My guess

On our comments page concerning break in there's much discussion about why long term break-in matters. The biggest question revolves around the nature of music itself: an AC signal, and why that should have any type of lasting affect to a cable or piece of kit. i.e. break in should not really matter, all things being equal. Yet, the evidence suggests otherwise. We know that when you send a musical signal down a wire, into a device, through a connector, that signal's energy orients the very molecules of the insulating material surrounding the conductor. That much is pretty well known and is referred to as the dielectric constant. The central question then becomes: why should this matter in an AC signal? AC signals move back and forth between + and - so the orientation it causes in the dielectric moves with it; thus, no permanent orientation is possible. Or is it? ​Well, as I mentioned in my earlier post, I am certainly no expert. I probably know just enough to be dangerous. But with that being stated, let's give it a go. Feel free to jump in and help me and the other readers get better clarity if you're more informed than I. First, a little background: If a material contains polar molecules, as are found in most insulators, they will be in random orientations when no electric field is applied. An applied electric field will polarize the material by orienting the dipole movements of polar molecules. In other words, think of each molecule that makes up the material we use for an insulator as that of a magnet: with two poles, a + and a - pole. The orientation of these poles is random throughout the insulating material. Now, put a signal down the conductor and an electric field is generated that will suddenly orient these molecules to all face the same direction. This uniform orientation of the molecules decreases the effective electric field between the insulator and the conductor slowing down the speed at which the signal travels though the conductor. So a couple of observations here: when no signal is applied through an insulated conductor, the molecules of that conductor lay in random order with respect to their charge. When an electrical field is applied (any signal) the molecules reorient themselves to be polarized in accordance with the signal itself - so a positive going signal would cause those molecules to flip their orientation around such that their opposite poles would face each other, + to - etc. - when the AC signal reverses the opposite would happen. For any signal slower than 10¹¹ Hz (certainly anything we listen to) that orientation of the molecules in the insulator reverse their orientation in lock step with the musical signal. So far, all this makes sense. Hopefully I haven't lost you. Hang in there. Depending on the type of insulating material, the act of reorienting the molecules reduces the electric field of the AC signal, thus changing some of its characteristics (less of it gets to your speakers). Longer waveforms polarize the molecules for longer periods of time than do shorter wavelengths and music, as we know, is a combination of longer (bass notes) and shorter (treble notes) wavelengths, the longer being generally higher in amplitude (loudness) and magnitude than the shorter. Thus, lower frequencies (bass notes), would have more effect on slowing down (limiting the electric field) the higher frequencies (treble notes) causing a shift in the sound quality, that one might suspect reduces the amount of high frequency energy (less bright sounding). And here's where it gets interesting. Suppose a low bass note is going through our conductor, say a cello bowing its lower string. At the same time, a higher frequency instrument such as a violin is also playing. Because the cello notes are louder and slower than the violin's, the orientation of the molecules will be predominantly in the direction of the lower notes from the cello. Thus, thus violin's energy will attempt to have the insulator's molecules follow its lead, but will be overruled by the cello. Why would this matter? Because every time the violin tries to dominate the molecular orientation and fails, its generated electrical field will be asymmetrical, thus it will not be pure, and we hear something different than intended. The type of insulator would matter much. If the insulator were air and the conductor air as well, as in a broadcasted signal, the music would travel at the velocity of of light through air. Place that same signal in a coaxial cable (like an RCA interconnect) and it will move at less than the speed of light. A polyethylene insulator, which is not a very good one, slows the velocity of the musical signal down to about 65% of the velocity of light: rubber even slower, at 56%; polyethylene foam insulation, 80% (because we added air to the insulator). Why would we care if the signal slows down to a percentage of the speed of light? We wouldn't, except for one thing: it slows down differently for different frequencies within the musical spectrum because of this dielectric effect. As I mentioned earlier, longer wavelengths (bass notes) polarize (orient) the molecules in one direction and because bass notes are generally significantly louder than higher frequency notes, this tends to swamp out the higher frequency's effects. Lastly, if we pre-polarize the insulator with a constant charge, like that of a battery (as the folks at Audioquest and others do), the varying wavelengths of music would have less of an effect on what we hear, since the polarization of the molecules in the insulator would be swamped out by the constant DC voltage. The only question I have: how then does long term use of the cable have any lasting effect on the insulator? My guess is that the effects of polarization of the molecules within the conductor are permanent; that when you remove the musical signal, especially those signals with lots of low frequency energy (as found in music), the orientation of the molecules in the insulator remain fixed. Their direction irrelevant, their organized state, meaningful. Whew! If you made it this far, congrats. Get another cup of coffee.