[BiggerHead]

 
I understand exactly what you have pointed out and if there is enough noise being transmitted through the USB cable to the analog side of the DAC so that the noise is having an audible effect, then there are serious problems with the devices at each end of the USB cable, i.e. the digital source and the USB DAC, and these problems will not be resolved by simply replacing the USB cable.

 
I agree that it's not clear that any improved quality cable could do much for it.  A ferrite core might help.  I'm not sure I'd call it "serious problems" or at least it's not clear to me that it's unusual. But any cable that connects the grounds of the two powered devices is going to make a ground loop, and ground loops pick up noise along the whole loop, not just the cable, so shielding it won't necessarily fix that, nor will shielding it prevent transmission of noise from the computer's ground.  If I was worried about it, I'd be looking at isolation solutions. (Is there something wrong with optical inputs?) Anyway, this addresses a specific problem obviously.  It doesn't reduce distortion or flatten your FR.

 

[mmerrill99]

In my experience RF noise on digital inputs flattens the sound, lessens the dynamics, makes for an uninteresting sound - this is obviously only noticeable when music is playing

That sadly is really not very helpful as it is a personal experience that does not generalize or transfer.

But is it a personal experience of any lesser value than your experience of " amp cranked to max I cannot hear any noise whatsoever with FooBar on pause or playing back digital silence. Whatever noise is gathered by the USB cable does not seem to make it out the analog end to any great degree"

However, it may be that some of these elements can be translated into quantifiable elements.

You suggest the dynamic range is decreased, that at least is measurable, but this perception of lowered dynamic range can as I understand it be caused by higher noise floors which again is easily measurable.

I have no way of accurately interpreting what you mean by flatten or uninteresting - can you define these in other terms - are these synonyms for lower dynamic range ? that is not a rhetorical question. 

What I spoke of were my perceptions of the issues that noise in digital audio systems often cause - they were my best attempt at descriptions of my auditory perception of these issues.

 

[gregorio]

In my experience RF noise on digital inputs flattens the sound, lessens the dynamics, makes for an uninteresting sound ...

 
Have you tried reversing the USB cable? Maybe that would sharpen the sound, increase the dynamics and make for a more interesting sound ... maybe even more so than was actually intended/recorded!

 

What I spoke of were my perceptions of the issues that noise in digital audio systems often cause - they were my best attempt at descriptions of my auditory perception of these issues.

 
Well, well, well, what do you know, now we get to the real heart of the matter! Or more likely, we're only just starting to get to the real heart of the matter because for many audiophiles the definition of the word "perception" does not apply to them, only to other, lesser beings. In the audiophile dictionary, the definition of "perception" is changed from a "mental impression" or an "interpretation of reality" to; perception = reality! So, maybe we're actually getting somewhere ... or maybe not?
 
G

 

[ralphp@optonline]

   
Have you tried reversing the USB cable? Maybe that would sharpen the sound, increase the dynamics and make for a more interesting sound ... maybe even more so than was actually intended/recorded!

G

That's a very good idea. Last night I ran a little experiment with my USB cable. I disconnected it from the USB DAC and put a simple knot in the USB cable and reconnected it the USB DAC. When I resumed playing some music sure enough the music sounded all congested and disorganized, kind of like it was tied up in knots! I undid the knot and low and behold the music was back to normal, well as normal as it could be with the digital noise but that's another issue.
 
Regarding the digital noise I'm thinking about how to remove all the noise that has built up over time on the external hard drive that I use to store my digital audio files. One idea is give the drive to my wife to bring with her to yoga class. Perhaps the calming effect of yoga will help to relax the files and quiet all the digital noise. What do you think?

 

[Magic Man]

That's a very good idea. Last night I ran a little experiment with my USB cable. I disconnected it from the USB DAC and put a simple knot in the USB cable and reconnected it the USB DAC. When I resumed playing some music sure enough the music sounded all congested and disorganized, kind of like it was tied up in knots! I undid the knot and low and behold the music was back to normal, well as normal as it could be with the digital noise but that's another issue.

I like to use a longer USB cable when listening to rock music to allow the lower depth. I find dropping the centre of the cable lower than the source also helps to accentuate the perception of bass, sort of sing cable shaping as a dynamic equaliser.








/s

 

[ralphp@optonline]

I like to use a longer USB cable when listening to rock music to allow the lower depth. I find dropping the centre of the cable lower than the source also helps to accentuate the perception of bass, sort of sing cable shaping as a dynamic equaliser.

Seems that cables are not just directional but also very sensitive to alignment/placement as well. If the cable is too elevated then the music will become peaky, if the cable is overly long the music will drag and too short and the music becomes too quick. I think that we've stumbled on a whole new area to explore and, more importantly, to obsess about!

 

[mmerrill99]

I understand what you are saying - that DACs should be totally immune to any noise on their inputs - it's a nice engineering goal but how realistic is it? Do you really have a grasp on what's needed to achieve this? Do you have any examples of such DACs?

I don't understand the relevance of this.

One could also try to reduce the RF noise coming from the various devices.

As I said do you really understand the real-world nature of what you are talking about? You have stated that any DAC which allows such noise to become noticeable in it's output is broken & should be changed - so is this not your solution rather than trying to reduce RF noise so that "broken DACs" will be improved?

The relevance is that throwing in the whole RF noise issue, an issue which lies in the analog domain, when the discussion was about the digital domain is a bit of a deflection. However it does raise a possible issue. One thing I've noticed about the kind of RF noise we are speaking of is that it's effect on the sound is not subtle and is very clearly and quite audible has in noise and static.

Who said the discussion SHOULD be limited to the digital domain - I don't see that in the title or the op. I certainly don't consider it a deflection - it's a system-wide view of the matter & doesn't try to push one agenda.
I presume the RF noise you are talking about is the high-pitched whine & static heard when such ground loop issues are very severe - according to you your DAC must have been a "broken DAC" - care to tell us which one so we can avoid it?. You know - protect the unwitting consumer from throwing their money away on garbage like "broken DACs"

At a lesser noise levels these obviously audible differences aren't evident & only have their effect when music is playing (a the perceived issues I already mentioned) - this secondary effect of the noise tends only to be noticed as an audible difference when it is removed.

 

[mmerrill99]

What I spoke of were my perceptions of the issues that noise in digital audio systems often cause - they were my best attempt at descriptions of my auditory perception of these issues.

Well, well, well, what do you know, now we get to the real heart of the matter! Or more likely, we're only just starting to get to the real heart of the matter because for many audiophiles the definition of the word "perception" does not apply to them, only to other, lesser beings. In the audiophile dictionary, the definition of "perception" is changed from a "mental impression" or an "interpretation of reality" to; perception = reality! So, maybe we're actually getting somewhere ... or maybe not?

G

Well, yes, auditory perception is the real heart of the matter & something that everyone in this SOUND science section would do well to inform themselves about. Too often we see posts here that demonstrate an underlying confusion about auditory perception, - there's not a one-to-one relationship between auditory perception & air vibrations. We often see stated here a perceived effect assumed to be directly related to a simplistic & easily measured difference in the air vibrations i.e bright sounding = measurable HF frequency difference ; perceived dynamic range = standard DR measurement, etc.

 

[ralphp@optonline]

As I said do you really understand the real-world nature of what you are talking about? You have stated that any DAC which allows such noise to become noticeable in it's output is broken & should be changed - so is this not your solution rather than trying to reduce RF noise so that "broken DACs" will be improved?
Who said the discussion SHOULD be limited to the digital domain - I don't see that in the title or the op. I certainly don't consider it a deflection - it's a system-wide view of the matter & doesn't try to push one agenda.
I presume the RF noise you are talking about is the high-pitched whine & static heard when such ground loop issues are very severe - I presume you were also using a "broken DAC" - care to tell us which one so we can avoid it?.

At a lesser noise levels these obviously audible differences aren't evident & only have their effect when music is playing (a the perceived issues I already mentioned) - this secondary effect of the noise tends only to be noticed as an audible difference when it is removed.

You keep on trying to inject all this audiophile nonsense into the discussion and I keep on ignoring you. I think that this is good way to exchange information.
 
All the issues you bring up only appear in high end audio publications and on high end audio forums - the issues just do not occur in real world audio systems unless something is BROKEN. Is that clear enough?

 

[ralphp@optonline]

Well, yes, auditory perception is the real heart of the matter & something that everyone in this SOUND science section would do well to inform themselves about. Too often we see posts here that demonstrate an underlying confusion about auditory perception, - there's not a one-to-one relationship between auditory perception & air vibrations. We often see stated here a perceived effect assumed to be directly related to a simplistic & easily measured difference in the air vibrations i.e bright sounding = measurable HF frequency difference ; perceived dynamic range = standard DR measurement, etc.

Why is it only measurements need to adhere to these high standards but sighted listening tests and comparisons do not?

 

[mmerrill99]

Well, yes, auditory perception is the real heart of the matter perceived dynamic range = standard DR measurement, etc.

Why is it only measurements need to adhere to these high standards but sighted listening tests and comparisons do not?

What high standards? You mean measurements that have any correlation (never even mind causation - that would be the next step) to what is actually perceived? I don't consider that a "high standard" - I would consider it a basic requirement of any measurements i.e that they have a direct, proven relationship to that which is being investigated i.e auditory perception. Unfortunately, most measurements have a bearing on electrical performance, rather than auditory perception - a bit like doing an analysis of the fuel in order to tell us the car driving experience.

I would much rather judge a car's potential to match my expectation of what I want from it by listening to others driving experiences rather than looking at fuel analysis figures!

 

[ralphp@optonline]

What high standards? You mean measurements that have any correlation (never even mind causation - that would be the next step) to what is actually perceived? I don't consider that a "high standard" - I would consider it a basic requirement of any measurements i.e that they have a direct, proven relationship to that which is being investigated i.e auditory perception. Unfortunately, most measurements have a bearing on electrical performance, rather than auditory perception - a bit like doing an analysis of the fuel in order to tell us the car driving experience.

I would much rather judge a car's potential to match my expectation of what I want from it by listening to others driving experiences rather than looking at fuel analysis figures!

Audio and automobiles do have something in common - they both have a practical side and an enthusiast side - the practical side of the automobile crowd values cars for their ability to efficiently get the driver from point A to point B. The enthusiast side of the automobile crowd looks for cars to do more than just get a driver from point A to point B, such as is the car fun to drive, does the car have soft leather seats and so on. Nothing wrong with being an enthusiast.
 
In audio things are similar. The practical side values audio equipment on its ability to faithfully reproduce whatever is on the recording. The enthusiast side wants more than that, such as does the equipment add an additional layer (of lack of a better word) of enjoyment to the listening experience. Again there's nothing wrong with being an enthusiast. Just bear in mind that the end goals for each side are different.
 
So if having fancy cables and audio equipment made with a very expensive finish (solid aluminum face plates or 70 coats of hand rubbed varnish) makes for greater enjoyment than by all means go for it, just understand that these things really don't improve the overall fidelity of the system. So greater enjoyment to the enthusiast, yes. Truer fidelity, no.

 

[gregorio]

You mean measurements that have any correlation (never even mind causation - that would be the next step) to what is actually perceived? I don't consider that a "high standard" - I would consider it a basic requirement of any measurements i.e that they have a direct, proven relationship to that which is being investigated i.e auditory perception. Unfortunately, most measurements have a bearing on electrical performance, rather than auditory perception - a bit like doing an analysis of the fuel in order to tell us the car driving experience.

 
Ah, such a shame, just when I thought we might have a sensible, rational discussion, you go and say this! Look, it's quite simple, regardless of whether it maybe an anathema to some audiophiles:
 
Sound recording technology is fundamentally just the measurement/conversion of acoustic energy (frequency and amplitude), to electrical, then digital and back again. That's it, frequency and amplitude measurement/conversion, there is nothing else. How we perceive that frequency and amplitude data is a whole other kettle of fish, with one or two very crude exceptions, we cannot measure any of the multitude of human aural perceptions. As far as recording/playback technology is concerned, by definition, if we cannot measure it, we cannot record it or reproduce it and therefore it's completely irrelevant! As rather simple minded consumers we want to know if something is good but "good" is not a recording technology function, accurate or inaccurate measurement/conversion of frequency and amplitude is as far as it goes, anything outside that is nothing to do with sound recording or reproduction technology. For example, as far as recording and playback technology is concerned, music does not exist, there is just sound (frequency and amplitude), music as something which can be differentiated from sound is purely a human perception, it is NOT any definable or measurable quality, quantity or property of sound.
 
With this basic unquestionable axiom in mind. A USB DAC (for example) is by definition designed to operated optimally to a USB specification signal and a USB specification cable. And, a USB specification cable can be made for peanuts! One may decide to buy a USB cable for more than peanuts, on the grounds that it may provide more longevity, but buying one on the grounds that it exceeds USB specifications and therefore improves the fidelity of the output signal is nonsensical. Perception is a different matter, which doesn't necessarily have anything to do with fidelity (the accuracy of measurement/conversion), how good a piece of music is perceived to be is purely a function of the ability of those who created the music to manipulate the biases inherent in your perception. Likewise, a shiny new expensive cable can easily be perceived as good or better than before but again, this is a function of your biased perception, biases which the marketers of the shiny new cable seek to exploit, exactly the same in principle as the music creators do. In both cases this can't be measured and exists purely as a perception in your head rather than as a physical property of a recording or playback chain.
 
G

 

[mmerrill99]

You mean measurements that have any correlation (never even mind causation - that would be the next step) to what is actually perceived? I don't consider that a "high standard" - I would consider it a basic requirement of any measurements i.e that they have a direct, proven relationship to that which is being investigated i.e auditory perception. Unfortunately, most measurements have a bearing on electrical performance, rather than auditory perception - a bit like doing an analysis of the fuel in order to tell us the car driving experience.

Ah, such a shame, just when I thought we might have a sensible, rational discussion, you go and say this! Look, it's quite simple, regardless of whether it maybe an anathema to some audiophiles:
....
G

Yes, such a pity that you are not able to get beyond your own limited perspective of what you incorrectly interpret to be the meaning of & science behind auditory perception. But as you say, unless you do so, sensible, rational discussion is beyond you!

 

[ralphp@optonline]

Yes, such a pity that you are not able to get beyond your own limited perspective of what you incorrectly interpret to be the meaning of & science behind auditory perception. But as you say, unless you do so, sensible, rational discussion is beyond you!

You seem to have gotten everything just a little bit backwards. I suggest that you reread this entire thread and see if you can straighten yourself out.