DIY speaker cables

Discussion in 'Archived Threads 2001-2004' started by Jeremy Hopkins, Oct 15, 2002.

  1. Jeremy Hopkins

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    I know there is a bunch of sites with how to make CAT5 etc. but during one of my labs today I saw some cable that peaked my interest. It was Belden cable, I looked up somethings and I think it is Plenum Computer Cable. The part number I was looking at was 82509. It has 9 pairs of a color and a black wire, plus its shielded.

    Would this be good for speaker cable? I'm just curious. I'm looking for something that has a low capacitence because I have a crappy amplifier. I'm also looking for something good to be able to put inside my speakers, when they are ready.

    Cheers,

    Jeremy
     
  2. Bill_Weinreich

    Bill_Weinreich Second Unit

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    Jeremy,
    I've seen ribbon cable used like these , so I don't think you should have much of a problem. Keep in mind the total capacitance will increase as you pair the wires together.
    Bill
     
  3. Jeremy Hopkins

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    Ok, my knowledge of electronics is alright. I did my first two years of my degree in EE so I know a litle bit, but am very veyr very far from an expert. Is there anyone who can explain capacitence in cables to me. Or show me to a sight that can.

    I might wait until next summer when I can afford a new amp. I don't want to wreck my amp by using the cables. I have an old Technics Su-V95 right now, I'm hoping to upgrade in the future(summer).

    Thanks

    Jeremy
     
  4. Bill_Weinreich

    Bill_Weinreich Second Unit

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  5. Jeremy Hopkins

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    How does the capacitence increase when the cables are linked. I was thinking of connecting all the colored cables and all the black cables. I remember seeing an explination to this somewhere, I just can't rmember where.

    I know that all cable has some capacitence over it's length; but what increases this?

    regards,

    Jeremy
     
  6. Bill_Weinreich

    Bill_Weinreich Second Unit

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    Double post.
     
  7. Bill_Weinreich

    Bill_Weinreich Second Unit

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    Any two wires side by side with a dielectric between them (the insulator/jacket) will in effect become a capacitor. Connecting all the colored cables and black cables will be like having nine capacitors connected in parallel. Caps in parallel are figured by Ct = C1+C2+C3+etc... Caps in series are Ct = 1/(1/C1+1/C2+1/C3...)
    Capacitence in cable increases in lenght because it's basically just a larger capacitor. More conductor and dielectric allows more energy to be stored. i.e. 23 pfds per foot will be 230 pfds at ten feet.
    Bill
    P.S. I'm not an expert either. Just a hobby [​IMG]
     
  8. Jeremy Hopkins

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    Ok, I think I get the idea....
    Thanks a lot....I may have more questions, but they will have to wait for tomorrow.
    Cheers,
    Jeremy
    PS. Hobbies are great aren't they [​IMG]
     
  9. Jeremy Hopkins

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    When I connect some of the wires together, will that increase the capacitence per foot? Is there a way to calculate this? I'm a little bit away from being able to build my speakers and want to put some nice cable inside them. There would be short lengths (1ft or so) so capacitence should be that high. Would this affect my amp at all? It would still be a small amount?

    Thanks

    Jeremy
     
  10. Bill_Weinreich

    Bill_Weinreich Second Unit

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    Jeremy,
    Calculation in a perfect world would be easy, but tolerences in bundled cable can vary. Wires won't stay the same distance from each other (especially when flexed) and that can cause a capacitence change. Normally though it's not bad enough to worry about. According to Belden, capacitence on the 82509 is 23 pfds per foot. I will assume this is measured per twisted pair. 9 pairs has 207 pfds per foot. Multiply that by total footage( i.e. ten feet = 2070pfds.). Best bet would be to buy (or better yet borrow) a DMM with capacitence and build a set to test.
    Bill
     

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