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A Dayton 12" subwoofer suitable for a downfiring cainet

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  • A Dayton 12" subwoofer suitable for a downfiring cainet

    My understanding, the RSS315HF driver is not a good choice for horizontal mounting, something about sagging. Not sure how to obtain this info concerning subwoofers.

    Can the Dayton UM12-12 12" Ultiimax driver be used in a down firing configuration? I really want to use all Dayton drivers, Parts Express is a cool company. I plan on building one of the Trix model for the LRC speakers.

    Thank you

  • #2
    Hi Modmark,

    I'm not pretending I'm the ultimate expert, but I found some calculations online from Bucknell university that describe driver sag.

    The short paper gives a rule of thumb for acceptable driver sag when mounted in a vertical (down/up firing) orientation. It says any driver with 5% or less sag is acceptable for vertical mounting. Note...whether you call it "horizontal mounting" or "vertical mounting" depends on what you're considering as reference. Call it vertical mounting if you're thinking about the axis of the driver as your reference, horizontal mounting if you're considering the orientation of the driver's cone face as reference.

    Anyway... If I did my math correctly, the Dayton RSS315HF 12" subwoofer has just under 3% sag, where the Ultimax 12" sub has just under 2%

    Based on that math, either driver should be OK for down-firing, but the Ultimax (having a lower CMS (mechanical suspension compliance)...meaning it resists motion more) has a slight edge in this department. Less of your Xmax is lost to gravity pulling on the driver with the Ultimax.

    Hope this helps!
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    • #3
      That document pretty much matches what PE lists below.

      I've found that most decent drivers fall under 5% with the ones I have calculated in the past.


      • #4
        Something to consider though is that NO sub (or woofer) works "optimally" downfiring (unless, of course, the cone either has zero mass, OR your sub is working in Zero-G).


        • #5
          Thanks sooo much for the info, I will go with the Ultiimax! My wife wanted to buy a Polk subwoofer at Best buys, she going to be surprised when I fire up this beast in a ported enclosure.