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combing near and far field measurements?

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  • combing near and far field measurements?

    I'm measuring a little desktop speaker, and needed to combine measurements at
    1 meter with close miked woofer and port measurements. My question concerns
    what freq to splice them and what level.

    Here is the set of measurements combined where the curves intersect.
    Click image for larger version

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    At first I thought that was correct, but the overall FR then shows almost a 10dB
    drop from 40Hz to 4K Hz - which I don't think is correct, since the speaker
    sounds pretty balanced low to high. Any tips?

    I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
    "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

    High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
    SB13/Vifa BC25SC06 MTM DCR Galeons-SB13-MTM
    My Voxel min sub Yet-another-Voxel-build

    Tangband W6-sub

  • #2
    Re: combing near and far field measurements?

    my guess is where they intersect.
    " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

    Quote Originally Posted by hongrn. Oct 2014
    Do you realize that being an American is like winning the biggest jackpot ever??

    http://www.midwestaudioclub.com/spot...owell-simpson/
    http://s413.photobucket.com/albums/pp216/arlis/

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    • #3
      Re: combing near and far field measurements?

      I use ARTA to measure. I never cal'd my (mic's) SPL using voltage; have just measured (nominally) known flat drivers (esp. tweeters) and set my mic sensitivity (in ARTA) so I no longer had to (arbitrarily) add +110dB to all my measurements.

      Anyhoo; I (almost always) set my gate window to 3.333ms (I COULD go longer sometimes, but I'm trying to target consistancy here), which ARTA says means my measurements are accurate down to 300Hz. When I measure nearfield (like, 1/4"), I change my gate to 33.33ms; so THAT should give me a good curve down to 30Hz. THEN, I can just subtract dB (from the nearfield) until my 2 measurements align at 300Hz. Not sure how I'd add port output to that? Maybe port output is so low (20-60?) that it's included in the close mic'd measurement? Seems like it COULD be, down at those Fb freqs?

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      • #4
        Re: combing near and far field measurements?

        Thanks guys!

        I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
        "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

        High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
        SB13/Vifa BC25SC06 MTM DCR Galeons-SB13-MTM
        My Voxel min sub Yet-another-Voxel-build

        Tangband W6-sub

        Comment

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