Solid core conductors in Romex (power cable in our walls) have less surface area than a same-gauge bundle of stranded wire, commonly found in stock power cables. Thus it can be said that solid core wire has less Skin Effect than its counterpart of many fine stranded wire. Skin effect describes the ability of conductors to pass high frequencies: more skin effect allows more high frequencies to pass.
It has been speculated that finely stranded power cables sound brighter and improve high frequency performance in amplifiers due to greater skin effect. I agree with this notion but not for the reasons commonly given. It is thought greater skin effect permits faster current transitions when feeding diodes in the power supply. And while this is a nice theory it has several big holes in it: there are no higher frequencies than 60Hz in a pure AC signal, and even if there were, the loss of bass and weight in the music - a quality associated with stranded wire in power cables - is not explained by a wire's ability to pass high frequencies. This is because passing high frequencies is never at the expense of passing low frequencies in a conductor of adequate gauge.
Instead, let me offer a different viewpoint. After years of careful listening I have concluded music does not actually lose bass, weight and heft with stranded wire. What I believe happens is the upper regions of music become exaggerated, the lower registers remain unchanged. This tilt towards brightness makes us believe we lack bass, when in fact we gain highs. It is the balance that is unnatural.
And the $64,000 question is, why do we gain brightness from increased surface area of wire? Noise. We do not live in a clean world. Our power lines are antennas and carry loads of high frequency energy. Greater skin effect allows more of these high frequency noises to pass into the equipment, and the opposite is true with solid core. Thus, the wire acts as a filter. It's relatively easy to prove and tomorrow I'll suggest how.
Stay tuned. Tomorrow's post will be the last in the power cable series and we will move on to power amplifiers, which have been on my mind as of late.