[bfreedma]

As I said, when it comes to low cost products, I generally don't bother to measure them either way.

The last relatively expensive DAC I owned that sounded significantly "unusual" in what I would consider to be a bad way, and measured unusual, was a Metrum Octave.
According to our AP analyzer up at Emotiva, it had significant high-frequency rolloff, and rather high THD.
(Note that this is a NOS DAC which uses several somewhat unusual DAC chips and an unusual topology.)
As I recall, the specs called out a frequency response of 20 - 20 kHz +0/-3 dB @ 44k sample rate, so the measured -3 dB at 20 kHz agreed with the published specs.
(However, in terms of performance, I would still characterize it as "not very good".)
The measurements also showed somewhat higher THD in one channel than the other - which seemed to be both out-of-spec and not especially audible.

The last cheap DAC which I recall as sounding especially bad - and whose name I can remember - was a $19 "USB sound card" made by Turtle Beach.
(I don't recall what, if any, specs were provided. Turtle Beach used to be considered to be "a good brand name for computer sound cards".)

As for sounding different...... but NOT measuring noticeably different using the standard measurements....
For several years I owned a Wyred4Sound DAC2 - and I, and several different people I loaned it, all agreed that it audibly emphasized the midrange over other frequencies.
(This characteristic is quite often claimed for DACs that incorporate the Sabre DAC chip.)
Although it offered several different filter options, which did each sound different, listeners agreed that the seeming emphasis of the midrange was present on all of them (including the ones specified as flat).
(I didn't measure that DAC, but it was specified as having a very flat frequency response, and every review I read confirmed that as being true.)

Thanks for the specifics.

The inexpensive Turtle Beach cards had problems but I doubt it they were specific to the DAC. As they were tanking years ago, they released a number of poorly written drivers and used nonstandard interrupts. They didn’t seem to be too concerned about following Windows standards so they exhibited a number of odd issues. No argument that they sounded bad.

Can’t agree with you on the W4S DAC2. I’ve owned one for many years (since the DAC2 was first released) and unless one of the filters was selected, I’ve found it to be neutral as has everyone else who has listened to it. I’ve run a number of blind tests with it and no one has been able to pick it out from any other DAC it’s been compared to. I still have it- happy to setup testing for anyone who would like to participate.

 

[bigshot]

I've compared a $40 Walmart DVD player to a $1200 Oppo HA-1. There was no clear difference there. Is there a different cheap component I should try? Don't bother to reply unless you can name a SPECIFIC MAKE AND MODEL THAT YOU HAVE EXPERIENCED A CLEAR DIFFERENCE WITH UNDER CAREFUL LISTENING CONDITIONS.

I use a Mac for my audio. I know nothing about sound cards, but I know PCs can be noisy. That has nothing to do with the DAC. It's the fault of the computer.

bfreedma, I don't see any point to go to the trouble of testing something that hasn't shown a clear difference under controlled conditions in the past. We could be here until the cows come home spinning our wheels if we do that. I am looking for something that clearly sounds different under careful comparison... specifically blind, level matched, direct A/B switched. It isn't hard at all to do a test like that. If someone isn't willing to even attempt that, they aren't a reliable witness. And it isn't me disqualifying them, it's their own laziness and sloppiness.

 

[gregorio]

[1] If you're really curious about nuclear fission, please consult a good textbook on the subject, or perhaps an employed nuclear physicist....
[1a] Either one will inform you that, if you create a single mass of plutonium that exceeds critical mass, you WILL in fact produce a fission reaction.... (an explosion).
[1b] You might well end up with a small pop... barely strong enough to push the pieces apart... while releasing enough radiation to kill you.
[1c] That's why, when we build bombs, we generally employ additional force to bring the pieces together, and hold them together.
[1d] So, yes, my "hypothetical" is in fact quite true.....

1. Oh good, let's again fall back on the good ol' audiophile tactic of hypocrisy. Why don't you find out some basics about nuclear fission before telling others to?
1a. No, in fact neither one will tell you that! You will get a fission chain reaction but you will NOT get a nuclear explosion! "While the fundamental physics of the fission chain reaction in a nuclear weapon is similar to the physics of a controlled nuclear reactor, the two types of device must be engineered quite differently (see nuclear reactor physics). A nuclear bomb is designed to release all its energy at once, while a reactor is designed to generate a steady supply of useful power." - Wiki.
1b. Hey, you were the one who said "nuclear explosion" and then bought up Hiroshima and Nagasaki, you think the inhabitants were incinerated by "a small pop"?
1c. When we intend a nuclear explosion rather than just a nuclear chain reaction, we always employ a large additional force, it is NEVER just "someone banging together two blocks of plutonium".
1d. Clearly it was NOT true and clearly to any rational person it was nonsense!

[2] As for jitter and DACs... I'm quite inclined to agree that, for most consumers, it isn't worth worrying about.
[2a] Most designers of commercial DACs follow good design practices - which result in relatively low levels of jitter.
[2b] It's also worth noting that measuring the levels of jitter present in most modern equipment is quite difficult.
[2c] The widely quoted "J-Test" DOES NOT measure either jitter, or the results of known amounts of jitter on the audio output, directly.

2. Who are you agreeing with, who are the consumers who aren't "most consumers" and why should they worry about it?
2a. "Relatively low levels of jitter" - Relative to what? Relative to 25 year old mass market built-in components which on average have levels of jitter already several hundred times below audibility? Why would anyone be "worried about" jitter that is "relatively lower" than jitter which is already orders of magnitude below audibility?
2b. Sure, "quite difficult" but clearly entirely possible as there's commercially available instruments which do this. However, this is effectively a circular argument. One of the main reasons it's "quite difficult" is because "the levels of jitter in most modern equipment" are so small (so far below audibility)!
2c. The "J-Test" measures the amount of jitter induced in a device in response to a test signal optimised to produce the highest levels of jitter distortion. IE. A high frequency sine wave at full scale, typically 17kHz. The amplitude of the resultant jitter distortion should exceed the amplitude that would actually occur when reproducing a commercial music recording (as music recordings do not contain full scale 17kHz components). Furthermore, Benjamin/Gannon (and anyone else who has ever used the available equipment) did not use the "J-Test" to measure the jitter.

[1] However, as for DACs in general, it has been my experience, and that of many others, that "all modern DACs do NOT sound the same".
[2] It has also been my experience that many modern DACs DO NOT follow what I would call "good design practices". As a result, some of them have audible flaws, which can be easily related to standard measurements.
[3] (For example one modern expensive NOS DAC I owned had a frequency response that was -3 dB at 20 kHz.... which is probably why it sounded "very smooth".) I will also concede that, when I encounter a $50 product that sounds bad, I often neglect to expend the time and effort to find out why it sounds bad.
[3a] (But I would certainly NOT tell someone who is sure they hear a difference that "they must be wrong"...)

An absolute classic example of audiophile fallacy and myth at work!!!

1. This is not the "your's or many others experiences" forum, it's the Sound Science forum. So if your or others experiences contradict the facts/science then we need some reliable supporting evidence. How many times? The bizarre thing is that YOU ask for reliable evidence, which you're provided with but you refuse to return the required/expected courtesy! How hypocritical is this?

2. So provide some reliable evidence/examples of modern DACs which have such bad "design practices" that they introduce jitter artefacts above the threshold of audibility!

3. So here we have the actual admission and the problem that lies at the heart of so much audiophile BS! You can't be bothered to find out why it sounds bad .... so what do you do? Are you honest and say you don't know why it sounds bad or are you dishonest and simply make-up some BS explanation? And when that explanation is refuted (with reliable evidence) are you honest and admit you don't really know and just made it up or are you dishonest and defend it to the death as at least a possibility, using more made-up nonsense, fallacies, misrepresentations, hypocrisy and any other offensive tactic you can think of? You even give an example of this right before your admission! What are the actual facts about the amount of 20kHz content found in commercial music recordings and how does that align with the reliable evidence/established science concerning the threshold of hearing 20kHz content? You haven't defined "very smooth", you haven't provided any reliable evidence that you could actually hear any difference and you've just made-up an explanation that according to the facts/science is NOT "probable" it's AT LEAST highly improbable!
3a. Again, you're just repeating one of your favourite types of fallacy! If someone states they hear a difference I/we would generally presume they are NOT wrong (that they are hearing a difference). However, their explanation of why they're hearing a difference and/or what specifically they're hearing a difference between, sometimes/often "must be wrong" and I certainly would tell them that!

Round and round we go.

G

 

[bfreedma]

I've compared a $40 Walmart DVD player to a $1200 Oppo HA-1. There was no clear difference there. Is there a different cheap component I should try? Don't bother to reply unless you can name a SPECIFIC MAKE AND MODEL THAT YOU HAVE EXPERIENCED A CLEAR DIFFERENCE WITH UNDER CAREFUL LISTENING CONDITIONS.

I use a Mac for my audio. I know nothing about sound cards, but I know PCs can be noisy. That has nothing to do with the DAC. It's the fault of the computer.

bfreedma, I don't see any point to go to the trouble of testing something that hasn't shown a clear difference under controlled conditions in the past. We could be here until the cows come home spinning our wheels if we do that. I am looking for something that clearly sounds different under careful comparison... specifically blind, level matched, direct A/B switched. It isn't hard at all to do a test like that. If someone isn't willing to even attempt that, they aren't a reliable witness. And it isn't me disqualifying them, it's their own laziness and sloppiness.

Agree in general on testing, but still willing to offer it if it helps move the ball forward.

PCs are no noisier./less noisy in general than Macs these days. They are all built using the same parts, buses, and processors. For whatever reason, Apple still manages to sell commodity parts at a premium by utilizing a closed model. Differentiation is really just a matter or the respective OS's and available software.

 

[KeithEmo]

I'm beginning to suspect that I know a lot more about nuclear fusion than you do.... but I'm beginning to lose interest in explaining it .... or in arguing about the semantic details of how violent a fission reaction must be for one or the other of us to classify it as "an explosion". (However, as an example, it clearly is not going to serve our purpose here... )

Your comment about J-Test is entirely true .... but it also provides an excellent example of the problem at hand. The correct and accurate way to measure the amount of self jitter present in a circuit is to actually measure it. And the correct and accurate way to measure the susceptibility of a circuit to external jitter present on the source is to apply source signals containing various precisely known amounts of jitter and measure the results. J-Test does neither of these. It is, instead, as you say, is "optimized to produce the highest levels of jitter" - ASSUMING SPECIFIC CHARACTERISTICS OF THE INPUT CIRCUIT USED. However, you will never know how much jitter that test signal will produce with a given circuit, and it is never directly measured. Therefore, you are in fact testing how the specific circuit will react untder one specific condition.... which is a very different matter.... and tells you far less. I could, for example, create an input circuit that performed very well under J-test, but produced massive amounts of jitter under other circumstances. (Any circuit which had a large amount of self-jitter, but which failed to produce extra jitter while passing that specific signal quild fit that description.) Therefore, J-Test, while useful, neither measures the actual self-jitter already present in a circuit, nor the amount of additional distortion that applying an input signal containing a specific amount of jitter will produce from that circuit. The result is interesting - it just isn't telling you those things.... so they go untested.

I agree, the levels of jitter present on modern equipment are difficult to measure "because they are so low"....
However, claiming that this also "proves" that they are inaudible is the circular argument....
They are low enough that measuring them is difficult....
This has no relevance whatsoever as to whether those levels are or are not audible....
(Things that are audible are in no way obligated to be either large or easy to measure.)
Likewise, the amounts that are present in commercial recordings has nothing whatsoever to do with what is or is not audible.
(We are NOT going to simply accept that "commercial recordings contain inaudible amounts of jitter"... which is why we're talking about actually testing it.)
Likewise, jitter may be present for any of several reasons besides the single specific mechanism J-Test uses to produce it.

1. Oh good, let's again fall back on the good ol' audiophile tactic of hypocrisy. Why don't you find out some basics about nuclear fission before telling others to?
1a. No, in fact neither one will tell you that! You will get a fission chain reaction but you will NOT get a nuclear explosion! "While the fundamental physics of the fission chain reaction in a nuclear weapon is similar to the physics of a controlled nuclear reactor, the two types of device must be engineered quite differently (see nuclear reactor physics). A nuclear bomb is designed to release all its energy at once, while a reactor is designed to generate a steady supply of useful power." - Wiki.
1b. Hey, you were the one who said "nuclear explosion" and then bought up Hiroshima and Nagasaki, you think the inhabitants were incinerated by "a small pop"?
1c. When we intend a nuclear explosion rather than just a nuclear chain reaction, we always employ a large additional force, it is NEVER just "someone banging together two blocks of plutonium".
1d. Clearly it was NOT true and clearly to any rational person it was nonsense!

2. Who are you agreeing with, who are the consumers who aren't "most consumers" and why should they worry about it?
2a. "Relatively low levels of jitter" - Relative to what? Relative to 25 year old mass market built-in components which on average have levels of jitter already several hundred times below audibility? Why would anyone be "worried about" jitter that is "relatively lower" than jitter which is already orders of magnitude below audibility?
2b. Sure, "quite difficult" but clearly entirely possible as there's commercially available instruments which do this. However, this is effectively a circular argument. One of the main reasons it's "quite difficult" is because "the levels of jitter in most modern equipment" are so small (so far below audibility)!
2c. The "J-Test" measures the amount of jitter induced in a device in response to a test signal optimised to produce the highest levels of jitter distortion. IE. A high frequency sine wave at full scale, typically 17kHz. The amplitude of the resultant jitter distortion should exceed the amplitude that would actually occur when reproducing a commercial music recording (as music recordings do not contain full scale 17kHz components). Furthermore, Benjamin/Gannon (and anyone else who has ever used the available equipment) did not use the "J-Test" to measure the jitter.


An absolute classic example of audiophile fallacy and myth at work!!!

1. This is not the "your's or many others experiences" forum, it's the Sound Science forum. So if your or others experiences contradict the facts/science then we need some reliable supporting evidence. How many times? The bizarre thing is that YOU ask for reliable evidence, which you're provided with but you refuse to return the required/expected courtesy! How hypocritical is this?

2. So provide some reliable evidence/examples of modern DACs which have such bad "design practices" that they introduce jitter artefacts above the threshold of audibility!

3. So here we have the actual admission and the problem that lies at the heart of so much audiophile BS! You can't be bothered to find out why it sounds bad .... so what do you do? Are you honest and say you don't know why it sounds bad or are you dishonest and simply make-up some BS explanation? And when that explanation is refuted (with reliable evidence) are you honest and admit you don't really know and just made it up or are you dishonest and defend it to the death as at least a possibility, using more made-up nonsense, fallacies, misrepresentations, hypocrisy and any other offensive tactic you can think of? You even give an example of this right before your admission! What are the actual facts about the amount of 20kHz content found in commercial music recordings and how does that align with the reliable evidence/established science concerning the threshold of hearing 20kHz content? You haven't defined "very smooth", you haven't provided any reliable evidence that you could actually hear any difference and you've just made-up an explanation that according to the facts/science is NOT "probable" it's AT LEAST highly improbable!
3a. Again, you're just repeating one of your favourite types of fallacy! If someone states they hear a difference I/we would generally presume they are NOT wrong (that they are hearing a difference). However, their explanation of why they're hearing a difference and/or what specifically they're hearing a difference between, sometimes/often "must be wrong" and I certainly would tell them that!

Round and round we go.

G

 

[KeithEmo]

Perhaps I can provide a little more information - just for the record.

1a. A reactor uses a sub-critical nuclear reaction. In order to achieve critical mass, you must have a certain mass of fuel, within specific proximity. Since a sphere is the densest concentration of mass - a sphere is the shape for which the amount necessary to achieve critical mass is the lowest. In a reactor, either the fuel is held further apart, or it is diluted by being alloyed by other metals, or areas of other materials (like control rods) are placed between various parts of the fuel. The reaction is essentially the same - although reactors are built in such a way as to prevent a critical mass reaction from occurring.

1b. By current definitions, the explosions at Hiroshima and Nagasaki were relatively small, and relatively inefficient.... Each yielded less than a single megaton of energy and, by all current estimates, only a small percentage of their fuel was actually converted into energy.

1c. Absolutely, when we want a controlled nuclear reaction, rather than an uncontrolled reaction, we design the mechanism quite differently.
A bomb is designed with the intent of producing a critical reaction; a reactor is designed to avoid even the possibility of that occurring (hopefully).

1d. I'm still waiting to see the part that isn't true.

2a. Relative to the levels present on older equipment... and relative to the levels which are easily heard or measured. Since you seem so sure that "the level of audibility for jitter is well known" and "modern equipment is all far below it", perhaps you can tell me why so many people seem worried about it.... Perhaps they don't agree with YOUR opinion about what level is audible. Obviously, however, considering the amount of discussion on the subject, a lot of people are in fact "worried about it".

2b. Difficult is always relative. However, from the fact that so many reviewers resort to compromises like J-Test, rather than actually measuring jitter, it is safe to assume that at least they find it difficult to measure. I can tell you that, in order to measure jitter directly, using the current models of Audio Precision equipment used by most manufacturers, you need to add an optional hardware module, which adds about $10k to the $50k - $60k price of the more standard version. In terms of dicciculty in taking the actual measurements, because jitter is strongly affected by circuit characteristics like stray capacitance, the measurement conditions have a major impact on the measurements. (Moving the test probe a few inches, or testing with the cover on or off, will often produce quite different readings. This makes it difficult to acquire consistent and accurate measurements.)

2c. J-Test is what it is... which is a simple, and easy to use, test which provides a very general indicator for "how susceptible a device is to certain common types of jitter". (Data-correlated jitter produced by certain types of circuits when subjected to certain test signals.) It also serves a useful purpose for vetting designs. AS A VERY BROAD GENERALIZATION, devices and circuits that perform poorly with J-Test also perform poorly under other conditions. However, as with most generalizations, that doesn't hold true at all in specific. For example, because it involves higher frequencies, J-test tells us nothing about how susceptible a circuit is to low frequency speed variations. (Jitter covers a range from a small fraction of one Hz to several kHz.... but J-Test only covers a narrow subset of that range.... and using a single waveform.)

In point of fact, and exactly opposite of what you continually claim, I DID in fact say "I don't know why they all sounded bad".
I am NOT the one who keeps ruling out possible explanations "because I know they aren't audible"....
I'm the one who isn't sure which ones are or are not audible (if I knew that then there would be nothing to discuss in this forum).

1. Oh good, let's again fall back on the good ol' audiophile tactic of hypocrisy. Why don't you find out some basics about nuclear fission before telling others to?
1a. No, in fact neither one will tell you that! You will get a fission chain reaction but you will NOT get a nuclear explosion! "While the fundamental physics of the fission chain reaction in a nuclear weapon is similar to the physics of a controlled nuclear reactor, the two types of device must be engineered quite differently (see nuclear reactor physics). A nuclear bomb is designed to release all its energy at once, while a reactor is designed to generate a steady supply of useful power." - Wiki.
1b. Hey, you were the one who said "nuclear explosion" and then bought up Hiroshima and Nagasaki, you think the inhabitants were incinerated by "a small pop"?
1c. When we intend a nuclear explosion rather than just a nuclear chain reaction, we always employ a large additional force, it is NEVER just "someone banging together two blocks of plutonium".
1d. Clearly it was NOT true and clearly to any rational person it was nonsense!

2. Who are you agreeing with, who are the consumers who aren't "most consumers" and why should they worry about it?
2a. "Relatively low levels of jitter" - Relative to what? Relative to 25 year old mass market built-in components which on average have levels of jitter already several hundred times below audibility? Why would anyone be "worried about" jitter that is "relatively lower" than jitter which is already orders of magnitude below audibility?
2b. Sure, "quite difficult" but clearly entirely possible as there's commercially available instruments which do this. However, this is effectively a circular argument. One of the main reasons it's "quite difficult" is because "the levels of jitter in most modern equipment" are so small (so far below audibility)!
2c. The "J-Test" measures the amount of jitter induced in a device in response to a test signal optimised to produce the highest levels of jitter distortion. IE. A high frequency sine wave at full scale, typically 17kHz. The amplitude of the resultant jitter distortion should exceed the amplitude that would actually occur when reproducing a commercial music recording (as music recordings do not contain full scale 17kHz components). Furthermore, Benjamin/Gannon (and anyone else who has ever used the available equipment) did not use the "J-Test" to measure the jitter.


An absolute classic example of audiophile fallacy and myth at work!!!

1. This is not the "your's or many others experiences" forum, it's the Sound Science forum. So if your or others experiences contradict the facts/science then we need some reliable supporting evidence. How many times? The bizarre thing is that YOU ask for reliable evidence, which you're provided with but you refuse to return the required/expected courtesy! How hypocritical is this?

2. So provide some reliable evidence/examples of modern DACs which have such bad "design practices" that they introduce jitter artefacts above the threshold of audibility!

3. So here we have the actual admission and the problem that lies at the heart of so much audiophile BS! You can't be bothered to find out why it sounds bad .... so what do you do? Are you honest and say you don't know why it sounds bad or are you dishonest and simply make-up some BS explanation? And when that explanation is refuted (with reliable evidence) are you honest and admit you don't really know and just made it up or are you dishonest and defend it to the death as at least a possibility, using more made-up nonsense, fallacies, misrepresentations, hypocrisy and any other offensive tactic you can think of? You even give an example of this right before your admission! What are the actual facts about the amount of 20kHz content found in commercial music recordings and how does that align with the reliable evidence/established science concerning the threshold of hearing 20kHz content? You haven't defined "very smooth", you haven't provided any reliable evidence that you could actually hear any difference and you've just made-up an explanation that according to the facts/science is NOT "probable" it's AT LEAST highly improbable!
3a. Again, you're just repeating one of your favourite types of fallacy! If someone states they hear a difference I/we would generally presume they are NOT wrong (that they are hearing a difference). However, their explanation of why they're hearing a difference and/or what specifically they're hearing a difference between, sometimes/often "must be wrong" and I certainly would tell them that!

Round and round we go.

G

 

[bigshot]

I'm imagining our friend is like the sign in the old silent comedies that blows around in the wind and ends up pointing to the road to the quarry pit instead of the road to the big city. He spins around and always ends up pointing the wrong direction.

Does anyone care about nuclear reactors? It's just a diversionary tactic to get the conversation away from pointing out his mistakes.

 

[castleofargh]

I agree, the levels of jitter present on modern equipment are difficult to measure "because they are so low"....
However, claiming that this also "proves" that they are inaudible is the circular argument....
They are low enough that measuring them is difficult....
This has no relevance whatsoever as to whether those levels are or are not audible....
(Things that are audible are in no way obligated to be either large or easy to measure.)

while the idea is correct, in the sense that cause and consequence could have intermediaries being strongly influenced by small initial change(at least in some specific cases reaching some operating threshold). but I can't think of many examples where something is hard to measure but conclusively perceived by ear. your argument would push us to forget jitter measurement itself, and go look for the potential impact at the output signal, which is kind of what we do already. making it even less likely to find a situation where we're going to hear something but have a hard time measuring it. at best we're going to have a hard time identifying the cause of the measured change at the output, which is a very different problem.

 

[bigshot]

If you can hear it, it's audible. If it falls below the threshold of perception, it isn't. You can establish what the threshold is by measuring the point of just detectable difference. The JDD threshold for jitter is an order of magnitude more than jitter as it occurs in even the cheapest audio components. Jitter is not an issue that is worth considering when shopping for audio equipment. It's just a metric used by audio salesmen to get people to spend money they really don't have to spend.

 

[KeithEmo]

I agree entirely....

Phenomena like jitter cover a huge range of possible variations.... from slow clock drift over tens of seconds to modulation products that may occur at tens of kHz.... and from specific waveforms, to purely random, to data-correlated.
- I wouldn't necessarily expect 100 picoseconds of sine wave jitter at 3 kHz and 100 picoseconds of random jitter at 0.1 Hz to be equally audible.
- And I wouldn't expect a slow speed variation that takes place over several seconds to be as audible as one that occurs abruptly several time a second.
- And, likewise I wouldn't necessarily expect the same 100 picoseconds of sine wave jitter at 3 kHz to be equally as audible with a pure sine wave test signal as it is with music.

However, to make things even more complicated, it is quite often difficult to isolate one difference, like jitter, among others.
Many devices that have different amounts of jitter probably also have other differences......
In the case of DACs, that might include noise, distortion of various types, and ringing of various types., or even some other factors none of us have even considered so far.
And, in the case of devices that perform resampling, it may also include more complex and unique differences between the input and output signals.

For example, the AD1986 ASRC is specified to deliver an output signal whose output is "identical to what it theoretically should be down to about 132 dB" - but they entirely fail to specify what the actual differences may be.
So, perhaps those unspecified differences to account for the fact that so many people insist that they hear a difference between when that chip is engaged and when it is bypassed.
Or perhaps it really simply reduces jitter - and the difference they're hearing is the lack of jitter (we've avoided considering the possibility that small amounts of certain types of jitter may be heard as an improvement rather than as a flaw).
Or perhaps there is some other difference being introduced along with the reduction in jitter.
(Or perhaps everyone who claims to hear a difference really is imagining it.)

To me, it makes more sense to approach the question from the direction of:
"We've identified a difference, which multiple people claim to hear... let's confirm that it's really there."
"Then, once we've done that, we can proceed to some theories about what's causing it, and some experiments to determine which of those theories might be correct."
However, it is not good science to simply ignore claims made by others because you can't find a theory to explain them.

Remember the experiment where sighted observers consistently agreed that bright green meat didn't taste the same as meat that was normally colored?
Further experimentation has shown conclusively that......
- the meat itself tasted no different
- yet none of the subjects were lying or imagining the difference
It turned out that there are actually links in our brains that allow what we see to actually influence what we taste.
(Yet we would never have learned that important fact if we'd simply "written off" those results as "imaginary".)

I absolutely agree that, if two DACs sound noticeably different, odds are that the difference is not being caused by differences in the amount or type of jitter...
(I can think of several other explanations that seem to be more likely to me.)
However, since I don't know for sure, I am NOT willing to give advice to other people, based on an assumption that I DO know for sure...
I prefer to limit myself to claims that are actually defensible... such as "IN MY OPINION I doubt it matters" or even "There is nothing I know of in our present scientific knowledge to support that claim".

Maybe it will turn out that test subjects consistently find that DACs with black knobs really do sound better than ones with silver knobs - but only if they can see the color of the knobs...
Since we KNOW that such a situation occurs with the taste of steak it seems not at all unreasonable to suspect that a similar link might exist between "perceived sound quality and knob color".
If so, it makes more sense to me to determine that correlation, so we can take it into account, rather than to simply continue to deny that it might exist, and argue that everyone who claims it does "must be imagining it".
(And, if it turned out to be the case, I would cheerfully classify it under the branch of SCIENCE we call "psychoacoustics" or the one we call "neuroscience"... since they are both types of "science related to audio".)

while the idea is correct, in the sense that cause and consequence could have intermediaries being strongly influenced by small initial change(at least in some specific cases reaching some operating threshold). but I can't think of many examples where something is hard to measure but conclusively perceived by ear. your argument would push us to forget jitter measurement itself, and go look for the potential impact at the output signal, which is kind of what we do already. making it even less likely to find a situation where we're going to hear something but have a hard time measuring it. at best we're going to have a hard time identifying the cause of the measured change at the output, which is a very different problem.

 

[Sgt. Ear Ache]

I'm interested to know about any PROVABLY (as in blind tested) audible sound quality that isn't also measurable in some way.

 

[bigshot]

Certainly there is nothing that we can record that is audible but not measurable. If we can record it, we can measure it.

If I'm allowed to offer an even less direct answer to your question... Voices in your head are audible but not measurable. kill your parents

 

[Sgt. Ear Ache]

Certainly there is nothing that we can record that is audible but not measurable. If we can record it, we can measure it.

If I'm allowed to offer an even less direct answer to your question... Voices in your head are audible but not measurable.

Oh, I completely accept the inarguable fact that imaginary sounds are not measurable!

 

[bigshot]

There are plenty of unmeasurable sounds that are imaginary too... bias and placebo are two big causes.

 

[colonelkernel8]

None idiophile device.

It is, basically, a thin disc that is placed atop the CD ( or better yet, DVD ) in all top loading and tray loading transports. There have been special paper, graphite and carbon fibre mats sold for this purpose. In practice, 0.2 mm ( or thereabouts ... ) mm thick carbon fibre version proved to be the most durable.

It is required in all transports that do not offer the support for the optical disk across its entire surface. Why, do you think, older Pioneer CD players and CD-R/RW recorders with "turntable" support in the exact size of the disk, on which you place CD with the recorded side facing up/towards you, are creating bidding wars on ebay - if and when they appear for sale ?



Naturally, turntable style CD transport costs more than standard variety - and reading errors that do occur in real time ( listening directly from a CD player, without the possibility for as many "passes" as required for perfect rip ) then have to be corrected for. No matter how sophisticated is error correction system/algorythm - it can NOT beat no error ( or, at least, less errors ) offered by turntable style support or, next best thing, CD mats used atop CDs ( or DVDs) in standard transports.

There is one application that requires warning :
DO NOT USE CD MAT IN ANY CD-DRIVE THAT (CAN) OPERATE AT MORE THAN ABOUT 4X NORMAL SPEED - such as with CD/DVD burners.

Dimensions of CD hole, CD spindle clamp and CD mat have some tolerance; and it is possible that clamp will not clam the mat 100% in centre each and every time. If spun faster than about 4x, it can create havoc. I grew a custom to tick each and every box in whatever CD/DVD burning software to bring the speed of rotation DOWN - and as an extra precaution, burn at first a normal CD-R without the CD mat ...- since sometimes various settins interfere with each other and the computer will try to e "helpful" and increase the speed. This unfortunately also prevents verification of the written data at the end of burning - as this operation can not be made to turn more slowly, but will usually run at max speed the drive used is capable of. Most definitely not something one would want ...

There are also exceptions where the use of mats is impossible; those drives that only have a very narrow slot in which the optical disk is inserted. That additional 0.2 mm simply does not go in. Among others, Yamaha has such drives.

The diff use of CD mat can make ? A friend cursed me for not having demoed the CD mat to him before he replaced his CD recorder with newer CD player - because the new CD player no longer had the edge over older CD recorder ,but now using CD mat - the very reason why he purchased the new CD player in the first place.

It was inevitable - everything invented in the West gets copied, sooner or later, at a much lower cost in China. The first hit for CD mat on today's ebay :
https://www.ebay.de/itm/0-2mm-Kohle...566190?hash=item34085c4d2e:g:ZZ0AAOSwtLNcrxVZ

lol. I don't think you understand how ridiculous this is. Does the laser impart a force on the CD greater than something measured in femtonewtons? I just don't understand why you're here. "Demoing" a product is not the same as testing it. I'd bet every penny I make for the rest of my life that a CD mat does absolutely nothing to the signal in an already functioning CD player. Plus, read errors don't manifest themselves as "less bass" or "too much treble" or god forbid "narrow soundstage", they manifest as skips or pops.