High End USB Cables - Real or Fantasy?

+1 on a serial bus signal in a USB is an analogue differential signal that when decoded provides the logical bits of a data frame..

However can't agree about asynchronous mode is less dependent on the USB cable. In fact it's the complete opposite. In asynchronous mode which uses isochronous USB transfer, there is no flow control or frame retry. A poor cable or a cable working on the edge of its spec will more likely corrupt a frame and the data is gone forever.. There is no retry.. This is the same as SPDIF or using UDP on Ethernet. 

Simon

Simon - almost every time I read one of your posts, I wish I were a geek, but i am just not into it enough to ever become one.  I am not tech incompetent, but boy do you make me feel dumb!

Makes logical sense to me (i.e. if the V1 calls the data but there is no way of checking whether all of the data is sent then the it can only work with what it receives/has already).

I guess there is also  the issue of jitter and whether the cable introduces this and if so the effect this has on data loss....

So, my understanding is that the perfect cable is one that does not alter the data stream content caused by EMI.

Of course, in reality the decision is about choosing which cable minimises this and accepting the affect it has on the data stream in order to achieve this.

Of course, the system has to be capable of showing the difference.  I guess most Naim kit would.

I do love a good puzzle

J

Jude, I think you more or less sum it up.. However i suggest you don't get wrapped up about jitter.. This is transport jitter.. The same as for SPDIF jitter.. It's not sampleclock jitter. The data is sent in frame bursts anyway.. It's not a smooth bit stream of PCM. In the old days the DAC clock was often derived from the transport clock directly and so transport jitter could cause all sorts of upsets. These days DACs use there own precision clocks or at worse a phased lock loop clock, and the data is buffered as the transport frames are read and decoded. Therefore these days transport clock jitter, like SPDIF transport jitter , is more likely to let itself be known via EMI and indirect side effects rather than directly impacting the DAC clock.

Simon

PS Dr Mark.. Let your inner geek surface 

http://www.naimaudio.com/sites...-usb_mwp_jan13_0.pdf

Well, the Vertere Acoustics Pulse D-Fi USB A/B cable arrived this morning and has been duly installed to replace the unbranded, shielded cable that I have been using (it's a spare cable that originally came with a wifi router).

I can confirm that the system definitely sounds different when the unbranded cable is replaced with the posh one.  Rhythm, timing, bass quality and musical involvement are significantly different.  It was obvious within 2-3 seconds of hearing the first song (an Eric Bibb track from his album Painting Signs) and wasn't subtle.

Why is it different?  What is the technical explanation?  Despite Simon's best, informed and technically eloquent efforts to explain such things, I can confidently assure you that I have no idea.  Absolutely none.

But one cable allows the system to play wonderfully engaging music, while with the other I hear a slightly ponderous, plodding, slow hi-fi that tries but fails to play music.

More to come as I dig into this a little further.

Best regards, FT 

FT it's magic 

a lot of that in audio

Well, replaced my $10 Nexxtech 1m High-Speed data USB cable with a $75 1m Straight wire USB cable and the difference is akin to adding a NAIM Power Supply to any Naim component.  There is a difference and must be down to the quality of the wire used. 

Gotta love this snake oil - http://www.hifiart.se/index.ph...tID=4&prodID=224

"Cables can not actively improve a recording´s sound, of course, but they can adversely affect it to varying degrees. The key is to make a cable as neutral as possible when it comes to conveying information."

For people that don't understand the difference between a digital and analogue cable this must sound really scientific. LOL. In case people are wondering, when it comes to digital cables there is no such thing as 'neutral' - they either work or they don't - end of story!

Oh dear another bits-are-bits adept. :-(

Aleg, exactly, when it comes to digital cables, the statement it either works or it doesn't is just sooo mis informed... It simply isn't the case LOL ... After all 'digital' cables carry an analogue electrical or light signal. Good old physical layer in the OSI 7 layer model if some one needs an introduction. If this wasn't the case we mostly wouldn't need many of the techniques and protocols of digital data transmission to ensure bits remain bits.... Even in our humble SPDIF framing protocol. And that's not even at looking intermodulation and EMI from the physical signal.

Simon

Interesting, Simon.

So please tell me what the difference is between the bits that leave the application layer of the server and the bits that finally end up in the application layer of the client (renderer if you will).

As I am sure you are aware, the layer above the transport layer (the data-link layer) deals with any errors that may occur during the transmission and fixes them.

In a working system digital data transmission is guaranteed error free and lossless. Please explain to me how it could be otherwise.

If I copy a music file from one disk to another over a network 1,000,000's of times it will never degrade nor gain nor lose one bit of information.

Aleg - this is such a tiring argument, please explain how it is ever possible that bits-are not-bits.

Let's go Star Trek.  Bones detests the transporter because it scrambles all his molecules and he (rightly) knows that it doesn't always work. Now the transporter takes a 'static' object, disintegrates it and then reassembles it in the same 'static' form. Music is a 'moving' object that can't be reassembled at one point in isolation. How well does the transporter now cope? Star Trek Generations gives an answer. If you haven't seen it, well not everyone gets through.

Incidentally you cannot copy a file millions of times without corruption. It will lose bits, it will slowly corrupt, it will ultimately fail. There is no such thing as a perfect copy, not in computers, not anywhere. Almost perfect? yes,good enough? yes, often, but perfect? no.

The tiring argument is actually the flat-earth approach of bits are bits. Molecules are molecules and yet a collection of the same H2O ones can be in a solid, liquid or gaseous state. Does that help any?

Andy 

Andy,

In the digital world there is absolutely no degradation when you copy files. If this wasn't the case then computers would never work at all.

Honestly - copy a file (it doesn't matter what kind) from one disk to another and compare the difference (unix has a great command called 'diff' to do this) - they will be identical.

Do it 100 times - they will be identical.

Do it 1000, 10000, 100000, 1000000 times ad nauseam and as long is your computer is working they wil always be identical.

This is guaranteed.

Digital information transfer is a fundamentally different technology to analogue signal transfer (which will degrade each time) but digital cable manufacturers will play on people lack of understanding of this to sell unnecessarily expensive cables.

WRT static vs moving - A computer file is a static object and it is copied as such when it transfers from one place to another. It is the job of the streamer/renderer to convert that static data into time dependant music stream, but this only happens once the data has been statically moved into its buffer (basically a very small disk) and so the transport medium is essentially irrelevant (as long as it can keep the buffer full.

Jude - it does - that is a key part of the TCP protocol. Please see here

https://en.wikipedia.org/wiki/...ion_Control_Protocol

Just imagine for one minute that network traffic did not have complete error and data integrity checking built in. Would you use it to shop online?

The USB audio profile  has no error checking if you are not using it sensibly or if you have old equipment. But you're an audiophile - why would you be using USB audio in that way?

Conrad,

I think you are missing the point. Shopping online is miniscule amounts of static data. Error checking can take its time. An donly when its happy does it need to say 'finished'.  A music file is a relatively large amount of data and the timing between reading the consecutive bits is critical to reassembling a correct waveform. Error checking software counts the actual 1s and 0s, it doesn't check the timescale (see the Naim white paper on the DAC V1. Far more compelling than a Wikpedia entry base purely on limited theoretical knowledge).

Andy

The CD-technology also causes bit errors, bad sound and a lot of confusion among listeners. Somtimes a CD disc may sound OK, but more frequently the same disc sounds bad. There is, however, ways to improve the CD sound.

The most destructive CD error seem to be rather unknown and related to poor pick-up tracking and bad centered discs. Since the tracks on a CD are of microscopic size, there is very little chance there is a perfectly centered disc. However, since the turntable must be skewing for the same physical reason, try to place the CD at an angle to the turntable that reduces the resulting skewing angle. Testing eight different angels, one of them should result in a big improvement in sound. The bass sound becomes transparent and 3D-like, the mid and high frequencies come to live as well. Put a mark on the CD corresponding to a mark on the turntable for the best angle. Using headphones the procedure may take a minute or so. I've improved the sound of hundreds of CD's that way, and it worked significantly well in 99 of 100 cases.

A CD now sounds more like vinyl, especially after a few other modifications, such as painting the inner and outer edges of the disc and the CD-player's interior with a laser-absorbing color that can be purchased, green if the laser is red. I mixed my own green color close to that of the purchased and it worked well. Black is not as effective as the inverted color. I also made the pick-up suspension less stiff. Lots of experimenting but worth it. The terrible sound of a cheap portable CD-player from the early 90's was finally converted into something relaxing that proved that CD technology as such keeps its promises, but the physical reality is certainly a more complex affair.

More about CD error correction,

http://www.blantonemusic.com/red_book_standard.html

After trying several more or less "audiophie grade" USB cables and standard USB cables all I can say is that all of them sound different. I tried it with DAC-V1 and laptop (Windows/Wasapi). Of course one can speculate an endless time if this is possible and why it is so, but I prefer enjoying my music in the meantime. I ended up wit a Chord USB Silver Plus which I liked better than several Audioquest (moderate costs to crazy costs) and Supra (good VFM, too). I would not be too suprised if we would see an "official" Naim USB cable in the future... This would probably end all discussions about USB cables. We had the same regarding power cables before the "offcial" Powerline showed up Always the same...

My two cents, based on listening, not "science":

I have tried Belkin (cheap), Audioquest Carbon (expensive), and Vertere (somewhat cheaper than Carbon) USB cables into the V1.  They all sound different, and I prefer the Belkin to the AQ.  The winner, however, by a considerable margin, is the Vertere--Touraj still has that magic touch.

USB cables are also electrical connections, if people only look at 'bits' the are completely missing the point of differences between digital interconnects.

All digital IC I have used sound differently, be it SPDIF or USB.

cheers

Aleg