Arrows on cables --- which way to connect?? (1 Viewer)

[Saurav]

OK, I think I see what you're saying. When you said "the above analysis" you meant your DC statement, not my LED statement. That finally makes some sense
Anyway... the rest of the questions in my previous post still stand, I think.

 

[Tor Arne]

Jeremy!
I WAS reading! I didn't say anything about the shielding, I just commented on the directional conductor subject.
Actually, grounding in only one end scares me a little. This means that the signal may actually have extreme voltages when reaching the receiving end, because of differences in ground voltage between each component. They don't share a common ground like this.
Just a thought.
TAH
Norway
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[brucek]

Saurav,
The answer to your LED question is no. An LED is normally only used in "DC" conditions so its light can be seen when biased in a forward direction. With "AC" applied they act as a normal diode and will rectify the signal without visibly apparent light as the electroluminescent light emission in silicon doesn't respond fast enough. But in either case a completed circuit loop is required for any current to flow.
I don't seem to be able to make my point that the shield of a coaxial cable is at ground potential and is designed to protect the core "business" wire from extraneous signals. It does everything you would ever need done with respect to RFI protection.
If I add a second wire to complete the ground connection of an interconnect the shield is hanging in the air, but still connected to ground. Electrons will not travel on this wire since they already have the second core wire to travel on, so there can be no directional properties.
If I use your postultion that some unidentified current travels down this open ended wire to the RCA shield it is connected to, then it will see the "second" ground core wire and have a clear path to the other end of the interconnect where it is connected. Again, there can be no direction properties or difference, perceived or otherwise with directional cables.
Cable companies love this stuff, because people eat it up and actually believe it.
Tor, reread this thread and you will see that both ends of the cable are indeed grounded. If they weren't you would have any audio passing through the cable.
brucek

 

[Saurav]

I don't seem to be able to make my point that the shield of a coaxial cable is at ground potential and is designed to protect the core "business" wire from extraneous signals. It does everything you would ever need done with respect to RFI protection.

No, you have made that point adequately. I can see how you're saying that it's not necessary, I just felt that that was a different argument altogether, that's all.
Anyway... end of story

 

[Ken Bohn]

Good discussion guys, thanks BruceK.
I really pulled a no-brainer when checking the outer conductor yesterday. I have been working with so much shielded twisted pair wiring and medium voltage cable installation design and automatically applied the same theory to RCA's without thinking about it. I had never actually thought about the direction arrows before since I always just jumped to the my theory that it was to do with shielding. This thread was the first time I had reason to question my reasoning and it has led to an important re-eductation. Geez, I spend all my time solving client electrical problems at work and then I put in zero thought as to how some of these things effect my hobby.
I am now convinced that the directional arrow is a joke, it will take a solid electrical theory to show me otherwise. And even then I would be very skeptical as to the impact on the sound unless it was a very good theory. Looks like I am going to be quizing a cable rep for some info the next time I run into one.
Ken