Cablu interconect RCA XLO Reference R3
XLO and 6N (99.99997% pure) OCC copper
In audio grade high-end cables and interconnects the purity of the copper is important and consequently specified to contain a percentage of “pure” copper, with the balance impurities. These are generally iron, sulfur, arsenic and additional trace elements. Higher-purity copper is specified as 99.99997% pure and referred to as “six-nines” copper.
A second factor affecting copper’s quality for high end cables and interconnects is the actual grain structure of the copper. When copper is “drawn” to size, the process creates a grain structure that are, in effect, tiny discontinuities in the copper. These discontinuities set up tiny circuits at the grain boundaries as the signal crosses each grain. The highest-quality technique used for drawing copper is called Ohno Continuous Casting or OCC.
Pure Copper Ohno Continuous Casting” PC-OCC is manufactured by a process invented in the United States in the 1920’s. This was called “zone refining” and was used in metallurgical and physics laboratories to produce very small quantities of ultra-pure copper for experimentation. As originally practiced, “zone-refining” utilized a special crucible heated only at one point, into which ordinary copper was introduced for melting and purification. As the copper melted, the impurities in it flowed to, and stayed at the hottest point, and pure copper flowed out through a controlled off-side opening in a process of continuous casting. Because the hot purified copper was cooled only very slowly, it annealed to contain only very few extremely long crystals (as much as 700 feet). This is important because crystal junctures are where remaining impurities, including ferrous metals and sulfur, gather and interfere with signal flow: the fewer the crystal junctures, the better the copper’s performance as a conductor.
XLO and shielding
Shielding affects sound. Even shielding done the right way acts like an additional capacitor, and creates "dump artifacts" that will audibly change the sound of the system. For this reason, most XLO cables are constructed without shielding. To keep the sonic effect of shielding to an absolute minimum, XLO cables that are shielded*
are insulated with shielding spaced as far as possible from the signal conductors and grounded outside the signal path. Even so, to the critical listener, neutrality may be affected, if only very slightly. XLO recommends that, for systems of the highest resolution, shielding for line level interconnects should not be used unless severe EMI or RFI problems make shielded interconnects necessary. It's generally preferable to deal with, or accept, any shielding affects to annoying hum, noise and static problems that seriously degrade the sound.
Different shielding materials have their greatest efficiency at different frequency ranges. By using two entirely different shielding materials (copper and aluminum), XLO/HT cables offer a broader range of protection from electromagnetic (EMI) and Radio Frequency (RFI) noise and interference.
* XLO shielded cables: phono cables; HT cables