THE FIRST LESSON IN AUDIO CABLE DESIGN
The primary problem of audio cables was discovered and addressed over 100 years ago, when telephone companies struggled with problems of intelligibility over very long phone lines. British physicist/engineer Oliver Heaviside theorized that this problem was caused by inductive (electromagnetic) loss, and in 1893 he proposed the solution of increasing the inductive coupling between the two conductors to reduce the inductive loss of the telephone circuit. This solution was implemented in 1900 with telephone loading coils, which are still in use today. These coils are connected at intervals along phone lines to preserve the fidelity and strength of the signal.
The most audible differences among interconnect and speaker cables are also the result of inductive loss. While some listeners may actually like certain sonic colorations caused by cable inductance, these effects are always accompanied by dynamic compression and masking of the finer sonic details. For example, speaker cables with widely separated positive and negative conductors exhibit so much inductive loss that they distinctly thin out and compress the sound. WireWorld’s DNA™ cables have optimally engineered, closely-spaced conductors, which provide dramatic improvements in the preservation of harmonic structure, three-dimensionality and dynamics.
EVALUATING CABLES OBJECTIVELY
The superior fidelity of WireWorld audio cables can be demonstrated in objective listening tests, which show that they sound more like a direct connection than other cables. They also preserve square wave test signals better than other cables. However, laboratory testing and specifications can be easily misused in cable marketing and are often misleading. Test instruments are useful tools for product development and quality control, but the most important cable parameter of all is value, which can only be measured with human perception.
Some people still doubt that there are any real benefits to upgrade cables. A few double-blind ABX cable tests, which failed to prove that any cable differences were audible, would appear to support that position. However, ABX style listening tests were proven to be ineffective in the development of the compressed audio formats, such as MP3, and are therefore of questionable validity in cable testing. The listening tests performed by the Motion Picture Experts Group (MPEG) and WireWorld are ‘ABC-hidden reference’ tests, which utilize a ‘control’ such as a bypass (i.e., a direct connection). WireWorld has promoted double-blind cable tests for over a decade, because they provide valuable answers when they are done correctly.
In the fifteen years since we developed and patented The Interconnect Comparator™, our ongoing double-blind cable bypass tests have revealed that the most consistently audible cable effects are the tonal and spatial colorations caused by electromagnetic (inductive) interaction. Material upgrades can provide worthwhile improvements in fidelity, but sonic neutrality and transparency can only be achieved by thoroughly optimizing the inductive properties of a cable until it preserves the natural harmonic structure of a direct connection.
The materials used to insulate the conductors in audio and video cables can be a significant factor in their ultimate performance. Fortunately, some inexpensive materials, such as polyethylene and polypropylene, introduce minimal signal loss in cables. Many audio cables and some video cables are insulated with lesser materials, such as PVC, a lossy insulator that can degrade audio and video fidelity. All WireWorld cables are insulated with superior materials, including some specialized composites (Composite Dielectric Technology™) with unique benefits, which enable them to preserve as much of the signal as possible for their price.
DIRECTIONALITY & SHIELDING
The microstructure of copper and silver conductors is actually made up of individual grains of the metal. Unavoidable angular patterns in this grain structure can cause cables to perform differently in both directions. WireWorld cables are manufactured utilizing a proprietary Grain Optimization™ process that specifically controls the grain structure of the metal to produce the highest fidelity when the signal flows in the direction of the arrows printed on the cable. Some other brands of audio interconnects are directional because their shields are only connected at one end of the cable. The shields in WireWorld cables are connected at both ends to provide superior isolation from noise.
Of the various impurities commonly found in copper, oxygen is especially problematic because copper oxide can restrict conduction between the individual grains of copper. Oxygen-Free Copper (OFC) contains less oxygen than the common ETP (Electrolytic Tough Pitch) copper, making it a better conductor for audio and video cables. OFC is also known as 4-nines (4N) purity because it is specified as 99.99% oxygen-free. OCC is the trademark for Ohno Continuous Casting, the most advanced process for refining and casting copper and silver conductors. OCC copper and silver conductors are guaranteed to be 99.99997% (6N) pure. Superior conductors can improve the Performance of audio and video cables, but they cannot correct cable design problems. For example, silver is 6% more conductive than copper, and silver oxide is a much better conductor than copper oxide. These advantages improve resolution, which tends to magnify the colorations caused by the design flaws of most silver audio cables. WireWorld’s silver cables are carefully engineered to maximize the advantages of silver conductors for even cleaner and more lifelike sound and imaging than the same designs with copper conductors.