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I am currently reading about Digital-Analog-Converters in a magazine. In one section about connecting an iPod, it says that the sound via a USB cable such as the one from Audioquests Cinnamon is significantly smoother and more velvety compared to the official USB cable from Apple.

Also, a standard USB cable: In the description of Audioquest "Coffee", they are claiming that there is a huge difference. And they cost about 280€! Or their "Diamond" version costs about 550€! Here is some review, again claiming that there is a difference. Here is another review. And here another one.

How can that be? The signals which go through the cable are digital. How can there be any difference?


(Just for reference, I also asked the same question on AVP.SE with similar answers.)

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You should return that book. –  Ian C. Nov 8 '13 at 17:51

3 Answers 3

up vote 3 down vote accepted

As far as I understand it, cable jitter is a possibility so a USB cable with less jitter is better.

The question seems to be: does a standard USB cable have that much jitter that you need a expensive usb cable?

So far I think most reviews have taken a subjective point of view. Here are some actual measurements:

…so it seems there are no differences between the USB cables, but people are willing to pay the prices so somebody is going to offer.

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+1 Nice links. I don't see how the cable jitter mentioned in the first link would actually happen unless you're using a dedicated master clock source. Likely the OP is just using the built in clock on his DAC. If this is the case, at no point will timing info need to be transmitted over a USB cable. –  Dean Nov 8 '13 at 19:37

The digital path, as long as it is good enough to work, will not make any difference.

A long or poorly shielded USB cable can cause noise problems on the power supply side of the attached device. I have seen this on electronic test equipment using long and very thin USB cables. This has manifested itself as a 50Hz buzz on the 5V line which is then picked up by the ADC in the device. I would imagine it would be the same for any sound card.

Most cables are however fine.

The particular articles linked to sound like the usual made up audiophile rubbish though.

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Yea, but if some data is crippled along the cable, you should get jittering or similar effects in the sound output, not any distortions like that it is less smooth or less velvety or so. I really don't get it. Why are there cables for 600€? That doesn't make any sense. Why are so much people claiming that there is a significant difference? (I understand that if its analog, it can make a difference. But that's not the case here.) –  Albert Nov 8 '13 at 15:57
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It's because some people have more money than sense. –  Cybergibbons Nov 8 '13 at 16:00
    
At risk of taking this thread off-topic, I believe it's been scientifically proven that people's perception of an experience is heavily influenced by their expectations. Whether you are using premium cables, expensive wine, vodka - in double blind tests, people will statistically enjoy more something for which they paid more. Rather than turn this into a psychology debate - let's focus more on if there's a problem here than setting up straw men like "audiophiles" for name calling. –  bmike Nov 8 '13 at 16:50

If we're talking about 30-pin iPod connectors (which we seem to be, based on the link you provided), there is an analog signal for audio—line out is carried on pins 3 and 4 if pin 11 is grounded.

(That said, I'll wholeheartedly commit to the prospect that multi-100-euro cables are almost certainly substantially overpriced.)

http://pinouts.ru/PortableDevices/ipod_pinout.shtml

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Oh, that is interesting! But the magazine was testing DACs. That doesn't make sense then. –  Albert Nov 9 '13 at 8:32

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