Skin deep

What is it we actually know about electricity and wires that might help us figure out what's causing us to hear differences in cables? In yesterday's post I told a story of my first encounter with power cable differences. I found that wire with many thin strands sounded significantly worse than the same thickness wire with only one strand, better known as solid core - though this is a misnomer since most wire is solid in its core. What is the difference between many fine strands of wire and a single thick one? Increased surface area, known as skin. Electricity travels mostly in the outer skin of a conductor, less so in the middle 'meat' of the wire. This interesting bit of detail is known to engineers as the Skin Effect. The math is complicated, far beyond my meager skills, but I can offer an overview. Electrons travel more freely and without much resistance closer to the surface of wire because their travel is less impeded by magnetic effects deep inside the wire. This effect is more apparent as the frequency of power increases, thus, higher frequencies travel better on the surface than in the wire's core. The improved high frequency performance of surface area can be taken advantage of by reducing the core thickness of the wire and using many smaller, thin strands to regain the desired thickness. Like angel hair pasta vs. linguini, many fine strands have more surface area, relative to their cores. Some designers have even gone so far as to make hollow core wires, like we do in our power cables, to get even more surface area at the expense of the inner meat. You might ask at this juncture why stock power cable manufacturers cared about increased skin effect and improved high frequency travel, when the power sent down the cable is slow moving, at 50Hz or 60Hz? The answer is simple. They do not care and never have. Stranded cables are used to build power cords because they are more flexible than thick solid core. It's that simple. If you've ever tried to muscle around one of the many Audiophile power cables made from solid core wire, you'll appreciate my words. And in-wall wire is solid core because it is easier to terminate and flexibility is not a benefit. But why would better high frequency performance in power cables matter? We'll offer some opinions tomorrow.