Originally Posted by Ratman
Digital audio, composite video and component cables should be RG59 or RG6, which makes them 75 ohm by spec.
Although 'regular' analog audio cables are not required to be impedance matched, it is usually recommended to use good RG59/R6G type cable for subwoofers to help with minimizing potential effects from RFI/EMI.
In other words.... if you have a "yellow" composite video cable laying around, it would be in your best interests to use that as opposed to any "skinny" red/white audio cable.
I've suggeted that line level signals in the audio range do not require RG59/6 and that other coax cable will be good enough. Everyone has these cables around. Why not let them try it, rather than speaking of their "best interests". They may not work but little time or money is lost.
Could you explain why RG59/6 is better at RFI/EMI rejection than coax of any other kind or impedance?
Bluejeans has an article
attempting to demonstrate the need for and superiority of double braided coax for analog audio. Although they note that it may not be best if there is an RFI problem. The BJ article is long on words and short on measurements of any import to their argument.
They article also says that a twisted pair will not work in an unbalanced line
. Put it to the test (I have). Make a twisted pair terminated with RCA pin plugs. An easy way to do that is to have someone hold one end of a pair of wires, pull them straight, insert them into a drill chuck and slowly twist them. Use it for a subwoofer or other line level analog audio connection. Dress it away from power lines, dimmer switches, and similar significant noise generators. Does it work?
Some argue in this forum and elsewhere, that today's A/V hardware is somehow more susceptible to hum and other noise than that of olden times and thus needs "better" interconnects. A moment's reflection will show that to be untrue. Switching power supplies, RF up through the giga hertz range, dimmer switches, etc., combine to make for a much noisier environment, yet most of us don't hear any of it. Is it because we are using quad shielded RG6 or because our audio hardware is good enough when it comes to rejecting noise?
Is it possible that a subwoofer cable could be the entry point for RFI? Certainly. Might it be audible? Yes. If you hear the local AM station it might be the cable