Should rear surrounds both have same length of wire?

Discussion in 'Beginners, General Questions' started by Johnny H, Feb 12, 2004.

  1. Johnny H

    Johnny H Auditioning

    Joined:
    Jan 11, 2003
    Messages:
    4
    Likes Received:
    0
    Will it make any conceivable difference to the human ear if one wire is 30 feet while the other is 45? Or should I make them both 45 to avoid any possible delay through the longer one?

    I don't imagine you could tell but I thought I'd ask BEFORE cutting that stuff up. [​IMG]
     
  2. Nathan Stohler

    Nathan Stohler Second Unit

    Joined:
    Jan 17, 2004
    Messages:
    329
    Likes Received:
    0
    I don't think you'll be able to tell the difference. Even if you could, it wouldn't be because of a delay. It would be because the speaker with the shorter run of wire was getting more power.

    I think [​IMG]
     
  3. Lew Crippen

    Lew Crippen Executive Producer

    Joined:
    May 19, 2002
    Messages:
    12,060
    Likes Received:
    0
    No.

    Plus don’t worry about any power difference. If there were any (and there will be no discernable loss over five feet) proper calibration of your speakers using a SPL meter will result in the same sound level output from all speakers.
     
  4. Boka

    Boka Stunt Coordinator

    Joined:
    Jul 29, 2002
    Messages:
    61
    Likes Received:
    0
    Saw a great post explaining this here once. Oh well, search and ye shall find. In short it said:

    (1) Electricity travels very fast, let's say that extra 15' of cable takes .00017 seconds for the electricity to surge down.

    (2) Okay, so the sound emits from once speaker .00017 seconds before the other. Can you hear the difference?

    (3) No. Sound travels very slow. In .00017 seconds, sound will travel about 2 inches. Ie. the net effect will be that the sound from one speaker will have a 2 inch lead on the other.

    (4) Since even leaning your head from one side to another is a movement of several inches (let alone sitting in a different position), you've probably never heard the exact same sound from both speakers at the same time anyway.

    (5) This is all just an example, I believe the time involved for electricity to move 15' is actually much less.
     
  5. Ted Lee

    Ted Lee Lead Actor

    Joined:
    May 8, 2001
    Messages:
    8,390
    Likes Received:
    0
    not quite...but it sure sounds logical. [​IMG]

    bottom line: nope, it doesn't make any difference.
     
  6. Greg Walker

    Greg Walker Stunt Coordinator

    Joined:
    Oct 21, 2003
    Messages:
    55
    Likes Received:
    0
    This may seem like a silly question, but if it doesn't matter that the wires are different lengths for the surrounds, why is it recommended that the front three speakers use the same length of wire? Is this just a myth as well?
     
  7. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0

    Yes. Often spoken by salesmen who make commission on expensive speaker wires.

    Measure your speaker wires to length. Then add a foot or two extra for maintance and so you can trim off the ends every year or so.

    If you have not finalized your speaker positions, add a few feet extra so you can move things around. But plan to cut them back once you have your final speaker positions set.
     
  8. Mike_Skeway

    Mike_Skeway Second Unit

    Joined:
    Jan 13, 2004
    Messages:
    265
    Likes Received:
    0
    With the short distance we use in our houses for speaker wire runs, there will be no difference if all are they are the same length or not. The length difference may be measured with instruments and you could figure it out mathematically, but we as humans will not notice anything.

    Don’t worry about the length, just give yourself a few feet of slack at each for the times that you need to move anything (speakers/rack) for any reason.
     
  9. Nathan Stohler

    Nathan Stohler Second Unit

    Joined:
    Jan 17, 2004
    Messages:
    329
    Likes Received:
    0
    Ted,

    I thought a longer wire would provide more resistance, so less power would make it to the speaker.

    --Nathan
     
  10. Lew Crippen

    Lew Crippen Executive Producer

    Joined:
    May 19, 2002
    Messages:
    12,060
    Likes Received:
    0

    There will be more resistance, and consequent power loss; in the few feet under consideration the difference is negliable.

    And even if the cable length differences were enough to create a discernable difference in power levels, calibrating your speakers with a test disk and a SPL meter, the calibration process results in adjustments that compensate for any differences in power, as the whole point of calibration is to get equal volume from all speakers when measure from the prime listening location.
     
  11. Ted Lee

    Ted Lee Lead Actor

    Joined:
    May 8, 2001
    Messages:
    8,390
    Likes Received:
    0
    reallY? i didn't think there was any at all. nathan - i stand semi-corrected! [​IMG]
     
  12. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0

    Last time I looked, the WORST resistance per foot of 16 ga speaker wire is something like 0.0182 ohms per ft. Trivial, but it does exist.

    And Lew is correct that level-adjusting with a SPL meter will compensate even if the resistance was much greater.
     
  13. Dave Schofield

    Dave Schofield Second Unit

    Joined:
    Sep 30, 1999
    Messages:
    401
    Likes Received:
    0
    Mike Knapp (is he around anymore?) used to have an entire webpage dedicated to this question. If I could only find it now...
     
  14. DanielKellmii

    DanielKellmii Supporting Actor

    Joined:
    Feb 5, 2004
    Messages:
    524
    Likes Received:
    0
    Electricity is energy, similar to light in many ways. (And in others, very different.) Over an ideal conductor, electricity travels at 186,000 miles per second. Add in the resistance, and it is a bit slower. Sound travels at 770 miles per hour in a room that is 70 degrees. (It depends on the temperature and density of the atmosphere, but for this discussion it doesn't matter. square root of(alpha x R x T)) So, 186,000 miles per SECOND is a lot faster than 700 miles per HOUR.
    With that being said, it doesn't matter to a human if the wires are different lengths. If you want, I can crack open a book and get out my calculator for a more detailed explanation but then I would have to get a bigger tattoo of "DORK" on my forehead.
     
  15. Mike_Skeway

    Mike_Skeway Second Unit

    Joined:
    Jan 13, 2004
    Messages:
    265
    Likes Received:
    0

    You got one of those too? LOL! [​IMG] [​IMG] [​IMG]
     
  16. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0

    Ok...you have to put this in terms HT people can understand:

    Sound travels 1.1 ft/mSec (This is how you set the time delay on many HT recievers.)

    Dork's are welcome, but Nerds rule! [​IMG]
     
  17. Nathan Eddy

    Nathan Eddy Second Unit

    Joined:
    Jan 22, 2004
    Messages:
    262
    Likes Received:
    0
    Electricity travels at the speed of light for an ideal conductor? That sounds impossible to me. Light travels that fast because photons have zero rest mass (otherwise, relativistic effects would increase their mass to infinity). But electricity is a flow of electrons, which do NOT have zero rest mass. So how can electricity move at the speed of light even for a theoretically ideal conductor? The mass of the electrons would approach infinity. I really don't think Daniel is right on this one point, but it's been years since I've had any physics classes, so I could be wrong.
     
  18. DanielKellmii

    DanielKellmii Supporting Actor

    Joined:
    Feb 5, 2004
    Messages:
    524
    Likes Received:
    0
    You are absoulutley correct. Now this gets a little weird. Electricity and electrons are not the same thing. Electrons are not really flowing, it is the wavefront that is flowing. It's like pushing caulk through a tube. The caulk goes slowly, but as soon as you push one side, it comes out the other. That is what electricity is like. Even this is a very simple explanation. It gets a lot more complicated, and I don't feel like digging out my old books and looking up Fermi Theory, The Consevation of Energy and something about Pauli.

    How does this end up in a forum about Home Theaters? Oy
     
  19. EricLThomp

    EricLThomp Auditioning

    Joined:
    Jan 16, 2003
    Messages:
    6
    Likes Received:
    0
    What is the best brand to get? Is Monster worth all the extra $$$$? What IS the best brand for great quality and not spending $100 per wire?

    Thanks!
     
  20. DanielKellmii

    DanielKellmii Supporting Actor

    Joined:
    Feb 5, 2004
    Messages:
    524
    Likes Received:
    0
    Do a search on this subject, it has been discussed before many times.
    My opinion is that Home Depot or Radio Shack is the best deal. I spent $200 on Monster Cable. For $50 I could have nearly the same think from home depot.
     

Share This Page