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    benefits of d'appolito

    What are the benefits of a d'appolito arrangement? Are the changes huge/drastic enough, to justify spending twice as much money on drivers? Is it possible to use higher older filters than 18dB with them and maintain the benefits?

    How much lower is distortion with a pair of drivers vs a single?

    Im assuming the drivers would have different diffraction patterns, since they occur on different parts of the baffle. Does different positioning of the drivers detract a lot from the speaker (as opposed to a single position where there is only one set of diffractions)?



    It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong. - Richard Feynman




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    Re: benefits of d'appolito

    You can probably google the 'd'appolito configuration' to see what the design
    goals are, a hit like so comes up.

    http://www.diyaudio.com/forums/showthread/t-14774.html

    You can also make a speaker that looks like an MTM but not follow the rules.

    I haven't seen any concrete evidence that TM, MTM, TMM is better over one another, there seems
    to be a personal opinion on what people like and too many variables that affect
    performance of each design. ie, you can make a great TM and lousy MTM and visa versa,
    the generic driver arrangement doesn't guarantee results.

    If you are building a 3 way loudspeaker, TMW, you can get great performance
    out of this simple old school design and more tolerant to errors.
    Since the woofer is doing a higher frequency job, keep it close to the midrange
    for best synergy. Keep the tweeter next to the midrange, and finally align the
    height of the loudspeaker design so the tweeter is at your ear level height
    at the listening position {standing or sitting down, you choose, etc}.

    If you want to add an extra midrange, MTMW, you can do it. Do a generic MTM
    or follow the 'd'appolito configuration', but no guarantees of satisfaction on either.

    If you use a long ribbon tweeter, then you have issues as the center to center
    spacing on the midranges are too high and you can get worse sound. Ideally you
    want the two midranges close to each other as much as possible and sneak the
    tweeter in the middle, often center offset dome tweeter, maybe with cut flanges
    to make it smaller.

    Or.. TMMW is fine and probably much better overal as you can have more flexibility when
    tweaking the sound using the active crossover as midrange center to center spacing is the
    lowest vs. MTM.

    Two midranges have the potential to offer 1/2 the distortion of the single
    driver at the same SPL level. That's why line array rules. Make a line array of
    16 small 4" midranges and you have 1/16 less distortion of the single driver
    at the same SPL. This allows you to push the line array to higher SPL levels
    and have clean sound still.




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