speaker cable
Reply #4 – 2012-11-07 14:46:47
Really all cables be they power, signal interconnects or speaker should be twisted! (save for co-ax) Jim Brown writes: Twisting Cable pairs are twisted together for two very important reasons. First, bringing them more tightly together reduces the coupling of external magnetic fields (while increasing the coupling between the conductors) by reducing the loop area between them. Second, twisting them together in a very symmetrical fashion causes any noise coupled onto one conductor to be more perfectly cancelled (in the receiver) by noise coupled onto the other conductor. Twisting reduces both magnetic (inductive) and electric (capacitive) coupling. To understand how twisting does this, consider a magnetic field from a source that is closer to one side of the cable than the other. At any point along the cable, one conductor will be closer to the source than the other, so the induced voltage will be greater in that conductor than in the other. But one half twist along the cable in each direction, the other conductor will be closer to the source, and so will have the greater induced voltage, but the polarity will be opposite. The more symmetrical the twisting, and the "tighter" the twisting, the more perfectly the two induced voltages will match each other over the length of the cable, and thus be better cancelled by the receiver. The number of twists per unit length is called the "lay" of the cable. Twisting also reduces capacitive coupling onto the cable, and for the same reasons. The ability of twisting to reduce coupling extends to very high frequencies. Ethernet networks run on high quality, unshielded, twisted pairs at frequencies in the hundreds of MHz, and require good crosstalk rejection to function well. Cables, Transmission Lines, and Shielding for Audio and Video Systems by Jim Brown - Audio Systems Group, Inc.http://audiosystemsgroup.com http://audiosystemsgroup.com/TransLines.pdf