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I Stereo and home theater physics problem for fun

  1. Jun 20, 2016 #1
    Some of us are big time into home theater stuff and recently a question came up that I figured somebody here could solve if they wanted to.

    Basically I'm wanting to know the force exerted on a subwoofer enclosure when at max excursion.

    Some of the known parameters:
    this is for an 18" Ultimax subwoofer.
    It has an xMech of a little over 2" peak to peak, so it can travel 1" in both directions.
    The sum of the moving parts including the cone, spider, voice coil, etc., is about 1.5 pounds.
    We would be feeding it a sine wave of 20 hz.
    weight of the entire sub including magnet, basket, etc., is 44.3 pounds, if that matters
    weight of the wooden enclosure it is going in is 61.25 pounds, if that matters

    So basically when 1.5 pounds of mass is going back and forth 2" and 20 times a second in this situation due to a sinewave signal, while being attached to a stationary basket, magnet, and enclosure weighing another 104.05 pounds, what kind of force is being exerted on the baffle of the enclosure? It's basically like trying to predict the recoil of a rifle. Not sure if it is possible or easy.
  2. jcsd
  3. Jun 20, 2016 #2


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    Gold Member

    I would be tempted to model it as a simple harmonic oscillator, and use the relation between omega, k and m derived from the differential equation for an SHO to solve for k. Then you know the force that a spring exerts on an object. ;)
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