QUESTIONS AND ANSWERS
Consequently, I've long wanted to conduct a test of my own, trying out premium cables in my own system, with my own music, on my own schedule, in my own home. I've also wanted to ask cable vendors pointed questions about their products. This article presented just such an opportunity.
At the outset, I sent pitches to several cable vendors requesting interviews and review samples. AudioQuest and Wireworld Cable Technology both sent a full package of review products; and their Founder/CEOs each spent the better part of an hour on the phone with me, patiently answering my questions.
The most vocal critics of audiophile cables have had little exposure to the products, maintains AudioQuest CEO William Low. "We don't completely understand phenomena like directionality, but we have empirical evidence and we have solutions. There are people who have expertise in related fields, but not audio cables. Because there are no variables to explain these behaviours, they say these effects are imagined."
The situation is similar to the mainstream view of amplifiers a couple of decades ago, Low believes. "Some people used to think that all amplifiers with similar specs sound alike. Cable has done a significant amount to take that view away. Naysayers are attracted to the frontier of what's considered outrageous."
AudioQuest says the polyethylene air-tube insulation used on its Boxer subwoofer cable minimizes smearing and preserves dynamic contrast, while the carbon-based noise-dissipation system reduces noise contamination of the ground plane. The cable employs solid-core silver-plated copper conductors, which the company says enhances bass articulation.
He says skeptics fall into a common philosophical trap: the belief that a chain is only as strong as the weakest link. "It's the biggest lie in hi-fi. Between capturing an audio event and moving air with a loudspeaker, every step, every device adds distortion. Each link in the chain has its own problems."
Power cords are a perfect illustration of this principle. An inadequate power cord will add distortion to that already present at the AC outlet - which may not be that bad. "The Romax in the walls of your house is 10- or 12-gauge," Low says. "While the copper is fairly low quality, it's solid core and there's minimum resistance. A standard 12-gauge AC cord has 63 strands to make it flexible. This creates the problem of strand interaction, leading to various types of distortion on the surface of the strands. AudioQuest power cables are not flexible because they have solid conductors."
Low compares audio reproduction to a series of stacked glass panes, with each pane making the scene behind a little less clear and a little more coloured. The goal for every stage, including cables, should be to damage the signal as little as possible, or to use AudioQuest's analogy, to make sure each pane is as transparent as possible.
Wireworld's goal is to build cables that sound as good as no cable at all, says CEO David Salz. For subjective evaluations, the company compares the cable under test with a direct connection between two components. For instance, to test an analog interconnect, Wireworld compares the cable with a direct connection between the source and destination components.
"To find out if you can make a better cable, you have to test to find out what you lose with a generic cable," Salz states. "We need to test the cable as it's normally used, then eliminate it and find out if we get any benefit. If we do not, the concept of an upgrade cable for that application does not exist."
But all generic cables cause losses, Salz says. "When we compare a cable with no cable, we hear a loss of sound quality: masking, compression, changes in tone. These are problems that a properly designed high-fidelity cable can cure."
David Salz, Founder and CEO, Wireworld Cable Technology: "When we compare a cable with no cable, we hear a loss of sound quality: masking, compression, changes in tone. These are problems that a properly designed high-fidelity cable can cure."
These problems include electromagnetic phenomena like eddy currents, in which the electrical signal inside the cable interacts with the accompanying magnetic field, causing information loss and non-linearity. The electrical signal can also interact with the insulation, adding noise and causing signal loss.
According to AudioQuest, the insulation can slow down the magnetic field associated with the electrical signal. This delay, which varies depending on frequency and amplitude, leads to phase distortion. AudioQuest says the air-filled foamed polyethylene insulation on its more expensive products absorbs much less energy, minimizing this effect. Its top-end models feature a Dielectric Bias System, in which a 72V battery is connected to a conductor that runs down the centre of the cable and to shielding around the outer surface. This "forms" the dielectric, the company says, aligning the molecules in the insulation so that they do not store and release energy. That technology is employed on the speaker wires, USB cable and NRG-10 power cords AudioQuest sent me for review.
Salz says dielectric absorption is a measurable phenomenon; but a larger issue is "triboelectric noise." This is caused by the buildup and release of electrostatic charges in the insulation, which can be generated by the movement of electrons adjacent to the insulation and by mechanical vibration of the cable, causing friction between conductor and insulation. Wireworld says the "Composilex" insulation on its current Series 7 lineup minimizes this problem.
These issues can arise even in applications that one would think are impervious to noise and signal loss, such as short USB cables. But as Low points out, sending audio from the source to DAC is different from other USB applications, such as printing and video. "Audio is time-sensitive," he says. "You're carrying a signal that has to be kept as a single homogenous package.
"Transferring a digital file from one place to another happens in the analog domain," he continues. "Ideally, a digital transmission is a series of square waves, and a perfect square wave requires infinite frequency response." If the edges are rounded off excessively, or if the signal is otherwise degraded, the USB receiver may not read the data correctly. The DAC may request that the data be resent, or use error correction to try to fix the damage.
Adds Salz: "The USB format is relatively fragile when it comes to streaming music. Relatively small differences in the waveform can affect the detection of the signal. We know that because when we add in a cable to one of these connections, the sound quality drops significantly. We can fix those, and produce cables that sound relatively close to direct."
What about cable directionality, another controversial claim? Low and Salz both believe it results from the way the conductor material is drawn during manufacturing. "RF garbage that corrupts the signal travels almost exclusively on the surface of the conductor," Low elaborates. "The structure of the conductor is not symmetrical. There's more noise, or random energy, when the cable is in the wrong direction."