Do Cables Wear Out?

OK, JWP, tell us how much the measured resistance of 8 feet of 12 AWG speaker wire changes over 7 years. You've made the claim, and you've told us you have a LOT of experience, so show us what you've got.

By the way, litz is not a coating but rather a type of wire configuration composed of a bundle of smaller wires, each coated or not.

http://www.litz-wire.com/

JWP, just because you are older than me (you have a lot of experience) doesn't mean that you understand oxidation nor corrosion in metals. Silver oxide or sulphide which someone thoughtfully pointed out might conduct better than copper, but not better than silver. Insulated wire is not exposed to the atmosphere and thus does not coorode there, but at the exposed ends. I too would like to know the increase in resistance in a piece of wire after 10 years.
Salut, Bob P.

BobP - I never said that the resistance of copper conductors changed over time - go back and re-read my comments. I said that the surface of the copper conductors OXIDIZED over time and that this created several sonic "losses" in the cable compared to when that cable was first made. As for Kenyonbm, thanks for the link, but in the AUDIO cable business, "Litz" wire has been generally accepted to mean coated or enamaled wire- sort of the same way Kleenex is generally accepted as being a tissue The link was kinda interesting tho in a global sort of way. Look - I responded to the initial question and explained what was going on and why because of my experience. If some of you want to get into endless nit-picking, like whether or not a cables jacket and heat shrink prevent oxidation (it doesn't, but it does slow it down ), be my guest - knock yourselves out, have fun, enjoy... I suppose this is why some very knowledgable people now no longer bother trying to help others in the hobby.

This person, who I quote without permission, has taken the time to educate him/her self and presents facts and analysis and recommendations logically and modestly.

http://hometheaterhifi.com/forum/showthread.php?t=1507
"Chu Gai Chu Gai is offline

Excuse me for interjecting here, but there's a substantial amount of misinformation and erroneous conclusions given in this thread.

First let's begin with some resistivities for the materials being discussed. Resistivity is the opposite of conductivity so the smaller the number, the less intrinsic resistance (greater conductivity) it possesses.

Copper: 1.7 X 10^-8 ohm-m
Silver: 1.6 X 10^-8 ohms-m
Gold: 2.4 X 10^-8 ohms-m
Silver Sulfide: 1.5 to 2.0 X 10^-3 ohm-m
Silver Oxide: 1 x 10^+9 ohms-m

As can be seen, silver has the lowest resistivity but gold and copper are not all that far behind. When talking things like speaker wire, the advantage of silver over gold is about 6% but that's an advantage that's more than offset by going one up on the gauge of copper.

Now, I've given the values also for the oxides and sulfides of silver. I don't have the values for copper readily at hand but I do seem to recall that copper oxides, and there are two forms - cupric oxide: CuO and cuprous oxide: Cu2O are in the vicinity of 3,000,000, that's 3 million times, worse than that of silver oxide.

One thing that should be obvious from the little table above, is that by no stretch of the imagination should one consider silver oxide to either be as good as a conductor as silver or in fact, desireable. As a conductor, it is 6,250,000,000,000,0000 or 6 quadrillion times WORSE. That makes it more like an insulator in my book or a semi-conductor if one wants to be generous. The reason why you get some conductance and might not even notice it even if its there, has to do with the thickness of the layer. If the oxide is perfectly uniform, it can be thin enough to not make a whit of difference. Further, if its thin enough, the simple act of inserting and removing an RCA, in other words, the friction, can be enough to dislodge enough material to expose enough silver. It doesn't take much to do the trick.

Along the lines of the silver oxide battery analogy, you're overlooking that a battery is a cell. One side, the positive, is indeed silver oxide but its not some disc of the material. Rather its in a sort of suspension and typically admixed with other chemicals such as manganese. The other side contains zinc. To bridge the two dissimilar substances is a suspension of sodium hydroxide. When one connects the anode and cathode, such as when one turns a light on, a circuit is completed and this allows the flow of electricity since the battery is now undergoing a chemical reaction which in the case of the silver oxide battery has a potential of 1.55 volts. Some may recall doing experiments such as taking a lemon and sticking in strips of copper on one side and zinc in the other to power a tiny motor.

Having a piece of silver or copper and exposing it to the air does not necessarily result in 100% oxidation. Perhaps a better term is that the base metal tarnishes. Tarnishing is what happens when this metal is exposed to the atmosphere in your particular environment. The atmosphere doesn't just contain oxygen though. It also contains particulates, moisture, carbon dioxide, sulfides, and a host of environmental pollutants some manmade, some generated from acres of forest fires, volcanic eruptions, and cows farting. Seriously.

Silver and copper all have a different affinity for these pollutants. In the case of copper, not only are oxides formed but carbonates (CO2 and water), sulfides, and hydroxides. Gone long enough, these are particularly hard substances and often to restore the copper, one must take strong, abrasive measures. Silver on the other hand, is not so prone carbonate formation but it does readily form sulfides, which you'll notice as a dark color. The silver oxide is essentially white or grayish.

Tarnishing, as in the case of RCA's, spades, or bananas, is a phenomenon that should be discouraged as unless you've got a perfect, tight, metal to metal contact that excludes the atmosphere 100%, it'll always be going on. Fortunately there are approaches that render this a moot point. Plating over with gold is inexpensive but one should bear in mind that gold is a soft metal and that the plating is often not thick - 10 or 20 microinches, maybe less. Further, unless the metal that's being plated over is quite smooth, if you're the sort of person that's always swapping out connectors, it won't take long before you've literally worn away the gold. One can look at rhodium or chrome or shiny nickel platings which are more durable. The thing is though, they don't quite have the same panache for many people as gold.

I've found that its not such a terrible thing to pick up some contact cleaners and related products. Caig used to, maybe still does, have small tubes of assorted products that one can use as routine maintenance, say on your birthday, to clean all your connectors. If you don't like Caig, use somebody elses. This yearly routine, or twice yearly if you're so inclined, will generally provide you with peace of mind and the knowledge that your cable/instrument connection is not a cause for concern."

Again, a pretty good source of information is available with very little effort.

The point I am trying to make is not that I am smarter than everyone else, which I am not, but that it is very easy to find truly informed sources to verify things before you post miss-information.