Cables: Perception v. Reality.

Will the nonsense being perpetrated about the audible and measurable properties of audiophile loudspeaker cables never cease? How many competent electrical/electronic engineers and physicists must speak out on the subject before audiophiles "wise up" and cease spending absurd amounts of money for hi-tech-looking cables that actually provide no audible improvement over inexpensive, quality, #12 AWG zip cord?

Having participated during the past 30-plus years in a significant number of blind, double-blind, and non-blind listening sessions intended to discover and delineate audible differences between various audio components, including cables, I have concluded that non-blind sessions are worthless and a complete waste of time. But, most audiophiles continue to believe that they can and have heard audible differences between cables during listening comparisons. Indeed, most audiophiles (including the undersigned) have probably thought that they heard differences during non-blind listening comparisons because such comparisons are seldom properly controlled to eliminate biases traceable to:

1. The well-known "placebo effect," which a psychologist would describe as a perfectly human trait that leads people to hear what they believe they should hear when coached by a zealous salesperson or preconditioned by cleverly worded advertising jargon and claims. (Medical doctors regularly use placebo pills to treat imagined maladies that do not respond to conventional treatment).

2. Advertised performance claims that cannot be verified by accurate measurements made within a well-equipped electronics laboratory by competent engineering personnel.

3. Cleverly and seductively worded advertised claims for superior design properties that cannot be traced to the well-known and well-understood teachings of "transmission-line theory" (a university course required for most undergraduate students pursuing an E.E. major).

Let's briefly examine the placebo effect as it applies to listening comparisons. Several members of the audiophile cable industry firmly insist that they can clearly and consistently discern audible differences between their cables and those of other manufactures. However, when asked whether they can do so if the comparisons are made under "blind" conditions, i.e., not knowing which cable they are listening to while switching, they usually reply that "such conditions confuse and dull a listener's powers of perception, making normally audible differences imperceptible."

But, without a properly implemented comparison methodology, the placebo effect will almost always predispose even the most competent and well-intentioned listener to "perceive differences" -- when no actual differences exist. It seems to me that to believe otherwise is to ignore the need to apply logic and reason. To be meaningful, listening comparisons between cables must be conducted in a relaxed, non-intimidating manner, within a listening room possessing excellent acoustical properties, the latest and best state-of-the-art equipment, highly accurate pulse-coherent loudspeakers, etc. Every effort must be made to keep the listener stress-free and psychologically neutral. Within such a setting, our own "blind comparison sessions" begin with the following stages and procedures:

1. While listening to a variety of music and test tones, switching between two or more different cables takes place with the listener knowing which cable is being heard. The listener is asked to identify and comment upon what audible differences he or she believes that he or she might be discerning. These perceived differences are noted and transcribed.

2. Without interruption, the listener is led to believe that the cables continue to be switched when, in fact, switching no longer occurs and the same cable is actually heard during the entire listening period. (This segment of the "listening comparison" helps establish the listener's susceptibility to suggestion).

3. During the last segment of the cable comparison evaluation, the cables are randomly switched while the listener attempts to identify which cable is being heard and what audible differences he or she hears.

From numerous repeats of this kind of cable comparison evaluation, we have concluded that there simply are no audible differences between quality #12 AWG zip cord and expensive, hi-tech looking loudspeaker cables within a properly operating audiophile system. When actual audible differences were discerned, they could always be traced to equipment interface problems, e.g., ultrasonic oscillations or other forms of amplifier instability traceable to the low inductance and/or high capacitance of low-loss, high-performance loudspeaker cables -- which should have provided the best audible performance.

From a purely theoretical point of view, transmission line theory teaches that the characteristic impedance of a cable should be approximately equal to the average (or geometric mean) impedance of the load. As such, the teachings of transmission line theory can be used to design loudspeaker cables with properties that provide a nearly perfect match between the output of the circuit of most power amplifiers and the input impedance properties of most loudspeakers. It is a pity that the designers of most expensive, high-tech-appearing loudspeaker cables appear not to be aware of this opportunity -- since few, if any, of the most expensive speaker cables possess the required electrical properties. And, without exception, all of the potentially audible properties of loudspeaker cables can be accurately measured and assessed by competent engineers using readily available (though expensive) laboratory equipment. Such equipment includes a lab-quality digital RCL bridge, vector impedance meter, network analyzer, etc.

All competent designers and manufacturers of audiophile cables should possess such equipment and use it. If they did, they would be able to publish accurate values of inductance, capacitance, loss-resistance, VP factor, and frequency dispersiveness for their cables, along with a lucid explanation for interpreting them.

Funny, then, that most manufacturers of expensive audio cables choose not to provide any measured data or explain how to interpret it so that knowledgeable audiophiles might be able to compare cables according to meaningful electrical performance specifications, preferring instead to show "graphs" that depict properties such as efficiency, Joules, etc., that have no meaning or relevance whatsoever with respect to assessing the performance of loudspeaker cables.

The important, bottom-line question is really simple: does any reasonable justification exist for using expensive, hi-tech-appearing loudspeaker cables rather than a high-quality zip cord for lengths of loudspeaker cable shorter than about 30 feet within most high quality audiophile systems? Other than searching for the absolute highest degree of measured accuracy that is provided by cables designed in accordance with the transmission line theory described above, probably not.

However, a lot of the enjoyment that many of us derive from our unending pursuit of "perfect audio reproduction" has as much to do with "perceived improvements" as it does to actual improvements in system performance. Thus, for some people, perceived advances are every bit as important as real advances -- and are "perceived" to be worth the price.

-John Dunlavy CEO Dunlavy Audio Labs Guest Contributor