In Reply to: Re: Shield the AC instead posted by Mark W. on December 19, 2006 at 21:30:14:
Well, a lot depends on how you have the coax wired.If you are using the center for the hot wire, and the outer braid for the ground wire of the speaker cable, then the coax is operating in a manner that was intended, with the braid carrying the signal current.
In fact, the so-called ground carries the signal just as much as the so-called hot. See:
About cable "ground":
http://www.AudioAsylum.com/audio/cables/messages/503.htmlIn this case, the braid is a part and parcel of the signal circuit, and since a coaxial cable has special properties with regard to the relationship of the center wire to the braid, the inductance is fairly low, and the EM field of the signal it carries is MOSTLY contained within the coaxial cable braid, with minor amounts of the magnetic field extending past the braid, and the electric field radiating out into space surrounding the coax braid.
BTW, if this is a mini coax, then the DCR could be fairly high, given that it is unlikely that the center wire is very big, and even if the braid is of a decent overall gauge, the round trip of the signal must go thru the center wire for half the trip.
So far, so good, your coax is probably going to be somewhat resistant to the intrusion of AC power line radiation.
However, once you ADD a copper pipe to a more conventional speaker cable, even a "star quad" style, the amount of EM field radiated is a LOT more than a coax, and the fields WILL end up encountering the copper pipe, which, if grounded, will literally SHORT OUT those fields, and generate a counter current within the pipe, severely distorting the original signal in the speaker wires. Yes, a "star quad" geometry does have somewhat better EM field retention than a simple zip cord (also refered to as a figure eight geometry), but it is NOT in the same league as a coax.
Finally, if you are not using the coax in the above manner, then it is likely that you are suffering various forms of signal distortion, loss of HF content due to excessive inductance, etc. If the coax is steel cored, or has tinning or other coatings, then there will also be losses of signal quality, of a more subtle nature.
Jon Risch
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Follow Ups
- Re: Shield the AC instead - Jon Risch 18:07:50 12/20/06 (2)
- Re: Shield the AC instead - Mark W. 20:23:16 12/20/06 (1)
- Re: Shield the AC instead - Sean 22:28:58 12/23/06 (0)