Speaker distance set up ?

Discussion in 'Archived Threads 2001-2004' started by Jerry AZ, Jan 17, 2002.

  1. Jerry AZ

    Jerry AZ Stunt Coordinator

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    I posted this in the Speaker section, but didn't get many hits. Thought I'd try in the main section. [​IMG]
    Is there a rule of thumb for setting speaker distance when it is between settings? I have my center speaker at 9.5 feet. Should I set it up in the receiver as 9 feet or 10 feet?
    Also, should the center and fronts be the same distance? My front mains are at 10 feet, center at 9.5 feet to be flush with the front of my entertainment center.
    Thanks.
     
  2. John H

    John H Second Unit

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    Ideally all channels speakers should be the same distance from the listening position. This is not always practical.
    You proccesors speaker distance setting will compensate for discrepancies by adding delay to the channels signal.
    As far as your center channel speaker position. I would not compromise it's performance by moving it back beyond the front of your entertainment center. If possible I would suggest even overhanging the front somewhat.
    John
     
  3. Bob McElfresh

    Bob McElfresh Producer

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    Short Answer: this setting is a third/forth order adjustment -meaning that it is of minor importance. So dont worry about 0.5 feet adjustments in the time delay. Just pick the higher/lower number.

    Long Answer: A PsychoAcoustic study on time delays between 2 sounds discovered something called the "Hass Effect".

    (This is what the time delay/speaker distance setting is trying to do: compensate for sitting a different distance from each speaker)

    What they found was that if the same sound originated from 2 sources at different times, the time delay caused different perceptions:

    0-5 miliSecond delay - Human perceived 1 sound source

    6-11 miliSecond delay - Human somtimes thought 1 source, sometimes thought it was 2 source

    12-xx miliSecond delay - Human percieved 1 sound source, but thought the source was several feet farther away than it really was.

    So for setting the speaker distance in our home theater system, you have to be off by more than 5.5 feet before your ears can detect a problem. (Using the formula that sound travels 1.1 feet per miliSecond in your living room, except in Denver)

    So your setting of 9 feet vs 10 feet makes little difference.

    Does this help?
     
  4. Jerry AZ

    Jerry AZ Stunt Coordinator

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    Thanks guys. I was just wondering how big an efect it would have. My center is actually closer to 9 feet, so I'll set it at that.

    Interesting though; I was playing a music CD today and switching between 9 and 10 feet, I could tell some difference.

     
  5. Bob McElfresh

    Bob McElfresh Producer

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    Placing the center speaker on a TV is a little tricky. It is usually a good idea to put "feet" under center speaker so it does not acoustically couple itself to the TV cabinent. Small wooden dowels, pink-rubber erasers, rubber door wedges, even paper-back books have all been used. The rubber door wedge also gives a nice downward tilt towards the listening position. (I have a half-inflated wheelbarrow innertube under my center speaker: an $8 tweek.)

    If the speaker is pushed back, there is a little shelf in front that will reflect sound waves upward causing some distortion.

    If the speaker is flush with the front of the TV, this can couple the face of the speaker with the front of the TV causing some distortion.

    Pulling the face of the center speaker forward about 1/4 inch is all you need to do to break the plane. (Think of water dripping off the front of the center speaker - you want the drops to NOT smear down the TV face).

    The net effect of doing all this with my DefTech center was a slight reduction in some fuzz/distortion. So this is a minor adjustment, but not hard or expensive to do.

    Hope this helps.
     
  6. Jerry AZ

    Jerry AZ Stunt Coordinator

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    Thanks Bob, I'll try that out and see if it makes any difference.
     

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