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USB cable makes a difference shock!

Yes absolutely, don't answer my question with a question.... i'll say it again incase you didn't see it: what if the deleterious effect is affecting other kit at attached ends?
 
No, no at all, my question has nothing to do with dB rating....

The test result shows the D-A conversion shows measurable differences @-140db+
My question is what are the differences causing in the D-D environment? this isn't remotely the same question.
 
Maybe out of the human hearing range, but what if the deleterious effect is affecting other kit at attached ends?

This test shows that the difference in the cables is measurable but below the human hearing threshold. Can you show any test results to show that the difference is audibly affecting other attached kit? If not, yours is a rhetorical question only in the context of this test.
 
No, no at all, my question has nothing to do with dB rating....

The test result shows the D-A conversion shows measurable differences @-140db+
My question is what are the differences causing in the D-D environment? this isn't remotely the same question.

It has everything to do with dB

If we assume that the output voltage of a DAC is 2V then the noise at -140dB is (at most)

0.000000000000002 Volts

or

0.2 pV (that is pico which comes after milli, micro and nano)

Do you think that would be audible (hint - anything below -60 dB is inaudible to the average person) or could possibly have any effect elsewhere?


If you want to use a digital argument (which really doesn't apply in that test but we'll play along for shits and giggles)

USB 1.0 uses a signal differential of roughly 3v to represent a 1/0 therefore using a 3v reference -140dB would equal.....

0.000000000000003 Volts

or

0.3 pV

Even at the highest bandwidth and specific signalling USB 2.0 looks for a differential voltage of 400mV that is 0.4 Volts

Do you think that either 0.000000003 or 0.0000000004 mV could cause any spurious effects?
 
Thanks for the detailed maths on db ratio. I was aking what is happening in the digital to digital domain not in the analog result.
 


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