Speaker wire problem

Discussion in 'Archived Threads 2001-2004' started by Dennis Heller, Oct 8, 2002.

  1. Dennis Heller

    Dennis Heller Second Unit

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    I use plain 12 ga. copper speaker wire from Home Depot, with Rat Shack bananas on one end and spades on the other. If I remember correctly, these wires were shiny copper color when I bought them. Now they seem to be dark gray, almost black, along the entire run of the wire (about 8 ft.). What would cause this? Is it possible this is normal?
     
  2. Ted Lee

    Ted Lee Lead Actor

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    it's more than likely just oxidation. i don't know about whether it has any sonic effect or not though - if i had to guess, i'd say it will not - but i'm not 100%.

    i've heard several people bring up this issue...especially with the home depot stuff.
     
  3. Chu Gai

    Chu Gai Lead Actor

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    The Home Depot wire is made by Carol and as far as what you're observing, this is the reply I obtained from them.
     
  4. Ted Lee

    Ted Lee Lead Actor

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    chu - so "technically" is this oxidation or some other phenomenon?
     
  5. RichardMA

    RichardMA Second Unit

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    For people using second-rate speaker wire from outfits like
    Home Depot; Many of these have three problems;
    1. The jackets are not gas-tight, so the copper oxidizes.
    2. The copper reacts to the outgassing from the cheap PVC jacket and it oxidizes to malachite (the green stuff).
    3. The copper is coated with a lubricant that prevents good conduction compared to "clean" copper.

    Do yourself a favour; Find a source for surplus wire, locate some silver plated, teflon jacketed wire and make
    up your own speaker cables. A friend of mine found some
    that was 12 guage and he paid all of $25 for 250ft.
    Of course new you would pay a fortune for it.
    Chuck two lengths of it in a drill, and run it until you
    have it fully entwined.
    This stuff will wipe the floor with any of that Far Eastern-made junk being sold by Home Depot or other cut rate supplier.
     
  6. Ted Lee

    Ted Lee Lead Actor

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    richard -

    is there a special technique when winding wire in a drill chuck? i've tried it a couple of times, but my wire keeps winding "funky"...it like bends and twists all weird. it never seems to do it cleanly.
     
  7. Chu Gai

    Chu Gai Lead Actor

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    technically there are probably a multiplicity of effects occuring. the green color is due to either pvc degradation and/or the presence of unreacted monomer in the polyvinylchloride. PVC, by itself, will degrade with increasing temperature. To offset this, additives are incorporated into the finished product such as plasticizers, pigments, etc. The type and concentration act to increase the thermostability of the plastic. From what I can tell, this appears to be a surface pheonomena and one wouldn't expect much difference in reacitivity if the copper is OFC, 3 nines, 7 nines, 'single crystal', etc. As far as teflon goes, it certainly is more thermostable although flexibility, keeping sizes comparable to say PVC, is much worse. Teflon is also gas permeable so while one won't have the effect of the formation of copper chloride, surface oxidation due to reaction with oxygen, or for that matter exposure to any sort of atmospheric pollutants such as suflides will also permeate through the teflon. Again though, its a slow process and is a surface phenomenon. Of course, if the plastic covering the wires is colored or opaque then one doesn't see what's going on underneath. For some, it's out of sight out of mind. The fact remains though, that however pure your wire is and regardless of what you have it sheathed with, there will always be a surface oxidation. Silver, copper, they'll all do it.

    For those interested in dropping $5 I believe it is, a reprint from the AES titled:
    "Effects of Cable, Loudspeaker and Amplifier Interactions", JAES Vol.
    39 No. 6
    might prove to be an interesting read.
     
  8. Ted Lee

    Ted Lee Lead Actor

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    good info chu - thx!
     
  9. Dennis Heller

    Dennis Heller Second Unit

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    Thanks for the help, everyone. I figured it could be oxidation, I just didn't realize the entire length of the cable would turn so quickly (less than a year). It doesn't seem to affect the sound, so for now I guess it'll be o.k. I'll just replace them somewhere down the road.
     
  10. Bill Kane

    Bill Kane Screenwriter

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    I think Chu is suggesting that it isn't oxidation, as we know it with bare copper, but a surface chemical reaction and fugeddaboutit
     
  11. Chu Gai

    Chu Gai Lead Actor

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    oxidation is oxygen. the green is reaction of copper with chloride to form copper chlorides.
     
  12. Dennis Heller

    Dennis Heller Second Unit

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    Ah, gotcha. It takes awhile, but eventually some information gets through. Thanks.
     
  13. RichardMA

    RichardMA Second Unit

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    To twist wire pairs using a drill;
    Chuck one end of the pair in the drill. Tie or attach
    the other end of the wire pair to some stationary object,
    water pipe in basement, whatever. Pull the wire until it's
    taut (sp?) and then run the drill. You'll feel the wire
    "shrinking" as it winds, but maintain the same tension.
    Once the windings look tight, release the wire from the
    drill. It will immediately coil around itself like
    some kind of snake. But, if you carefully unwind this,
    without bending the wire (silver coated copper conductors
    are often heavier guage than regular speaker wire so
    they can be bent) it will be perfectly relaxed and the
    twister pair wire ready to use as interconnect or
    speaker wire.
     
  14. Wayne A. Pflughaupt

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    Ted,

     
  15. Ted Lee

    Ted Lee Lead Actor

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    ahh...thanks guys! this forum is too cool for school.
    i think my main problem is that i wasn't keeping the tension as i ran the drill. i was too afraid that something would pull out from either the anchored end or the drill end.
    okay....now where did heck did i put my makita? [​IMG]
    thx again!
     

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