USB audio transmission isn’t bit true

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2 hours ago, tmtomh said:

As @mansr and others have patiently tried to explain, this Rankin statement is what we might call "just close enough to the truth to be misleading." I say that because the frequency of USB/digital transmission errors - how often they occur and what the sonic consequences of them will be - must be taken into account. And this is something you have steadfastly refused to do.

 

(And no, I am not trying to be mean by saying your statements are thoughtless - rather, I'm observing the irony that you seek to make people think while at the same time amply demonstrating that you yourself are unwilling to reconsider the propositions with which you start your threads.)

 

Beerandmusic does not 'get'  frequency, rate, and similar realities.  It's not just that the math is hard, but the connection between math and physical reality is not there.  He is not alone of course and the Audiophile marketing machine uses this to their advantage.  Heck, even folks like John Atkinson appear to be fundamentally confused by frequency and the like when they opine about "transients", "leading edge arising out of blackness" and how they affect the rest of the signal, etc.

 

Now that I think about it, beerandmusic and John Atkinson are not that far apart in how they conceptualize signal...

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16 minutes ago, tmtomh said:

 

 

I believe Amir over at audiosciencereview did USB cable tests and found the same thing - length was the only fact that consistently correlated with signal quality. He got equal or better results with generic/cheapo cables compared with expensive/audiophile ones when comparing cables of the same, short or medium length.

 

Amir, mansr, JohnSwenson, fill_in_the_blank - they are all confirming (or if you prefer, "discovering") exactly what the computer/networking industry has been saying all along.

 

Yet, in Audiophiledom we always need to speculate about the unknown, and of course we are continually sold various decrapifers and speculations that allegedly fix the unknown...

 

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18 minutes ago, JohnSwenson said:

There actually IS a difference. Music uses isochronous transmission which has NO error correction. Most other forms of data use transmission protocols which DO have error correction, thus transmission errors get corrected so the end user never sees an error. With music there is no correction so transmission errors DO show up at the DAC.

 

Per my previous post transmission errors are very rare with shorter cables, but do happen a LOT with longer cables.

 

So while in some sense data is data, how music data gets sent over USB is very different.

 

John S.

 

What is the rate of these errors, in typical use case scenarios (i.e. computer to DAC, streamer to DAC, and shorter cables of 3 feet or less)?  The answer is "very rare" as you say but how is that quantified?

 

 

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2 hours ago, Superdad said:

 

Using a USB protocol analyzer.  John and I each have one from Teledyne Lecroy.

 

Of course this whole conversation of bit errors has little to do with transmitted USB signal integrity--and its effect on the PHY of a DAC's USB input (ground-plane noise/bounce and packet-data noise), which ultimately affects the DAC's master clock and is the real reason why  people hear differences with USB cables and regenerators.  

 

Is the physical layer (the "analog" foundation of any "digital" signal for folks who don't know) noise to which you refer here, measurable?  Is the effect that this noise has on the master DAC's clock correlated in measurements if not directly measured?  If so, what tool do you use for this job?

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17 minutes ago, OE333 said:

In our new SDV3100HV DAC we constantly monitor and analyze the USB transmission quality. It would be easy to display the results and give the user a feedback about transmission quality. That could give some information about cable or noise problems etc.

So perhaps in the next firmware version we should include this feature....

 

 

That would be very cool and oh-so anti "audiophile", in that audiophiledom loves to talk endlessly about their personal USB foibles when the evidence (what there is) points in other directions.

 

The only other manufacture I know of who provide any end user USB quality feedback at all is Schiit (perhaps there are others) with their "buy better gear light", and it is just a light - very minimal.