Wire Length really that much difference?

Discussion in 'Archived Threads 2001-2004' started by Anthony Lengyel, Jan 31, 2003.

  1. Anthony Lengyel

    Joined:
    Jan 28, 2003
    Messages:
    25
    Likes Received:
    0
    Ok I was told by my home theater dealer that you should make the wires to the fronts and center all the same length. He contiunued to explain about something of the human ears can detect upto 15ms delay or something..

    Now I guess my question is this true? Before I wired up my speakers long enough to reach them..

    i.e. Front right 6 feet
    Frnt Left 10 feet
    Center 3 feet

    So what he is saying that I should wire all 3 up with 10 feet lenghts. Is this true?
     
  2. Patrick Sun

    Patrick Sun Moderator
    Moderator

    Joined:
    Jun 30, 1999
    Messages:
    38,678
    Likes Received:
    439
    Maybe if the differences were in terms of hundreds of feet, it might make a sonic difference.

    But for your own personal peace of mind, perhaps using the same lengths would do you good.
     
  3. RayJK

    RayJK Stunt Coordinator

    Joined:
    Nov 25, 2002
    Messages:
    131
    Likes Received:
    0
    186,280*5280=983558400fps therefore 1ft takes 0.0000000010167164 seconds, 7 ft difference would be 0.0000000071170151 seconds. I doubt you can hear this.
     
  4. Edward J M

    Edward J M Cinematographer

    Joined:
    Sep 22, 2002
    Messages:
    2,031
    Likes Received:
    0
    In a typical HT set-up, the length of decent grade 14 gauge or 12 gauge speaker wire will have absolutely no sonic impact with respect to time delay or resistance.

    If you have VERY long runs, definitely use 12 gauge to minimize resistance build-up. Other than that, don't worry about different length runs causing time delays - that's simply ridiculous and patently untrue.

    The time delays you can program into your digital processor for speaker distance to the listener are several orders of magnitude higher than any time delay caused by one speaker run being a few feet longer than the other. Good grief - find another dealer - who knows what else he has been telling you! :b

    Regards,

    Ed
     
  5. Doug BW

    Doug BW Stunt Coordinator

    Joined:
    Nov 27, 2001
    Messages:
    141
    Likes Received:
    0
    Sound moves through the air about a million times slower than an electrical signal moves through a wire.

    So if the wire to your left speaker is a foot shorter than the wire to your right speaker, merely move your head one millionth of a foot to the right to compensate.
     
  6. Anthony Lengyel

    Joined:
    Jan 28, 2003
    Messages:
    25
    Likes Received:
    0
    "So if the wire to your left speaker is a foot shorter than the wire to your right speaker, merely move your head one millionth of a foot to the right to compensate.
    "

    Hahaha I like that.
     
  7. TimTurtino

    TimTurtino Stunt Coordinator

    Joined:
    Dec 17, 2002
    Messages:
    156
    Likes Received:
    0
    2 things--

    Speed of signal in a wire isn't speed of light. Not that it's that much slower, but just saying...

    I _believe_ that the reasons people give for having wires that are the same length (and rears wires that are multiples of the lengths of the fronts) has more to do with resonances than speed of signal through the wire. While I still personally think this is bunk (my rears are 43' and 57' respectively [​IMG] ), it's at least a little more believable bunk.

    Me
     
  8. John Royster

    John Royster Screenwriter

    Joined:
    Oct 14, 2001
    Messages:
    1,088
    Likes Received:
    0
    It has nothing to do with speed/delay and everything to do with the effect the wire has when joining speaker and amplifier. The wire can indeed change frequency response depending on length, amplifier, speaker, wire.

    Ideally keep the front three channels the same length to balance any changes the wire may induce. If less than ideal is OK, then use any lenght necessary.
     
  9. Scott Falkler

    Scott Falkler Second Unit

    Joined:
    Oct 23, 2001
    Messages:
    442
    Likes Received:
    0
    First,make sure your wires are the same length.
    Next,make sure you turn off the heater/AC and any fans that may make noise.
    Also make sure it isn't windy or raining outside as you may hear it and it will detract from your experience as well.
    Sit directly in the middle and DO NOT turn your head as the sound will degrade many orders of magnitude. Bass will sound bloated and heady, the midrange will be stoked and defunct, and the high frequecies will be party cloudy with a chance of precipitation.
    Don't forget to make those speaker wires the same length!!!
     
  10. Mat_M

    Mat_M Stunt Coordinator

    Joined:
    Jan 3, 2003
    Messages:
    225
    Likes Received:
    0
    If making your speaker wires the same length makes you feel warm and cozy inside that's fine. But here's a link that will tell you the straight up truth about speaker cabling:
    http://home.earthlink.net/~rogerr7/wire.htm

    I work in an engineering lab and can tell you that a speaker wire can be viewed as a simple transmission line model. Since we are dealing with frequencies between 20Hz and 20kHz (very low), parasitic capacitance and inductance play a SUPER minor role in terms of signal loss. As long as you have a nice 14 or 12 gauge wire, the difference between speaker wire length can be huge. The misconception people mix up is the fact that actual electrons move along a wire at a VERY low speed (http://www.amasci.com/miscon/speed.html). However, view electrical current as a hose with water -already- in it: When you turn on the water at one end, it's pretty much instantaneous that water comes out the other end. The speed of electricity is VERY close to the speed of light in a vacuum (1/3*c).

    Now assuming what your sales rep said is true (15ms time delay)...This would require a difference of 4,917,855 feet of wire between the two speakers. So from a technical viewpoint, you'd be perfectly fine with different wiring lengths.
     
  11. John Royster

    John Royster Screenwriter

    Joined:
    Oct 14, 2001
    Messages:
    1,088
    Likes Received:
    0
     
  12. Mat_M

    Mat_M Stunt Coordinator

    Joined:
    Jan 3, 2003
    Messages:
    225
    Likes Received:
    0
    1-2 dB in how much difference of lengths? 3000 feet??? If you're loosing 1-2 dB in a length running from your receiver to your speaker, get yourself some new speaker wire.

    Here's something to put into perspective: On the very last slide of this presentation (http://www.ul.ie/~rinne/ee6471/ee6471%20wk9.pdf) is an example of an electrical pulse sent through 24AWG wire for a distance of 1km. The loss here is about 1-2 dB, but we are talking about 24AWG wire, which is TINY compared to 14 or 12 gauge wire; and on top of that, the length is 1000 meters. A square pulse like this, when changed through a Fourier transform, yields a sum of frequencies far higher than 20kHz.

    So please explain to us how you will loose 1-2 dB in 14 or 12 gauge wire running from your receiver to your speaker.
     
  13. TimTurtino

    TimTurtino Stunt Coordinator

    Joined:
    Dec 17, 2002
    Messages:
    156
    Likes Received:
    0
     
  14. John Royster

    John Royster Screenwriter

    Joined:
    Oct 14, 2001
    Messages:
    1,088
    Likes Received:
    0
    Mat,

    The problem with that presentation is there wasn't a speaker attached to it. [​IMG]

    I'll let the other EEs explain what happens at 20Khz on a speaker that presents a less than 1 ohm load. I graduated way too long ago to remeber EE201. All digital for me now.
     
  15. Steve Zimmerman

    Steve Zimmerman Second Unit

    Joined:
    Dec 6, 2001
    Messages:
    347
    Likes Received:
    0
    John, OK I have a Master's Degree in EE and I'll chime in to say that what you're describing is inaudible.

    --Steve
     
  16. John Royster

    John Royster Screenwriter

    Joined:
    Oct 14, 2001
    Messages:
    1,088
    Likes Received:
    0
    So a few db of attenuation is inaudible? It always has been for me.

    Another member BruceK was kind enough to enlighten me as to how cable lengths can affect high frequencies by looking at the whole system instead of just a wire. Oh well, its not worth arguing over. To each his own I guess.[​IMG]
     
  17. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
    (So why isnt this thread in "tweeks and connections"?)

     
  18. Julio Ortiz

    Julio Ortiz Agent

    Joined:
    Jan 22, 2003
    Messages:
    28
    Likes Received:
    0
    .
     
  19. Steve Zimmerman

    Steve Zimmerman Second Unit

    Joined:
    Dec 6, 2001
    Messages:
    347
    Likes Received:
    0
    John, I'm saying I don't believe a 20ft length of normal 12 guage wire attenuates the audible range of frequencies by even 0.05 dB.

    That's my opinion--for now, but I'll measure it just for fun.

    --Steve
     
  20. Mat_M

    Mat_M Stunt Coordinator

    Joined:
    Jan 3, 2003
    Messages:
    225
    Likes Received:
    0
    Maybe there's been a misunderstanding here: 1-2dB of attenuation means loosing between 21% and 37% of your power. I am positive that this will not happen in 14 or 12 gauge speaker wire between the frequency range 20Hz to 20kHz, running from your power source to your speaker. Can you imagine how hot the wire would get if you lost that much power in it?

    John, now if what you're referring to is the actual wire+speaker combo impedance curve, then we're talking about something entirely different.
     

Share This Page