Why do digital cables sound different?

Gentlemen,

There are always Impedance mismatches.. the trick is
to minimize... usually we have tolerances at 10%...Even
for high speed stuff. Impedance mismatches do cause RF current problems BUT if terminated it will be minimized.

Forgive me for coming late into conversation...

From what ive seen there is a major flaw in the spec itself The #1 contributer of EMI is the rise time. The quicker it
is the more EMI emitted. A common misconception is the Freq
is the culprit not true. Its seems to me that the rise times
are faster than needed for application. If some one knows why they used the 3mhz with a 12-15ns rise time... Please let me know? It doesnt make sense to me. Although those numbers are prehistoric it is asking for excessive EMI with
faster rise times than needed. Typically you would see a rise time more like 30 maybe as high as 80 for that type
of frequency.

Its like saying take 15min to drive to the store (a 5 minute drive) and then RUN in side and try and make up for lost time when you get there.

As far as termination I agree with Audioeng. You have have
termination in place at reciever end. Its the reflection back thats the killer... Backwards crosstalk is evil sh*t in any system.

Sean,

I can tell you there is an 80-90% chance that the
last reply you sent went thru a OC192 backbone router that is running at 10ghz and the 10% mismatch rule applied to that product too and it works real good. We have to allow for material caused mismatches.. PCB fabrication is a major
contributor as is cable construction.

Sorry if im overstating the odvious BUT Its a fact of life...mismatches will always be there just like taxes.

Sean,

I need to talk to your tax guy :-)

I agree with you 100% its all about the benjamins$$$
I never said i like mismatches... Why do you think i
spent big bucks on my cables... But there are still
other problems on the chain and unless you youself
are designing AND fabricating the product including
the transistors you are at the mercy of ACCEPTABLE
tolerances. Welcome to the real world.. I dont like
it either BUT its reality.

Maybe you can explain to me how to get better impedance
control than what the fab houses can fabricate the product
for? In other words we design these "low tech" 48 layer
10 thousand connection PCB's running at 10ghz and 50 ohms dead nuts on... Its like having 10 thousand interconnects in a 5 sq foot area... What are we gonna do have kimber cable wire us up something?
We are forced to rely on material and fabrication tolerances. There are only two board houses IN THE WORLD that can fab that PCB for that"low tech" backbone router.

How would you do it?

Sean,

Can i still have your tax guys number? just kidding.
I agree...audio and high speed are two different worlds
and I do get them confused sometimes...

Forever,

I think you brought up some very good points. The more
i think about it the more im thinking perfect length
of wires might not be ideal for audio. Hmmm.. So what do
you say guys lets sell different lenght MATCHED cables
and get rich?

Best regards