

Quote

Jitter can only be considered totally inaudible if the worst case jitter induced sidebands are at least 23 dB below the A-weighted system noise. Above this level jitter may be audible or it may be masked by the program audio. At Benchmark our goal is to achieve totally inaudible levels of jitter.

[/size]Any comments on that design goal ?

the closest we can come is finding the threshold at which jitter becomes audible and assuming that it is inaudible below that threshold.

Obviously, jitter is one of high end audio's more obvious red herrings.

Quote from: Arnold B. Krueger on 2010-04-12 12:25:56

Obviously, jitter is one of high end audio's more obvious red herrings.

Your TOS8 violation indicates that you have doubts about the Benchmark claim of inaudibility of the jitter effects. On the other hand you state that any halfway CD player has much better jitter performance than LP or analogue tape, which is concidered (proven?) to be no audible problem.
In that case it's probably not unreasonable to assume that the Benchmark jitter performance is far below audibility thresholds ?