To make oxygen-free speaker wires, cathode copper is melted in a large furnace. An oxygen-free environment is created by topping the copper with granulated graphite and reducing the levels of hydrogen in the air. This prevents the formation of impurities in the copper, which can then be turned into wires and covered with a high-quality plastic sheathing. Plastic sheaths can be clear to attractively display the copper wires and allow consumers to easily identify positive and negative wires.
The most expensive of the three main grades of oxygen free copper, C10100, or oxygen-free electronic (OFE) copper, must be finished in an oxygen-free environment to be considered 99.99 percent pure. Industrial applications include use in superconductors or situations when oxygen in the copper might chemically react with other substances in the environment. C10200 and C11000, respectively called oxygen-free and electrolytic-tough-pitch copper wire, are used in wiring most electrical devices, with purity levels at or above 99.9 percent.
Audiophiles believe that the lower resistance in oxygen-free speaker wires (C10200) allow for more powerful bass tones. The difference might be as slight as 1 percent, due in part to equivalent conductivity specifications. Over time, the slightly more impure copper C11000 available has increased in quality to compete with C10200 sales.
Other music aficionados prefer oxygen-free speaker wire because they may resist corrosion for a longer period. Corroded wires of any quality will negatively affect sound quality.
Oxygen-free speaker wire sells through a variety of local hardware stores and through online retailers. Oxygen-free speaker wire generally costs more than its slightly more common counterpart, but the difference is often less than 10 cents a foot. Pricing can be inconsistent, and higher-priced speaker wires often sell in the same price range, between $0.35 and $0.50 cents a foot. Speaker cables with C11000 copper can sell for as little as $0.16 a foot.
The impression that extra-pure speaker wires deliver a superior sound developed when sales associates noticed that regardless of the general lack of difference in sound quality between two kinds of speaker wire, customers preferred to buy speakers constructed with a name-brand, top-shelf wire. Businesses began aggressively advertising speakers in terms of the quality of the wiring, which fed consumers' perception that expensive speaker wires must be superior speaker wires. Some companies responded to the new marketing trend by imitating the look of high-priced speaker wires without actually using improved materials or methods.