Hi Chris,
The two sentences you quoted are referring to two different things.
The first sentence refers to the likelihood that under normal circumstances the circuit receiving the data will not mistake a 1 for a 0, or vice versa, despite the presence of noise that may be conducted in the cable.
The second sentence refers to the possibility that noise that may be conducted in the cable may find its way into D/A converter circuitry, causing jitter, or into other circuitry further downstream (including analog circuitry), where it may have audible consequences even though the data has been received correctly. Conceivably it may "find its way" via unintended circuit paths such as stray capacitances, grounds which behave in a less than ideal manner at frequencies that are contained in the noise, by radiation of RFI (as Kijanki mentioned), etc. And that could very conceivably occur to an audibly significant degree under normal circumstances, depending on the specific designs that are involved. And that kind of effect is the only way I can think of by which sonic differences could occur between reasonably well designed USB cables, when used in reasonably well designed asynchronous USB applications.
When I was drafting my post it occurred to me that those two statements might be conflated, when they were meant to refer to different things. Which is why I added the words "when that determination is made" at the end of the following sentence, although perhaps I should have added clarification that was more explicit:
-- Al
The two sentences you quoted are referring to two different things.
The first sentence refers to the likelihood that under normal circumstances the circuit receiving the data will not mistake a 1 for a 0, or vice versa, despite the presence of noise that may be conducted in the cable.
The second sentence refers to the possibility that noise that may be conducted in the cable may find its way into D/A converter circuitry, causing jitter, or into other circuitry further downstream (including analog circuitry), where it may have audible consequences even though the data has been received correctly. Conceivably it may "find its way" via unintended circuit paths such as stray capacitances, grounds which behave in a less than ideal manner at frequencies that are contained in the noise, by radiation of RFI (as Kijanki mentioned), etc. And that could very conceivably occur to an audibly significant degree under normal circumstances, depending on the specific designs that are involved. And that kind of effect is the only way I can think of by which sonic differences could occur between reasonably well designed USB cables, when used in reasonably well designed asynchronous USB applications.
When I was drafting my post it occurred to me that those two statements might be conflated, when they were meant to refer to different things. Which is why I added the words "when that determination is made" at the end of the following sentence, although perhaps I should have added clarification that was more explicit:
The receiving circuitry just has to determine which of the two signals in the differential pair is at a higher voltage and which is at a lower voltage than the other, during each bit interval. And noise that is present on both signals (i.e., common mode noise) will be ignored under any reasonable circumstances, when that determination is made.Regards,
-- Al