In theory a high-end cable should last forever. With a few exceptions, cables don't possess active parts that can wear out. Also, since high-end cables are made with far more care, it stands to reason that fewer would fail after time in the field due to cold-solder joints and other manufacturing defects. But does a cable that's say, fifteen years old, (yes, I have quite a few that age) display any audible signs of deterioration in performance over its "lifetime?
And what is a cable's lifetime, anyway?
To find out the answers to these burning questions I went to the sources - the heads of four cable manufacturers; Bill Low from AudioQuest, Ray Kimber from Kimber Cable, Karen Sumner from Transparent Cable and David Salz from WireWorld.
Ray Kimber said, "I posed that exact question at Audio Asylum years ago, in the middle of a debate about cable break-on, a good discussion followed. My thoughts are that a cable could deteriorate. The jacket could degrade depending on the plastic used and the environment (UV exposure for example), and the conductor could oxidize (such as if moisture was captured under the jacket during extrusion). So, there are lots of factors in that question.
Cable manufacturing has come a long way since its early days. One major cable manufacturer used a water-permeable PVC jacket in one early version of their cables, and after a couple of months the metal inside began to turn green from exposure to high levels of humidity. Nowadays the best manufacturing facilities are well aware of the hazards of humidity in the production process."
A Cable's useful life depends on many factors, not the least of which is environmental. In a dry environment where they aren't exposed to physical abuse a cable can last a very long time.
Ray Kimber told me, "We have customers with cable from 1985 that's been sent in for repair - usually it's pets. Kimber has sold 1000's of miles of PBJ cable, which is a Teflon product, so unless mechanical trauma is involved it could last hundreds of years!"
David Salz's take on the issue of cable aging was concise and to the point, "My position is that cables only have an expiration date if their design does not adequately protect them from internal corrosion and breakdown due to bending stress. High quality cables actually tend to improve with age as they continue to break in as they are used."
Karen Sumner wrote, "Well-made cables oxidize relatively little over time. Find out if your old cables are well made. Do they have impermeable, pressure-extruded jackets and shiny, hard solder connections with high silver content solder that seal the termination points? Do high-grade connectors cover the connections to help prevent oxidation?
Severe oxidation actually damages the crystalline structure of the conductors, and there were some designs that employed termination techniques that changed the integrity of the conductors from the start. It's a condition that only worsens over time. I've seen old cables with Litz conductors where the strands have turned black and flake and crumble apart as far as a foot up the cable!
If someone has old cables with lacquer-coated conductors in them, replace them if there is any visible oxidation. Audio equipment archivists should be aware that quite a few audiophile cable brands from a decade or so ago used some sort of Litz-conductor construction. If your old cables do not have any lacquer-coated conductors and they are well made, then enjoy them totally until you are ready to upgrade them for newer technology and more performance."
Bill Lowe summed up, "As for degradation over time, there is one main area of vulnerability - cables with multiple bare-copper strands touching. While silver-oxides and tin-oxides are conductive, copper oxides are semi-conductors. This means that the conductivity of the connection between strands varies with signal amplitude. It's a dynamic distortion mechanism. Depending on the particular insulation used, this can be an essentially theoretical vulnerability, or one guaranteed to cause degradation over time.
There are always the freak things that might go wrong on rare occasions, however corrosion of bare-copper strands and the resulting increased distortion at the strand interface is to me the only predictable source of long term degradation in cables."