"but no mention of a tight characteristic impedance tolerance so this could vary wildly along the length of any cable "
Oh! get real! You are just being silly! I guess you have neve rhad anything to do with real engineering or manufacturing
Oh! get real! You are just being silly! I guess you have neve rhad anything to do with real engineering or manufacturing
No, but a little research on your part on how SPC works might be educational. I gave the name of one major equipment producer, there's many more. This stuff is produced at high speed with superb Cpk.
You do understand what the term nominal in the spec means?
Without a spec regarding tolerance we have no idea what is the variation about the nominal 75ohm.
Belden themselves even state this http://www.belden.com/docs/upload/Precision-Video-Cables-Part-1.pdf
Actually, we do know the variation. Any process in control will have a Cpk over 2, and most coax manufacturing has Cpk over 3. Again, so what? It affects nothing.
Calculate worst case SWR.
Calculate worst case SWR.
This is hard for me - how can a cable be 'directional' if changing it around doesn't make an audible difference?
For example, turning it around probably makes it look different - is that enough to call it 'directional'?
Jan
Simple - It may have different performance characteristics between each direction explained by variations in impedance along the cable which are not symmetrical about it's mid-point. I didn't say it wasn't audible - I made no claim in this regard.
I think we are into trolling territory here ...
No cable manufacturer is producing cable just for SPDIF! That is just an insignificant part of the market. And very low speed. And not worth the bother.
The only way that comes to mind for me is one of construction . I.E. using a balanced cable in an unbalanced way rca with shield only connected on one end and the - line connected at both end to the rca outer , + connected to the center of the rca.
I see you have 20ish posts since you joined here a few months ago.
Why don't you sit back and read a bit around what it is like here before you post here. Because if you don't, you are well on the way to making yourself look like a complete and utter pillock.
That may need some translation for our friends across the pond, but I am quite sure you know exactly what I mean.
Come on, do us all a favo(u)r, I am sure you have something useful to contribute.
Thanks for your input, DEFjammer ... people may get hung up on what I happen to be experimenting with at the time, but this is purely in the context of "how loowww can you gooo?!" 😉 - IOW, what ultimately determines whether an audio system, no matter how cheap, is capable of generating acceptable sound or not - obviously with higher quality elements it's theoretically easier, but that doesn't necessarily translate to good sound, on the ground. I just recently visited the home of a fellow member, highly tweaked, quality, respected components - very competent in many areas, but it has issues holding back its potential, the same that I hear over and over again ... the clarity of low level detail is what suffers, and improving that is key to getting optimum sound.
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It can actually reduce cost in continuous processes. I've given you the key concept, now it's time to do some studying.
Just point down and let her know that that pair is staying there. Its like this, if she can beat you up, then how can you protect her? ......... Next man to test please, this one failed the Darwin. (-:
After 30+ years with my Designer wife, pretty much I need to say, "It will sound better.", and I get a chance. Of course, it has to look good to her, too....
It isn't an explanation because the theory is wrong, they are not directional...
The two main impedance matches in an SPDIF transmission are the connectors, but then most SPDIF interfaces tend to have a termination resistor of 75R, this negates any impedance mismatches, there is plenty of info on the web for terminating digital lines, Howard Johnson has a whole chapter on it (6 I believe in High Speed Digital Design), as does Eric Bogatin and many others.
And to re-iterate impedance mismatches are not a big concern for normal SPDIF interface, or for most digital running around that clock speed and higher (low double figure MHz), even when you pay the exorbitant costs to have a impedance controlled PCB made you will only get +-/5% at the top end. looking at some real designs (standard not impedance controlled designs), out there working in the world, trace impedances range from around 50 to 120 Ohms single ended, depending on the board, complexity and number of layers.
So this is not an example of cable directivity, especially where SPDIF signals are used.
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