Hi,
I'm not sure but I suspect it's some aging reaction of the clear polyvinyl jacket. Whether or not that is triggered by oxidation, I just don't know. What puzzles me is how the copper could oxidize beneath the jacket unless somehow oxygen got into the wire beneath the jacket during the coating process.
Virtually all copper speaker cable is sourced from China so it may vary depending on the vendor's source. I mean, why is our Axiom speaker cable super flexible whereas the SoundKing stuff I got ages ago from Parts Express is definitely stiffer. Maybe the latter doesn't have as many strands.
I remember when we introduced the Axiom generic speaker cable, someone at our Dwight factory counted the strands, and it has 275 strands per conductor.
Alan
