When should stranded wire be used for audio cables in a PA system? What is the “electrical skin effect”?
Q:Tim <2207leung@hknet.com> wrote: When should solid core or stranded audio cables be used in the public addressing system that broadcasts an audio with sound bandwidth 7kHz? Any reasons for the choice? A: Art Ludwig – aludwig@silcom.com – provided the following answer and analysis: For higher audio frequencies, the “skin effect” in practical conductors forces the current to be close to the surface. This increases the effective resistance of that wire. The “Skin depth” – for planar geometry and wire diameters much larger than this depth – is where the ac current diminishes to 1/e of the surface value. Round wire conductors should be less than three times that planar skin depth in diameter for there to be a “small” effect. One way to circumvent the problem is to use stranded wire, each stand insulated from the other and woven in a special pattern that varies the radius and thus the magnetic linkage. This is called “Litz wire”. Audio designers may bundle several smaller gauge insulated w
