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Speaker Cable Length

Discussion in 'AV Receivers & Amplifiers' started by Colger, Dec 1, 2001.

  1. Colger

    Colger
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    Anyone any views on Speaker Cable length.
    Many years ago I remember reading an article that suggested the cable lengths for l and r speakers should be identical.
    I must admit that I didnt have my Yamaha A1000 wired with identical lengths but take delivery of a Denon AVR3802 on Tuesday so thought I should ask the question above.
    Any views would be appreciated.
     
  2. DodgeTheViper

    DodgeTheViper
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    Hi Gerry ,

    I myself have the Denon 3802 , boy will you be pleased !

    On cable lengths , i keep L & R to the same length give or take, also with the surrounds the same length. For the centre you can have this which ever suits you. They are best at same lengths because the information passed to them is in relation to each other, and to do with timing etc.
    Does this pose a problem for you ?

    Kevin
     
  3. rigman

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    Russ Andrew who deals with the Kimber cable among other very expensive things recommends that it should be okay as long as one lenth is not more than twice the length of the other.

    His cables can cost a fortune so he probably can spend quite a bit of money on research of these types of questions.
     
  4. Colger

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    Guys, thanks for the response - Mozzer, it doesnt pose any problems for me to keep lengths the same and I am lucky in that there is about 18-24" under my lounge with an external door for access. Looks interesting in there as all equipment is in a rack (2 VCR, LD player, record deck and audio cassette unit) plus the 3802 on Tuesday, in the corner of the room with the TV in the centre of a long wall with the DVD and Sky box, all cables run under the lounge.
    Was using a Yamaha A1000 with 4 surround speakers, 2 main, centre and an active sub and am really looking forward to Tuesday's new arrival!!!!!
    Thanks once again guys.
     
  5. iwilson

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    I don´t see how the length can make any difference to timing. The signal is traveling at close to the speed of light down the cable (300,000,000m/s). You can do the math yourself but you will need to make one cable thousands of meters longer than the other to introduce an audible delay.

    I also can´t see how avoiding doubling the length of any other cable makes a difference since the wave length of audio frequencies are tens of kilometers long and transmission line theory doesn´t apply until you reach 1/30 of a wave length - at 20kHz this is 500m, much longer than any speaker cable run in a home enviroment.

    What is more important is getting your speaker positioning perfect as sound propagates through the air at a relative snails pace and one speaker further away could make a difference with regard to timing.

    At the end of the day why not just do an experiment and get your local shop to hookup even and uneven lengths in a demo room.

    Ian
     
  6. rigman

    rigman
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    You may be right I am not sure, maybe its recommended to enable them to sell more speaker cable. Sowing the seeds of doubt is enough for people to go for the safer option of identical lengths and hence spend more money.
     
  7. flunchy

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    I recently re-wired my system so that the speaker cables were neatly hidden around the edge of walls, etc. Due to a bit of miscalculation I didn't buy enough cable to make the front L/R cables the same length. Wired them up anyway and to my ears there was no difference in sound from when the cables were the same length.

    From the hazy recollections I have of my Physics degree iwilson has the right maths and rigman probably has the right reason why it is suggested to use the same length ;)
     
  8. mjn

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    as sound moves at around 300 metres per second......it's not going to make much difference, unless you have HUGE setup, like an open air concert..!!!
     
  9. iwilson

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    Yes, I personally agree although there are good reasons to spend time aligning your speakers. It's just that if people claim using unequal lengths of speaker cable produces timing problems when dealing with the speed of light, you can imagine the problems they'll encounter when dealing with the speed of sound.:D

    Ian
     
  10. Guest

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    Its nothing to do with the speed of sound. Speaker cables sould be the same lenth because of the cables resistance. If your have a 10meter cable one side and a 1 meter the other then the cables resistance is 10 times as much on one side as the other.

    The thory is this could damage the amp. It would also seem logical that this may alter the quality or tone of the sound (I dont Know).

    In an Ideal world I supose we would have ALL 5/7 speaker the same design and each cable would be the same lenth. But who lives it that world?

    So keep it real and try to get each Pair of cables the same lenth but dont sweat it if they are a little different.
     
  11. iwilson

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    I'm sorry but that just isn't true. There is no difference in the resistance of a copper cable 1m long vs. a cable 10m long or even 100m long. If resistance in copper increased at the rate you're describing electricity would have a very hard time going from your switch box to your equipment - never mind getting from the power station to your home. Get a multimeter and try yourself, I absolutely guarantee you won't see one tiny bit of difference.

    Ian
     
  12. chips

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    Typical resistance of 322/0.10mm speaker cable is 8.0ohms per km. = 0.008ohms/m. You would not measure this on an average multimeter, but 1m will have a resistance of 0.008ohms and 10m will have a resistance of 0.08ohms ie ten times the resistance.
     
  13. iwilson

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    And if I take 10mm of wire to a laboratory with sensitive enough instruments they may tell me that it has 10 times the resistance of a 1mm length of wire.

    I would have though it obvious that the measurements we were discussing involved whole numbers at least. Unless of course you think a difference of .072 of an ohm is likely to damage an amplifier.

    Ian
     
  14. Guest

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    Ok then whats your theory as to why speaker cables sould be the same lenth I refuse to belive its just some con.

    HC installers have the answer?


    If Im wrong I'd like to know If speaker cables NEED to be the same lenth as I've alway belived.

    P.S I was over in your contry for the first time in late September WOW I loved it.

    Loved AMSTERDAM not so keen on ROTTERDAM.
     
  15. iwilson

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    I think their are a few reasons. Human nature for one, even though logically we know it doesn't matter, the thought of the signal arriving a picosecond early may get under our skin.

    It's easier to sell if you have equal lengths (although it’s more expensive to buy). The high-end cable companies have a vested interest in encouraging Audiophiles to buy more of their product. And as most people don't have the time or interest to research the actual physics. It’s easy to get caught up in the pseudo science babble that accompanies many of the exotic cable companies claims. Many of their claims are correct scientifically - but do not apply for audio frequencies. When dealing with microwaves even the length of the traces on a PCB board can be problematic as the wavelength at these frequencies is measured in centimetres or less compared to hundreds of meters at audio frequencies.

    The best way to decide is to do a simple experiment - run one short length and get a friend to randomly swap between the two, without letting you know which is which. Try and guess which is which. 20 or so repetitions should be a large enough sample. The changes should be completely random not short long short long.

    If you main concern is damage to the amp rest assured this will not occur. My Martin Logans and Rotel amp are living proof that unequal lengths will not cause any damage.

    At the end of the day all the fundamental properties of electricity are well understood and have been since the 30's. All electronic components are based on these theories and if they were wrong your toaster wouldn't work let alone your hi-fi.

    Ian

    Glad you enjoyed Amsterdam, something for everyone there! Rotterdam got flattened in WWII - did you see the cube houses?
     
  16. Guest

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    No(not until I got back to the UK were every program I see seems to be about the things I missed in the Netherlands) me and my companions walked down one of the streets looking for a coffee house. But the local hard drug uses made us a little nervious so we conducted or business and legged it.

    Utrect and some of the other towns were very prity and far more discret but AMSTERDAM was FUN.


    I SHALL RETURN.
     

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