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How would an aperiodoc subwoofer measure compared to more conventional design?

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  • How would an aperiodoc subwoofer measure compared to more conventional design?

    I did some googling last night and never could find some answers to a few basic questions.

    Aperiodic loading increases the Q of the driver. Regarding sensitivity and extension, how would a subwoofer with a Qt of say .4 and aperiodocally loaded to .7 (assume minimal "enclosure" volume) compare to the same driver in a sealed box with a Qb of .7?

    The air mass inside the aperiodic enclosure will decease efficiency a small amount so lets assume it's negligible in this example.

    in another example... how would the higher frequencies of a midbass or midrange be affected by a mimimal volume rear mounted aperiodic membrane?
    Thanks,
    Aaron

  • #2
    An aperiodic alignment is simply a high loss sealed enclosure. You model it as a sealed box with Ql set to 3. The result is lower Qtc, which can be of benefit with a high Q driver loaded in a small box, but at the cost of sensitivity. The effect above the region of pure pistonic response is negligible.
    www.billfitzmaurice.com
    www.billfitzmaurice.info/forum

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    • #3
      Originally posted by billfitzmaurice View Post
      An aperiodic alignment is simply a high loss sealed enclosure. You model it as a sealed box with Ql set to 3. The result is lower Qtc, which can be of benefit with a high Q driver loaded in a small box, but at the cost of sensitivity. The effect above the region of pure pistonic response is negligible.
      is the sensitivity loss even across the pass band or is it reflected in bottom end extension or...?

      For my clarification (and for the benefit of those playing along at home).

      1) My Qb and your Qtc is the same thing, right?
      2) Ql can be modeld in WinISD,, correct?
      Thanks,
      Aaron

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      • #4
        It's even across the passband where modeling software is accurate, which is approximately two to three octaves above Fb. Qtc stands for Q Total Closed (box). In WinISD Ql is adjusted in the advanced section of the box tab.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

        Comment


        • #5
          Originally posted by aarond View Post
          I did some googling last night and never could find some answers to a few basic questions.

          Aperiodic loading increases the Q of the driver. Regarding sensitivity and extension, how would a subwoofer with a Qt of say .4 and aperiodocally loaded to .7 (assume minimal "enclosure" volume) compare to the same driver in a sealed box with a Qb of .7?

          The air mass inside the aperiodic enclosure will decease efficiency a small amount so lets assume it's negligible in this example.

          in another example... how would the higher frequencies of a midbass or midrange be affected by a mimimal volume rear mounted aperiodic membrane?
          Actually, it decreases the system Q. But like Bill said, it's just a leaky closed box. Still handy for taming high-Q drivers.
          Francis

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