SPL loss based on distance from speakers?

Discussion in 'Speakers' started by Lee-c, Nov 22, 2003.

  1. Lee-c

    Lee-c Second Unit

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    If I recall correctly, the standard rate for loss of SPL is 6dB for every doubling of the distance
    from the speakers past the first 3 feet where the sensitivity rating is measured. But I think
    I remember reading that ribbon drivers lose less of their SPL output over distance than do
    cone drivers. If that is the case, I was wondering if any of you fellows know what is the SPL
    loss rate per doubling of the distance from the speakers for ribbon drivers?

    Thanks for any info. [​IMG]
     
  2. RichardH

    RichardH Supporting Actor

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    It's not ribbon drivers per se, but rather line sources. They only lose 3 dB per doubling of distance. Magnepan are a common example of line source speakers. But you can have line source speakers using other methods. e.g. Martin Logan electrostatic panels. Or just a huge vertical array of cones and domes!
     
  3. Lee-c

    Lee-c Second Unit

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    RichardH: Ah, I see. And how many drivers of the same type need to be stacked to get this "line source"
    SPL effect you mentioned (assuming the speaker isn't using one giant ribbon or panel); 2, 3, 5?
     
  4. RichardH

    RichardH Supporting Actor

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    Not sure about that. I would imagine you get more of the effect as you add drivers, but there's probably not a hard and fast rule as far as how many drivers gets you to a line source.

    That being said, for the cone and dome type line source speakers, it seems like you either have a ton of drivers (like 16 or more) or you just have the normal 2-way or 3-way design, not a lot of middle ground.

    In the end, I don't think it should be a reason to pick one speaker over another, although line source speakers do have a kind of sound, and you may like that over "regular" speakers.
     

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