Originally Posted by Nuthed
Originally Posted by will95
I have a pair of what looks like ~10 gauge copper speaker wire. These were purchased many many years ago and over time the copper side turned a dark green color. Does anyone have any experience with speaker wire turning "green" (oxidation or maybe this is a reaction between the copper and the sheathing material). Anyone have any info on what causes this? If this is oxidation, is there a way to prevent it from happening on new copper cable (some way to seal the ends to prevent oxygen/water vapor from getting into the cable)? Also, aside from the appearance issues, how would this affect the resistance/performance of the wire? I haven't tried to measure the resistance of the wire yet.
I'm the guy around here the "real" audiophiles like to make fun of and chide. However, battery cables and spark plugs wires go bad eventually as well.
Yes spark plugs wires do go bad due to corrosion and flexing, but their operational environment is pretty horrific compared to the sheltered lives of cables indoors.
You might be surprised to find out that spark plug wires generally have no copper in them.
Here's a reference that proves my point:
"A conventional plug wire has a resistance of 10,000 to 15,000 ohms per foot of length--if it's measurably higher, the wire probably is bad."
Even a single fine thread of copper has far less resistance than that! The reason is that spark plug wires actually have a resistive element inside them to reduce EMI. No copper, but a carbon-based resistive element. So, spark plug wires have nothing in common with speaker wires!
The battery wires do share something in common with speaker wires and in fact just for grins and giggles I've wired up speakers with battery cables. I don't want to start a fad - it makes no difference because it is gross overkill. However they see an environment that is pretty horrific, including the potential to be doused with dilute sulphuric acid from the battery that they are connected to. Dilute Sulphuric acid dissolves a lot of things pretty quickly including skin and copper, and one irony is that dilute sulphuric acid is more corrosive than the pure concentrate.
As long as a speaker cable has a good mechanical and electrical connection at both ends, discoloration along its length means nothing.
They say corrosion is okay, it makes no difference? Don't think so. What is does is raise resistance, very, very slightly.
The corrosion on a speaker wire is very thin, and the material that copper oxidizes into namely copper oxide is somewhat conductive. Modern measurements are good enough that one should be able to measure the loss of conductivity due to mild corrosion such as we find indoors, but I've never done the experiment carefully enough to find a clearcut result. What I can tell you is that the corrosion is fairly easy to remove with find grit (say 220 grit) sandpaper and expose pure shiny copper.
Speaker wire is cheap.
It usually is, unless you buy it from audio stores. Back in the day you could easily find 12 gauge stranded wire for pennies per foot, but those days seem to be gone. Even hardware stores and big box home improvement stores have figured out how to improve their margins for good speaker wire.
But you make a point - if you don't like the looks of your speaker cable and you buy some nice 12 gauge from Monoprice or someone like them in a big spool, speaker wire is one of those things you can replace and not break the bank.
It can be more trouble to clean up the ends of oxidized speaker cable than it s worth. You can spend more on a pack of fine sandpaper to clean it up than it costs in bulk and for typical lengths.