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Copper Speaker Wire Turned "Green"

post #1 of 18
Thread Starter 
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.
post #2 of 18
It is just oxidation and it should make no difference in effectivness. Don't worry about it
post #3 of 18
Quote:


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.

1) it's a reaction between the copper and the sheathing material which is typically PVC.
2) it's caused because over time and exposure to environmental variables such as temperature, the PVC degrades to form hydrogen chloride as one of the decomposition by-products. The reaction product, copper chloride, is green.
3) it has nothing to do with sealing the ends. if it bothers you tremendously, source out speaker wire that uses polyethylene, teflon, or similar insulating material.
4) it's largely a surface phenomenon that only goes down a few microns. If you're making bare wire connections (not to be recommended) then perhaps you can strip off some copper to get to some clean stuff and then terminate the ends in bananas or spades.
5) measuring the resistance of short pieces of wire is not all that easy or accurate. Now, if you had 500 feet...
post #4 of 18
Thread Starter 
Thanks!
post #5 of 18
I have the same problem with 2 pairs of wires (bi amped a pair of Infinity Servo Stats panels) that I bought 25+yrs ago. Total well over 150'. These were bought from a high end audio store that sold Monster Cable on a 500' or 1000' reel, look like 10 gauge also. They just cut off the lenght that you needed. Both ends were sealed and I couldn't figure out why they turned green, thanks for the info. Now I have connect to them up (yes the speakers still work with the sub) to see how they sound.
post #6 of 18
Next time you're in an antique store, look at the wires attached to the lamps.
post #7 of 18
Quote:
Originally Posted by will95 View Post

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. They say corrosion is okay, it makes no difference? Don't think so. What is does is raise resistance, very, very slightly. Speaker wire is cheap.
Bring it on guys, I know some of you can't resist.
post #8 of 18
Quote:
Originally Posted by Nuthed View Post

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. They say corrosion is okay, it makes no difference? Don't think so. What is does is raise resistance, very, very slightly. Speaker wire is cheap.
Bring it on guys, I know some of you can't resist.

Real audiophiles would chide the OP for not spending >$40/ft on his cables in the first place.

If replacing green cables makes you feel better, you will likely hear an improvement.
post #9 of 18
Quote:
Originally Posted by ericgl View Post

Real audiophiles would chide the OP for not spending >$40/ft on his cables in the first place.

If replacing green cables makes you feel better, you will likely hear an improvement.

Why? Do $40 per foot speaker cables not corrode?
post #10 of 18
See post #3, but that was not my point. Here is a clue, I consider myself to be the anti-audiophile.
post #11 of 18
Well, an anti-audiophile must use anti-cables! Maybe you're just a pragmatic enthusiast
post #12 of 18
Seeing as the corrosion only goes down a few microns, you'd be hard pressed to measure any changes in resistance. If it does bother you, and there's no reason why it shouldn't, just replace it. OTOH, you may simply not look at is as corrosion, but the development of a patina
post #13 of 18
Quote:
Originally Posted by ericgl View Post

See post #3, but that was not my point. Here is a clue, I consider myself to be the anti-audiophile.

You explained in post #3 why you believe copper corrodes over time, I have no reason to doubt those reasons, but now try to prove it doesn't make a difference.
Eventually that build up will cause loss of contact, in my opinion.
post #14 of 18
That would depend if the ends of the wires were terminated by soldered connections, a good cold weld, or bare, no? To a large extent, the surface corrosion on the wire (under the PVC) acts as a barrier to further attack. As an example, find the nastiest old penny you've got laying around and give it a quick rub with an anti-tarnish product. Back to copper, right?
post #15 of 18
Quote:
Originally Posted by Chu Gai View Post

Maybe you're just a pragmatic enthusiast

Now I could be comfortable with that stereotype.
post #16 of 18
Quote:
Originally Posted by Chu Gai View Post

Well, an anti-audiophile must use anti-cables! Maybe you're just a pragmatic enthusiast


Hey, that's supposed to be good stuff!

http://anticables.com/products.html

But actually if one is interested in that sort of thing, just go down to your local motor rewind shop and ask for magnet wire.

I have wild pets roaming my HT; I use chew proof wire.
post #17 of 18
Yes, I know. Old thread.

I had a spool of the infamous 12ga GENERAL clear speaker wire from Home Depot.

The entire length of the copper colored side has turned green.
There appears to be zero corrosion on the silver colored side.

Interesting that it has only turned green where it is covered with the pvc jacket. All the stripped ends including the ones terminated in
banana jacks are still a bright copper color after 10 years. So, cutting the wire back actually forces you to use the corroded wire. Yes, the corrosion
is only a very thin surface layer. I tried cleaning it with battery post cleaner as well as contact cleaner/restorer. The contact cleaner worked pretty
well but I am sure there is something better.

This is obviously a design defect that causes the cable to fail. I am replacing 500' of cable. It would be nice if Home Depot or General
would step up and stand behind their product the way Monster did.

I guess you get what you pay for.
post #18 of 18
Quote:
Originally Posted by Nuthed View Post

Quote:
Originally Posted by will95 View Post

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:

http://www.popularmechanics.com/cars/how-to/maintenance/1272351

"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.
Quote:
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.
Quote:
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.
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