Copper's sound

Yesterday's post on wire gauge sparked a few questions that needed to be asked. The constant pulling of wire through tiny openings, 10, 12, perhaps 20 times to get the wire size you need must have some effect on the wire itself. And the question comes quickly. What impact does all this copper pulling have on the sound of wire, if any? Talk about opening a hornet's nest, let me start out by suggesting my evidence is strictly empirical–I have spent a great deal of time listening to different coppers–and can report to you they do make a difference. And, depending on the use, a big one. So, let's look to see what's happening. Copper is a soft metal with high conductivity properties, second only to silver. Internally, most copper is formed from crystals and commonly referred to as polycrystalline (many crystals). Each of the crystals are contained in many small regions called grains and between the grains are boundaries (called grain boundaries). The electricity must pass through these boundaries on its travels. There is another type of copper, called single crystal copper, which is made not from pulling copper through small openings, but by casting it into long strips of the exact diameter needed. As copper is pulled through these many small openings, the grains are continually deformed, with increasing numbers of boundaries between the grains. The more you mess with the copper, the worse it gets at a microscopic level. And how you pull this wire has much to do with its character as well. For example, there are different types of copper, each depending on the process used: long grain, short grain, pure, impure, oxygenated, oxygen free, etc. Each type has different electrical characteristics that we can measure. But the question at hand is this. Are these differing electrical properties audible? Here's what I can tell you from my limited experience. First, what holds true for power cables doesn't always apply to audio cables, though in general they are close. I have never heard a difference when comparing oxygen free vs. oxygenated copper. I have heard improvements in long grain coppers and in particular single crystal vs. polycrystalline. And, for the record, there's a definite difference between copper and silver. But, by far the biggest improvements in sound quality come from construction and gauge of wire. That's at least my experiences.