CABLE SURVEY

[Pim]

Just my 2c, anything that relates in analog realm is more sensitive to types of able used. Shielding plays a big part, So is gauge.
However, when in digital realm, things gets shady. Some says data transferred in cables are in fact still analog(cause you need max distance for Ethernet cat5 cables or coax to work within specs). Cross talk between multiple cables (4 for usb) does play a part too...
It goes downhill from there on


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Here is an analogy that might help to understand how digital is actually an analog signal and how it gets influenced (or not)
As some of you already know I work on a drilling rig. We use logging tools that are in the drill string and send up down hole data. It's my job to run those tools and extract the data. I will try to explain without getting too much into detail. We use mud to pump through the drill string and then around out of the hole to clean the hole out. The tool restricts the flow of that mud ever so slightly at a given rate. The result is a difference in pressure on surface of about 15-30 psi over a pressure of 1500-3500psi. That little pressure change is our 'digital' pulse. The surface equipment converts the pressure change into an electrical pulse and the computer works out through and algorithm what the tool is trying to say.

And this is how I believe it relates to cable; The pulses are not all the same strength and they don't all come in at the right time either.
For the difference in strength it is quite simple to ensure you get it right; the computer sets a threshold pulse height and everything above it is a 1 and everything below is a 0. Simple enough and in digital cables it works the same way. So if there is a difference in Voltage height because the cable isn't perfect there still is no difference in calculation of 1's and 0's on the other end.

As for the timing it gets more complicated; That's where the algorithm needs to be smart enough to work out which 1's and 0's are in the right place and which ones are not. In my job that's easy; there are only so many values available so all the computer needs to do is work out what value is closest to what it 'sees'. It takes a pick out of a bunch, literally.
I could have 0.9993 and the next one up is 0.9998. There are no 0.999(4)(5)(6)or(7)s in the algorithm.

And that's where with music it gets more complicated. Music is 'organic' (for a better word) and there are no known values to pick from. Al the DA converter can do is 'see' 1's and 0's at a certain time and convert them into a Voltage change. If the timing is wrong coming in then the timing of that Voltage change is out. And therefore the timing of your music is out.

Timing of pulses can be influenced by (reflection of) magnetic fields generated by the current going through the cable and generating a current in other parts of the cable.
The same way a transformer builds a magnetic field in one coil by running a current through it and then it converts that magnetic field into a current in the other coil.
That's why in Cat 5 cable they twist the paired wires; the magnetic fields are countering each other out by being set up in opposed directions resulting in less of a chance to create a magnetic field from one wire large enough to create a current in the other wire (called Cross Talk and in Cat 5 cables it is where the twist gets un twisted at the connection where that Cross Talk is the biggest worry. This is called Near End Cross Talk. The less un-twisting, the better the connection)

Magnetic interference can also come from outside; Never have a power cable lie alongside a signal cable!

Conclusion; a bad cable will have a negative influence on music because the timing can be out. The question remaining (I'm sorry but this is where you'll be disappointed because I don't have the answer) is how bad does a cable need to be before the timing goes out or how good does a cable need to be to get the timing 100%?

As I said, I don't have the answer to that. I guess that will be in the listening

Maybe someone in the chat room knows a bit more about how data transfer gets 'checked' between sender and receiver. I would be very interested in that.

Cheers,

Pim