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USB CABLE

They aren’t better not in terms of sound quality, they measure just as well and have a smart case.
I usually advise that the money would be better spent on components that actually bring an improvement.
Keith
 
Greyandy said:
He’s probably too busy trying to work out how to answer my question on what objective proof he has about his expensive DAC’s being better than a more humanly priced one…
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I think Keith has all the answers...if we choose not to accept these answers..its our fault..Keith doesn't need to work anything out, he knows it all...you know what, he might be right? He never deviates..no muddled thinking there..clear and concise..that's strong juju...of course he is wrong..but with that strong juju, wrongness can seem like rightness! Keith is the voodoo king of hifi...
 
Purité Audio said:
They aren’t better not in terms of sound quality, they measure just as well and have a smart case.
I usually advise that the money would be better spent on components that actually bring an improvement.
Keith
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Sorry but I can't navigate my way through the double negatives in this... Could you re-phrase please?
 
zarniwoop said:
No. I predict that if he repeated the test multiple times with the same cable and using the same alignment technique he would get some with less audible difference and some with more. It's all about the clock in the ADC and where it is in its cycle when the recording starts.
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So basically the differences he is measuring are as a result inherent inconsistencies in the whole DAC/ADC system and not the cable?
If this is the case then it would seem that a test method is needed that eliminates these components.
His blind AB test results do suggest that there is a difference but of course it's only a sample of one.
 
Greyandy said:
Sorry but I can't navigate my way through the double negatives in this... Could you re-phrase please?
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With an expensive dac you are paying for perhaps some interesting features and a smart case, remote milled from solid, pride of ownership, there is no sound quality improvement over one of the less expensive dacs we represent.
I have verified this with level matched unsighted comparisons.
Keith
 
zarniwoop said:
If I've understood correctly, he passed a digital signal through a USB cable to a DAC and then took the analogue from there through an ADC and recorded it. He repeated for each cable and aligned the recordings by identifying the same sample in each. The problem is that there is no "same sample" to align. The ADC will sample the analogue at slightly different places every time, so his alignment is off.
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Yes, exactly. His theory is OK in principle if he could record two analogue versions of the track via different cables, and slide them continuously against each other and subtract when they aligned. There would be a fairly deep (but not zero I think) null.

However once he samples and digitises the analogue DAC output, the he can only align them at specific samples. The sampling clock will not align with the audio waveform unless you take some specific measures. So he will inevitably see a non-null comparison as a result of the method.

When he tested the method by recording one cable twice and tried comparing these, it showed a non-null comparison with the same cable as a result of the test method problem, as I expected. But he proceeded to blame the cable for this rather consider it might have been his method. He is wrong to conclude what he concluded. There is no valid conclusion here other than his method may have a defect he hasn't accounted for well enough. I actually think it's does have ... not may have ... but I will listen to argument.

EDIT: he would do better if he took the audio and up-sampled it x8 then compared. But he would still be limited to nulling at restricted points on the audio waveform.
 
Purité Audio said:
With an expensive dac you are paying for perhaps some interesting features and a smart case, remote milled from solid, pride of ownership, there is no sound quality improvement over one of the less expensive dacs we represent.
I have verified this with level matched unsighted comparisons.
Keith
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So you mean that you sell your gear based purely on Expectational Bias? So how is this acceptable with DAC's and not USB cables?
 
John Phillips said:
Yes, exactly. His theory is OK in principle if he could record two analogue versions of the track via different cables, and slide them continuously against each other and subtract when they aligned. There would be a fairly deep (but not zero I think) null.

However once he samples and digitises the analogue DAC output, the he can only align them at specific samples. The sampling clock will not align with the audio waveform unless you take some specific measures. So he will inevitably see a non-null comparison as a result of the method.

When he tested the method by recording one cable twice and tried comparing these, it showed a non-null comparison with the same cable as a result of the test method problem, as I expected. But he proceeded to blame the cable for this rather consider it might have been his method. He is wrong to conclude what he concluded. There is no valid conclusion here other than his method may have a defect he hasn't accounted for well enough. I actually think it's does have ... not may have ... but I will listen to argument.
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I guess one way of establishing the variance in the whole system would be to carry out a number of tests on each cable to establish the level of variance for a single cable tested multiple times and then compare this to the results from different cables.
 
Greyandy said:
I guess one way of establishing the variance in the whole system would be to carry out a number of tests on each cable to establish the level of variance for a single cable tested multiple times and then compare this to the results from different cables.
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An interesting thought but IMHO much better would be to synchronise the sampling clock on his ADC to the conversion clock on his DAC. As is done in audio studios, although it may not be possible with his kit. I think that would go in the direction of curing the problem rather than applying a sticking plaster to it.
 
Greyandy said:
So you mean that you sell your gear based purely on Expectational Bias? So how is this acceptable with DAC's and not USB cables?
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I just represent really fine measuring equipment, Weiss and Mola both measure excellently as does RME, the differences are mainly the construction and materials of the case and price of course.
Keith
 
Purité Audio said:
I just represent really fine measuring equipment, Weiss and Mola both measure excellently as does RME, the differences are mainly the construction and materials of the case and price of course.
Keith
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So you are paying for that warm feeling that 'more expensive must be better'. Hmmm... somewhat ad odds with your thoughts on expensive USB cables...
 
John Phillips said:
An interesting thought but IMHO much better would be to synchronise the sampling clock on his ADC to the conversion clock on his DAC. As is done in audio studios, although it may not be possible with his kit. I think that would go in the direction of curing the problem rather than applying a sticking plaster to it.
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This is interesting. Looks like we may be getting close to a reliable test method.
 
Greyandy said:
Sorry but I can't navigate my way through the double negatives in this... Could you re-phrase please?
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Funny thing is, there is no double negative I can see. Keith makes it clear that his more expensive dacs will sound the same as his cheaper. You are just experiencing cognitive dissonance. How is this possible? No one could possibly say that. Yes they can.
It is possible to value a component for something other than sound quality.
 
adamdea said:
Funny thing is, there is no double negative I can see. Keith makes it clear that his more expensive dacs will sound the same as his cheaper. You are just experiencing cognitive dissonance. How is this possible? No one could possibly say that. Yes they can.
It is possible to value a component for something other than sound quality.
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Unless, according to some, it's a USB cable.
 
Greyandy said:
So you are paying for that warm feeling that 'more expensive must be better'. Hmmm... somewhat ad odds with your thoughts on expensive USB cables...
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There is a ‘pride of ownership’ component to any purchase choice,I simply make it clear that the more expensive dac will not improve the sound quality you experience.
Keith
 
Greyandy said:
This is interesting. Looks like we may be getting close to a reliable test method.
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Maybe not yet. As I wrote, it's a step in the right direction but the astute will see that if I have got this right it avoids the two clocks producing sample points that differ from cable to cable. However synchronizing the clocks will, on its own, just lock the sample points at some maybe not yet constant enough time offset from each other. This does not quite ensure yet that they exactly coincide in time - which is a core requirement of such a test.

It's possibly a layer of the onion peeled. But there are probably more to go. It's always important to understand the quality of the onion underneath and not stop peeling because you can't see what's still wrong. And you also need to understand exactly what the onion underneath is telling you, and if that's relevant or not.

However none of this may be important to the (in the best sense) amateur audio enthusiast and what he/she chooses to buy and how he/she justifies that choice.
 
John Phillips said:
Maybe not yet. As I wrote, it's a step in the right direction but the astute will see that if I have got this right it avoids the two clocks producing sample points that differ from cable to cable. However synchronizing the clocks will, on its own, just lock the sample points at some maybe not yet constant enough time offset from each other. This does not quite ensure yet that they exactly coincide in time - which is a core requirement of such a test.

It's possibly a layer of the onion peeled. But there are probably more to go. It's always important to understand the quality of the onion underneath and not stop peeling because you can't see what's still wrong. And you also need to understand exactly what the onion underneath is telling you, and if that's relevant or not.

However none of this may be important to the (in the best sense) amateur audio enthusiast and what he/she chooses to buy and how he/she justifies that choice.
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So I guess that as we are saying that we can't yet prove there is no difference between USB cables, by the same token we are not yet able to prove that there is. Hence my often pilloried statement that the 'jury is still out'!
 
No we aren’t saying that at all , the methodology of that video is fatally flawed, what we have are electrical measurements and unsighted comparisons .
 
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