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  1. #1
    thylantyr's Avatar
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    Exotic Speaker Wire

    I've noticed alot of people on forums jumping on the CAT5 speaker wire
    bandwagon. They are taking networking wire and making into speaker
    wire as they think it's superior.

    To make matters worse, these guys did a wire test;
    http://www.audioholics.com/techtips/...rCablesp1.html

    This test is misleading to the consumer as they rank cables implying that
    certain brands aren't good as speaker wire.

    I did some basic electronics math to see what the skinny is all about.

    Wire has resistance, capacitance and inductance. They measured those
    variables and formed a conclusion. But there is more to the story than
    what was told. How does the particular wire perform in it's 'line driving'
    application ?

    How much resistance, capacitance and inductance is ok before your
    speaker wire behaves like a low pass filter which will attenuate the higher
    audio frequencies? We can look at wire gauge and know it's current
    ratings per foot, so I don't need to talk about this as we already know.

    Preamp Line Driving
    This Rane article "Practical Line-Driving Current Requirements" is a good read.
    http://www.rane.com/note126.html

    It talks about small signal line driving {preamp level}, but the same is true
    for large signal line driving, ie amplifier to speaker.

    Look at figure 2.

    Ro = Source output impedance
    Cw = Total cable capacitance
    RL = Input impedance of the load.

    Look at figure 3. The formula.

    You use this to analyze your signal path, either preamp or power amp.

    For instance, lets say you bought some cable to make your own RCA
    or XLR preamp cables. If you know the cable capacitance, source output
    impedance, and destination input impedance, you can see if that cable
    you chose will will in the audio range with no low pass filter effects in
    the audio range.

    Lets say your preamp is 100 ohms output impedance, and your amplifier is
    10,000 ohms input impedance and the cable you chose has a rating of
    50 pF {pico Farads} per foot. You decide you need a 100 foot cable.

    Math.

    Ro = 100 ohms
    Cw = 50 pF x 100 foot = 5000 pF {or 0.005 uF, or 0.000000005 Farads}
    RL = 10,000 ohms

    Because the Ro is significantly less than RL, you can use the short formula.

    Fc = 1 / (2 pi Ro Cw)

    Fc = 318 khz

    318khz is way higher than the audio range, 20khz so this cable would
    work in this application.


    Power Amp Line Driving

    Amplifier output impedance is very low vs. the speaker load. Amplifier damping factor gives you a clue on how low output impedance is. Damping factor is
    a ratio.

    DF = load / amp output impedance.

    or

    amp output impedance = load / DF

    If your amp has a damping factor of 100 {assume @ 20khz} driving an 8 ohm
    load, then the amp output impedance is about 0.08 ohms.

    Fc = -3dB point, cutoff frequency.
    Ro = 0.08 ohms
    Cw = 50 pF x 100 foot = 5000 pF {or 0.005 uF, or 0.000000005 Farads}
    RL = 8 ohms

    Lets use the same 50pF capacitance and lets say you are running a 100 foot
    speaker wire.

    Because the Ro is significantly less than RL, you can use the short formula.

    Fc = 1 / (2 pi Ro Cw)

    Fc = 379 Mhz


    This is way outside the audio range.

    Speaker Wire Inductance

    Speaker wire is like an inductor and when you connect your amplifier
    to speaker wire to the speaker, it's as if you are adding an inductor in
    series just like a first order woofer crossover.

    The math is simple.

    Fc = RL / (2pi L)

    Fc = -3dB point, cutoff frequency.
    L = cable inductance
    RL = speaker load

    The worse speaker wire of the bunch tested has an inductance of 0.3 uH
    per foot. Lets assume you are going run 100 foot between amp and speaker.

    L = 0.3uH x 100 feet = 30 uH
    RL = 8 ohm speaker

    Fc = 42.4khz

    This is way outside the audio range of 20khz


    Conclusion
    Unless I analyzed wrong, cable capacitance even using cheap cables doesn't play
    a big role in affecting the audio signal. Even cheap speaker wire with high inductance
    and a 100 foot run is still 2x beyond the audio range where you have low pass filtering effects.
    To add, inductance in preamp cables connecting to high input impedance equipment doesn't
    play a big role either.
    Last edited by thylantyr; 12-11-2006 at 05:47 PM.







  2. #2
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    Re: Exotic Speaker Wire



    long thread




  3. #3
    thylantyr's Avatar
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    Re: Exotic Speaker Wire

    Cost

    CAT5 vs. generic speaker wire

    I see two simple ways to wire up the CAT5. CAT5 is 4 pairs of conductors,
    24 awg each.

    1. Four conductors in parallel to make an equivalent 19 awg speaker wire
    run. This gives you two conductors per cable run, 19 awg each. 19 awg
    is a little anemic as most people prefer to over-engineer their wiring needs
    and run 14 awg - 16 awg wires from amp to speaker and heavier awg for
    subwoofer runs. Depends on length of run, etc. I personally wouldn't wire up
    my house with 19 awg speaker wire. I would use 18 awg for wiring up
    the drivers inside a speaker box as the runs are short in length.

    2. ALL eight conductors in parallel to make an equivalent 15 awg speaker wire
    run. This only gives you one conductor so you need to run two seperate
    CAT5 cables for each speaker. What a PITA if you are wiring up your home.

    Cost:

    500 foot CAT5 cost $60
    1000 foot CAT5 cost $120

    500 foot 18 awg generic speaker wire cost $60
    500 foot 16 awg generic speaker wire cost $80

    If you chose option 1 above for your application, then there is no cost
    advantage to buying CAT5. Two conductor CAT5 wired for stereo would
    yield 19 awg speaker wire. You can buy generic speaker wire 18 awg
    for the same price.

    If you choose option 2 above for your application where you use CAT5
    to make a single 15 awg cable, then you need 2x more cable as you
    need two cables per speaker vs. generic 16 awg speaker wire. Cost
    $40 for CAT5 plus you have 2x more cables to run, more messy.

    If I'm wiring a long run from amplifier to speaker, lets say a few hundred
    feet, then I would now look at speaker wire inductance and do the line
    driving math to see if the low pass filter is outside the audio range, etc.




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    Re: Exotic Speaker Wire

    Wal-Mart speaker wire works for me.




  5. #5
    RaiN's Avatar
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    Re: Exotic Speaker Wire

    ^Shizzle




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    Re: Exotic Speaker Wire

    ok




  7. #7
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    Re: Exotic Speaker Wire

    cool.



    References:
    Caraudio.com
    Luckyt,Hotown,Thunder9500,Vladd,Mikeyb,kngoftheprk nglot, cd6551(x3),bolognabake,dalucifer,phrozen5100, frito,bring97, avs20,Resonant18,djman37,Showrides,Fi car audio(X2),jeeper07(x2),pimpedout97x,matrxx dude(x3),flakko(x2),mega1268,powernaudio,iamamp3pi mp.bamaboy,Daishi(x3).angrytrucker78,impalafan95.n etherland, down,blue200sx(x2),QtrHorseThecybe,jiggy2dmax,stc1 709,musclehead,NDMstang65v2,alxmlr789
    Carstereos.org
    Wackii,BrownNoiseBob
    Explorer4x4.com
    Fordexplorer157
    Mp3car.com
    StLB5,Coolskys05
    I know there is more ill try to find them.

  8. #8
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    Re: Exotic Speaker Wire

    The reason I like to hang out in car audio forums is because the older
    crowd as found on dedicated home audio forums starts to lose their mind.
    Lucky me, I'm still immune to this effect as I age - LOL......

    All of a sudden, things that have been working for ages no longer works anymore and you need esoteric audio items like DIY CAT5 speaker wire
    with a million braids, rocks in a jar, $500 AC power cord, etc., to make it sound
    good again... ROFL ...

    In car audio, people tend to keep an open mind and use more common sense.




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    Re: Exotic Speaker Wire

    ok.




  10. #10
    thylantyr's Avatar
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    Re: Exotic Speaker Wire

    Check out the article I linked, generic Sound King wire was tested,
    4 versions from standard to esoteric braiding. All the braided versions
    tested for higher inductance {worse} than the standard un-modified wire. lol




  11. #11
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    Re: Exotic Speaker Wire

    pear cables
    http://www.pearcable.com/
    speaker wire for $7.50 per foot



    1995 Honda Acord LX Sedan

    Headunit- Pioneer Premier DEH-770MP, linked to iPod
    Front Stage- Crystal Mobile Sound SSX series 6.5"
    Rear Stage- Crystal Mobile Sound SSX series 6x9
    Subwoofer- Diamond Audio D6 12" sealed
    Subwoofer Amp- Audiobahn A8000t 1500watt w/ 1.0 farad stiffening cap
    Wiring- KnuKonceptz 2gauge
    To Come: Two Fi BL15s, Diamond Audio D6 2000.1 amp.
    box: undecided

    AIM SN- ivrex

  12. #12
    PV Audio's Avatar
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    Re: Exotic Speaker Wire

    I have trouble understanding how cables can be "accurate". Bullshit.




  13. #13
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    Re: Exotic Speaker Wire

    Quote Originally Posted by PV Audio View Post
    I have trouble understanding how cables can be "accurate". Bullshit.
    But if you've got the money, who cares?



    Kicking the tires, Lighting the fires.

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    Re: Exotic Speaker Wire

    Dielectric Absorption is another audiophile's weapon to justify the voodoo wire.

    Don't take my word that this is also a bag full of donkey doo, these guys say
    the same thing.

    Debunking the Myth of Dielectric Absorption
    http://www.audioholics.com/techtips/...bsorption.html

    It's pretty bad to engage in amplifier ABX testing, but it's really ridiculous
    when people *really* believe they can hear a typical run {lets say < 100 foot}
    cable.

    But on the other hand, as you can see from the math, one *can* make a bad cable
    that will act like a filter in the audio band, but no manufacturer in their right mind
    would even make such a product. lol




  15. #15
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    Re: Exotic Speaker Wire

    Well durr.

    nG




    http://crunktimes.com/ct/
    nG - BSEE

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