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PostPosted: January 11th, 2019, 4:14 pm 
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Joined: January 15th, 2015, 7:19 am
Posts: 842
Location: Baltimore MD
While repairing that music server I snagged a couple of premium USB cables
One $300 and one north of $2k
I compared with what I have been using a $5 cable from micro center. It’s blue in color

I chose a cut I’m familiar with and went back a forth between all three cables four times.
I really could hear no difference between any of them.


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PostPosted: January 11th, 2019, 5:20 pm 
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I believe your observations are correct, but that does not mean USB cables do not make a difference. If you are using a standard USB port on a laptop or PC, you will not hear any differences because, computer power supplies are very noisy and on top of that the standard USB ports do not have a dedicated clock generator. Once you have a good USB port on the computer like SoTM, you will hear the difference USB cables make. SoTM, Rendu etc have dedicated crystals for clock generation and they use quite linear power supplies.

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Shashi


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PostPosted: January 11th, 2019, 6:13 pm 
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With the frequencies involved in USB2 I would not be surprised if poorly constructed cables caused transmission problems. What I don't know is how those problems would manifest themselves. Also as Shashi said there may be other parts of the chain that swamp out the cable effects. Things get touchy in the GHz range.


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PostPosted: January 11th, 2019, 10:33 pm 
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I am using a Raspberry Pi for a server and my USB receiver has an isolated power supply. Why would anybody not use an isolated USB power supply is not hifi


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PostPosted: January 12th, 2019, 10:14 am 
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Joined: February 19th, 2017, 9:43 am
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If the bits get from the source to the destination without error, there will be no difference in the sound no matter how much you spend on a cable or how pretty it is to look at. If there are errors, you'll know it. Errors will not produce a specific type of coloration other than it sounds bad. Digital ain't like analog. Analog signals can be affected in particular ways based on cables. Digital errors are random and will generally destroy the signal to varying degrees depending on the bit error rate.


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PostPosted: January 12th, 2019, 11:41 am 
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This thread was started just for you Dave since I know how strongly you feel about this. I remained open even though in my brain I knew you were right. But I usually go with my heart when listening. I had to hear it for myself in my system and this was a chance to do just that. Now my brain and heart are insync with this matter


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PostPosted: January 12th, 2019, 5:29 pm 
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Joined: February 19th, 2017, 9:43 am
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That's always a good thing.


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PostPosted: January 12th, 2019, 5:52 pm 
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Joined: February 28th, 2013, 3:31 pm
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Take all those USB cables to Charlie P's house and you'll hear differences between them, and his. He's in Annapolis.

We didn't compare any digital cables when Dave R was last there, but did compare some for Tom P and Dave B recently. They were s/pdif that day, not USB, but the differences were obvious to everyone.


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PostPosted: January 12th, 2019, 6:23 pm 
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First, a caveat. I am by no means an expert on digital audio transfer protocols. At Charlie's we were auditioning SPDIF cables, not USB. I definitely heard a significant difference in the cables but have no idea of the mechanism that caused those differences.

There is a difference in the mechanisms of data transfer with SPDIF and USB. As I understand, in SPDIF the clock signal is carried internally on the signal in the form of a biphase mark code. In USB the data is transferred with three methods, isochronous, interrupt and control. The audio data uses the isochronous method, interrupt handles actions such as muting, and control is for operations such as device capability inquiries. USB does not rely on an imbedded clock in the data stream.

Beyond that I cannot comment on differences in the two but the general consensus is that USB results in more controlled transfers. Don't quote me on that. If that is true it MAY be that the SPDIF (or AES/EBU which is essentially the same thing with different impedances and methods specified for the connections) is more sensitive to cables than USB. I don't know. Currently all my digital audio travels aver USB connections. If you want to get into the weeds, here are two references you might find interesting.

https://en.wikipedia.org/wiki/Different ... r_encoding

https://www.xmos.com/developer/download ... 1.0%29.pdf


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PostPosted: January 18th, 2019, 1:18 pm 
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Here is a link to an interesting article on USB cables. Although it concentrates of USB 3 which has much tougher requirements than USB 2 which is used in most audio devices it still highlights the problems encountered when frequencies go up.

https://www.connectortips.com/stretchin ... nd-cables/


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