usb cables?

[adamdea]

3 hours ago, JanRSmit said:

So , to understand what you are saying, in the case of digital info, noise (which is always present) will not somehow interfere if it stays below a certain level. Then the questions i have:

How is this achieved in essence?

does the noise spectrum make a difference?

Is this true also for computer to dac communication?

How do i as enduser know the always present noise is not interfering? 

Taking this question at face value, the answer to your question is that noise in a digital infromation system does not (until it reaches a treshold level) interfere with the signal because it is a digital information system.

There is a very easy way to understand it which is to forget what you think you know and just consider everyday numerical and symbolic information like numbers on a page.

 

Write the number 1 on a piece of paper. with a pencil. Show it to someone and ask them what number is on the paper (from 0 to 10).

Try making the line slightly wiggly and vary its length . How wiggly/ short/long  does the line have to be before the reader is unable to identify the number as a 1.

Repeat the experiment asking the reader to identify whether the shape you have drawn on the piece of paper is a 0 or a 1.

How does this affect the threshold of wiggliness/length?

 

The information content of a symbol (number/ digital signal) remains the same despite large amounts of distortion or variation in the carrier medium (pencil marking/signal voltage). There is no particualr reason why symbolically encoded information SHOULD be affected by variations in the carrier medium (wiggliness/noise) provided that the symbol can be read. Where there are only two possible values (o and 1) you can have one hell of a lot of noise without affecting the ability of the reader to identify the 0s and 1s.

 

Provided that you have correctly read the data you have a complete record of the song. There is no further information required for reproduction of the song. How can changing usb cables make any difference provided that the data can be read? There are a number of ways of verifying that information is perfectly transmitted. It can be done by sending DTS encoded files, and some dacs have diagnostic files to check (eg an Mdac). The major purpose in the diagnositc files is to check for unexpected resampling /dsp in your computer, because the usb cables will transmit the data fine. If you get a sum wrong, it is probably not because of the pencil you use.

This is very easy to understand as long as you forget all the audiophile bull. Interesting factoid: Shannon's proof of the sampling theorem is contained within a paper entitled "Communication in the Presence of Noise"

 

 

[adamdea]

57 minutes ago, Ralf11 said:

 

I'll paraphrase what Peter said:

 

 

So... if you have isolated the DAC from all 3 possibilities of noise injection different USB cables (that meet the spec.) will not make a difference.

 

Differences are perceived either because of confirmation bias or because they actually exist due to lack of isolation.  Double blinded and properly conducted listening tests would tell you if the former was the reason, but are rarely done.  AND, it may be easier to buy an inexpensive isolation device than to conduct the test.

leaving aside cables which cut off the ground and/or 5v, it is worth bearing in mind that most cables contain conductors which are generally made of metals chosen for their property of conducting electricity. So the only thing which any of these cables can do with noise is to conduct it. This will not get any better by making the conductors out of silver rather than copper, or having a fancy dieletric or giving the conductors a much bigger diameter. Compare eg various audioquest cables at different price points. Supposing that there is noise coming from the computer source and the dac is sufficiently badly designed to allow this to reach its analogue output, thus essentially negating its purpose as a digital audio device. How will a fancy cable help by conducting the noise slightly better? Just saying.

[adamdea]

6 hours ago, sandyk said:

[I.M.E.  Any USB cable >3M long used without Regeneration will reduce SQ to some degree , in part due to RF/EMI issues,] and in some  cases the connected USB device will not function correctly, or perhaps even be identified due to excessive voltage drop with the incoming +5V rail.  This is governed by the size of the conductors stipulated in the USB standards with many cables using thinner conductors than permitted.

 

(The 2.0 specification limits the length of a cable between USB 2.0 devices (Full Speed or Hi-Speed) to 5 meters (or about 16 feet and 5 inches).

Well chase my Aunt Fanny up a gum tree, Sandy, if we ignore the bit in square brackets you've just posted something that is not only not batshit crazy but actually correct. Truly these are the End Days

[adamdea]

4 hours ago, adamdea said:

Well chase my Aunt Fanny up a gum tree, Sandy, if we ignore the bit in square brackets you've just posted something that is not only not batshit crazy but actually correct. Truly these are the End Days

 

9 minutes ago, mansr said:

The USB 2.0 standard does not specify wire gauge for any of the conductors.

Dammit Mans, even this you take away from me.