Effect of cables on digital *quality*

SteveR750

Well-known member
I have just been reading some comments on another forum that will remain nameless as it raises an interesting question; but fails to answer it, IT just IS - long live the flat earthers huh.

So, can a cable transmitting digital data really have an influence on the final converted analogue sound quality? If so, then do I need to choose my wireless re-router carefully, should I make sure that PC has quality components and internal wiring, or is it really some kind of mass hypnosis / hysteria that causes us to believe we can hear (or not) things?
 

daveh75

Well-known member
canofworms1.jpg
 

Gort1951

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I bought a £50 USB cable after reading a 5 star review.

The pictures transfered from my digital camera are far better.

There are more colors, details I couldn't notice before, the images are sharper and it even transfers the images in nearly half the amount of time than my old cable.

It's money well spent and I threw the old cable in the bin.
 

SteveR750

Well-known member
I can understand why a better cable might transfer data faster. The OP is not asking does it exist, simply why?? Its a scientific question, not a subjective / philosophical one so am more interested in what measurable test data there is, not what people see/hear.
 

Thaiman

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I was "obssesed" with WHY did I? or Shoud I? for a while and I thought it get in the way of my hobby which is enjoy music on a good sounding system (regardless of how they do it!)
 

nads

Well-known member
idc:
Here is QEDs take on why its HDMI cables transfer digital data better than other cables;

http://www.qed.co.uk/1/news/hdmi_explained.htm

Their argument is basically build it better with higher tolerances exceeding basic specifications and there will be fewer errors to correct in the data transmitted, so better sound.

forget the HDMI what about the SATA cable from you hard drive to the mother board? should that be upgraded?
 

idc

Well-known member
nads:idc:

Here is QEDs take on why its HDMI cables transfer digital data better than other cables;

http://www.qed.co.uk/1/news/hdmi_explained.htm

Their argument is basically build it better with higher tolerances exceeding basic specifications and there will be fewer errors to correct in the data transmitted, so better sound.

forget the HDMI what about the SATA cable from you hard drive to the mother board? should that be upgraded?

My first ever post on this forum was asking about whether music files and the hard drive and PC makes a difference to sound quality with using itunes and an ipod. The answer was no, a music file is just that and sq effects only happen outwith the PC. I repeated that a while ago, to which Andrew Everard stepped in and said that that is not the case and suggested some review of the musicality of PCs was coming. So maybe there will be a market for upgraded SATA cables to come!
 

SteveR750

Well-known member
idc:
Here is QEDs take on why its HDMI cables transfer digital data better than other cables;

http://www.qed.co.uk/1/news/hdmi_explained.htm

Their argument is basically build it better with higher tolerances exceeding basic specifications and there will be fewer errors to correct in the data transmitted, so better sound.

Well in some ways my question is slightly rhetorical, as I can understand that any data loss potentally degrades the final sound quality. I'm just puzzled why a conductor would lose data, I'm genuinely interested as I really don't unerstand the science of digital data transmission. The QED article is helpful thanks! I guess at the ed of the day its an electrical signal of varying voltage and current so its subject to the ame constraints as a conventional analogue audio signal.
 

idc

Well-known member
One area of cable manufacturing that is generally agreed upon is that the length of the cable is important. The longer the cable the greater the problems with signal transfer. For example USB cables reach their tolerances at about 5 meters.

So the argument is that below 5 meters there should be no problem. That works if you imagine a graph of sound over cable length which curves up, so initially it stays low and flat and then it curves up over 5 meters as transmission problems kick in. But imagine a curve which is rising from the very start and is more linear. After 5 meters the problems are obvious to all, but before 5 meters there is still the start of signal transmission degredation. It is not great, but it is still there.

That is my theory as to why digital cables can sound different and why some do not notice it and others do.

(I am not a scientist and please see the disclaimer in my bio!)
 
A

Anonymous

Guest
The cable makes no difference as long as it is designed around the USB standard and is not faulty.

The data transmission rates of streaming audio through a USB or S/PDIF cable, even at 24bit and 96kHz (ie 2 x 24 x 96,000 ~ 5MBit/s), are completely trivial compared to the 100 MBit/s that an £1 ethernet cable can push through. USB supports up to 480MBit/s since 2001. To put some more numbers around this; the current (2001) Category 5e standard of 100Mbit ethernet cables requires less than 1 error in 10 billion bits of information transmitted. So in terms of 24bit/96kHz that means 1 bit error every 3.5 minutes...

The ethernet protocol has bidirectional communication and error correction which will detect these occasional errors and fix them -- anything else would be unthinkable (imagine transmission errors which would corrupt your screen when you load up your emails or your internet bank). USB also supports this -- however the streaming mode (isochronous) commonly used with USB DACs is unidirectional and doesn't do error correction. This keeps the receiver simple. Nevertheless... with the numbers above in mind, it stands against any logical reasoning that one USB cable against another can create any measurable let alone audible difference in the sound produced by the DAC. I am almost tempted to launch a £10,000 challenge on this. ;-)

Couple of references:

http://en.wikipedia.org/wiki/Category_5_cable

http://en.wikipedia.org/wiki/Universal_Serial_Bus

http://www.belden.com/pdfs/Techpprs/ZeroBErrorRate.pdf
 
A

Anonymous

Guest
idc:
One area of cable manufacturing that is generally agreed upon is that the length of the cable is important. The longer the cable the greater the problems with signal transfer. For example USB cables reach their tolerances at about 5 meters.

So the argument is that below 5 meters there should be no problem. That works if you imagine a graph of sound over cable length which curves up, so initially it stays low and flat and then it curves up over 5 meters as transmission problems kick in. But imagine a curve which is rising from the very start and is more linear. After 5 meters the problems are obvious to all, but before 5 meters there is still the start of signal transmission degredation. It is not great, but it is still there.

That is my theory as to why digital cables can sound different and why some do not notice it and others do.

(I am not a scientist and please see the disclaimer in my bio!)

By the way, the 5 metres max length on USB cables is not based on transmission problems. The primary reason for this limit is the speed or light and the maximum allowed round-trip delay of about 1,500 ns. From wikipedia:

"If USB host commands are unanswered by the USB device within the allowed time, the host considers the command lost. The USB 2.0 specification requires cable delay to be less than 5.2 ns per meter (192,000 km/s, which is close to the maximum achievable speed for standard copper cable). This allows for a 5 meter cable."

I'm not sure why I suddenly felt like going on a rampage to dispel these myths. ;-) I guess I'm trying to generate some resistance against all the smoke and mirrors and spin and disinformation from certain manufacturers and cable makers.

http://en.wikipedia.org/wiki/Universal_Serial_Bus
 

idc

Well-known member
storsvante:I'm not sure why I suddenly felt like going on a rampage to dispel these myths....

Dispel them by reasoned and scientific argument. The issue is that dispite the science suggesting the contrary, so many people report hearing differences. So often that just becomes 'a rampage' by both sides, as you say storsvante.

I want to search for a unified theory that satisfies 'scientist' and 'audiophile'. So far that search has been plagued by mischief makers and evil doers.

P.S - I've been at the sauce again!
 
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Anonymous

Guest
idc:
I want to search for a unified theory that satisfies 'scientist' and 'audiophile'. So far that search has been plagued by mischief makers and evil doers.

Do you not think the unifying theory is the acoustic placebo effect...?

idc:

P.S - I've been at the sauce again!

No better time to discuss these things!
 

idc

Well-known member
storsvante:Do you not think the unifying theory is the acoustic placebo effect...?

No, for three reasons. One is that some differences are clear and the easiest way to hear/see that is to compare a £1 phono interconnect or Scart out of a £1 shop with anything that is at least made to a decent standard and you really should hear/see a difference.

The other is the wife. She rarely listens to music, but she can pick out different bit rates better than I can and she hears/sees differences in cables.

Thirdly, everything in hifi is made up of various components that work better someways than others and are built to differing standards. Otherwise we would all be buying a Tesco midi system for £50 and there would be no audiophile industry. It is streatching credibility to say that all audiophile products are just placebos, especially since so many report sound differences between even remarkably similar products.
 
A

Anonymous

Guest
nodnarb4444:is it just me thats read this thread and did not get any ov it

Hehe.

A patient given a sugar pill experiences a reduction in pain because they were told the sugar pill was a pain reliever. This is a known phenomenon called the placebo effect.

An audiophile given an expensive USB cable experience better sound because it was expensive cable and they were told it would improve the sound.

It's a little controversial to some, but I believe this is the reason people hear differences between USB cables. No need need to say "think" they hear -- because their *experience* will be that they actually *do* hear a difference... just like the placebo effect in medicine. And that's ok.
 
A

Anonymous

Guest
idc:
storsvante:Do you not think the unifying theory is the acoustic placebo effect...?

No, for three reasons. One is that some differences are clear and the easiest way to hear/see that is to compare a £1 phono interconnect or Scart out of a £1 shop with anything that is at least made to a decent standard and you really should hear/see a difference.

The other is the wife. She rarely listens to music, but she can pick out different bit rates better than I can and she hears/sees differences in cables.

Thirdly, everything in hifi is made up of various components that work better someways than others and are built to differing standards. Otherwise we would all be buying a Tesco midi system for £50 and there would be no audiophile industry. It is streatching credibility to say that all audiophile products are just placebos, especially since so many report sound differences between even remarkably similar products.

Ah, but there are several different factors at play here.

1) I'm talking about USB cables specifically and digital cables generally. Not disputing that analogue interconnects and speaker cables influence the sound. For analogue transmission, a small phase shift, distortion or whatever will directly impact on the result. Digital transmission on the other hand can be much more tolerant and doesn't really compare. It's like comparing sending a message in morse code, received and reconstructed by the other end, vs an analogue recording of the message itself. Clearly the 2nd case requires much more from the cable whereas in the 1st example the cable only needs to be good enough for the receiver to be able to be able to tell the difference between beep and no beep.

2) Your wife... How about you do a blind test on her to really test this? Swap around your digital cables a couple of times, without her knowing which one she is listening to, and see if she can consistently tell them apart!

3) 100% agreed, clearly everything is not placebo. I'm just saying it exists, and may play a greater part in some product categories than others.
 

idc

Well-known member
I don't get this placebo argument. If a sugar pill reduces pain then it becomes a painkiller. If it is a placebo it will only work in some occasions. The whole point of putting placebos into trials is to make sure the actual product is not just a placebo and it in fact actually works. So if a one say cheap cable works as well as another expensive one, then it is not a placebo, it is a good quality cable that has not been marketed as well as the expensive one. Many on this forum have worked that one out.

Furthermore, not enough discussion has taken place on different cable types and how they can/can't differ. I personally think that USB and digital cables do differ as much as analogue cables.
 
A

Anonymous

Guest
idc:
Furthermore, not enough discussion has taken place on different cable types and how they can/can't differ. I personally think that USB and digital cables do differ as much as analogue cables.

I tried to give this some real context a couple of posts back... I think we disagree. ;-) Would be interested to hear if you can back up this theory of yours in any way. How about blind testing with your wife? Share the results!
 

Gort1951

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Nevertheless... with the numbers above in mind, it stands against any
logical reasoning that one USB cable against another can create any
measurable let alone audible difference in the sound produced by the
DAC. I am almost tempted to launch a £10,000 challenge on this. ;-)


SNOREvante. You haven't seen my £50 USB cable, pre-launch you air strike at will.
 
A

Anonymous

Guest
storsvante, clearly you are right in your comments about USB cables, or any cables that carry digital signals for that matter. Yes, there are length limitations which will cause packets to be dropped, but you'll hear that mostly as blips or distortion in the sound, and anyway I'd strongly doubt that cables used for HiFi come near those limits.

There is no difference possible from one cable carrying a digital signal for another. What you are seeing here is a concerted push to put digital into the realm of fantasy HiFi land partly out of fear and partly for marketing purposes. This will no doubt soon be extended to hard disks used for storage, cables within a computer, motherboards, internal memory etc etc. It's all bosh and can be safely ignored.

idc, there are literally hundreds of texts and papers on this, not to mention an equal amount on the standards which apply. The theory is also covered in most computer diplomas and degrees, so you can take it as proven.
 

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