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"Slot Loaded" Ultimax 15 woofer.

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  • "Slot Loaded" Ultimax 15 woofer.

    First off, I am not sure that "slot loading" is the correct terminology for the hypothetical design I have going here, but due to some unusual constraints in my room, it would be beneficial for me to utilize an enclosure similar to the attached image. My questions are: How would firing into the slot effect performance? Would it behave, or is it analogous to, a band pass enclosure? How far away from the driver must the "endwall" be before it does not have a significant effect on the performance of the enclosure?
    Thanks
    Mark

  • #2
    It is a 4th order band pass, not slot loaded. You can model it in WinISD. If you do you'll see it's not a very good alignment for that driver, a simple sealed cab works better. I'm curious why you feel you have to make it that way. I'm guessing you might not be aware that the radiation pattern of a sub is omni-directional.
    www.billfitzmaurice.com
    www.billfitzmaurice.info/forum

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    • #3
      According to BassBox Pro this driver with the coils in series will have an f3 of 36 hz in a 79.5 liter sealed box or and f3 of 18 hz in a 315 liter ported (4" dia x 8" long) box, and in either case play LOUD. You could put legs on the bottom and fire the woofer down with 3-4" of clearance and there should be no problem. I can't think of a reason why an enclosure like the one shown would be required.

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      • #4
        Originally posted by mwskopf View Post
        First off, I am not sure that "slot loading" is the correct terminology for the hypothetical design I have going here, but due to some unusual constraints in my room, it would be beneficial for me to utilize an enclosure similar to the attached image. My questions are: How would firing into the slot effect performance? Would it behave, or is it analogous to, a band pass enclosure? How far away from the driver must the "endwall" be before it does not have a significant effect on the performance of the enclosure?
        Thanks
        Mark
        "Slot-loaded" is correct (i.e.commonly-used terminology for that type of layout), though it can be modeled as a 4th order bandpass alignment. I doubt that there will not be enough "loading" though in that layout to appreciably change (i.e. reduce) the low frequency cutoff for that build, and that extra panel increases the complexity of the build and may introduce further problems if it's not properly braced.
        Brian Steele
        www.diysubwoofers.org

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        • #5
          Slot loaded is when the driver is mounted on the rear of the baffle, firing into a literal slot. There are two reasons for doing this. One is that the air mass of the chamber in front of the cone lowers system resonance, the other is that the diffraction provided by the slot widens midrange dispersion. You don't see this done much, not because it doesn't work, but because the average consumer doesn't understand how it works and thinks, wrongly, that blocking part of the cone will have an adverse effect. Trace Eliot bass cabs used them for a while, as did TOA as pictured below, both failed to gain marketplace acceptance.



          The OP's configuration is usually referred to as a manifold.
          www.billfitzmaurice.com
          www.billfitzmaurice.info/forum

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          • #6
            All,
            Thank you all for the responses! It does not sound like the arrangement I show would be very advisable. My situation in the room is kind of hard to explain (i'll attach a simplified sketchup image to try to clarify) . It has to do with the closet where I want to place the sub enclosure. The closet is kind of offset from the corner of the room and I would kind of like to save some room in the closet for other gear/house stuff. That is ok though, I was posting the question for curiosity sake as well as performance sake. I can sacrifice some closet space to do a more "conventional" arrangement.
            Thanks again for the replies!
            Mark

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            • #7
              There have been sub designs where the box was located downstairs under the floor, and a duct went up to a grill in the floor to save space upstairs!

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              • #8
                This brings up Murphy's Law of Sub Placement: Wherever it's most convenient or most aesthetically pleasing to place a sub, or where you wife will allow you to place it, is guaranteed to give the worst possible result.
                www.billfitzmaurice.com
                www.billfitzmaurice.info/forum

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                • #9
                  Well, Murphy may indeed strike, hopeully not, but this is where she's going. I plan to use an amp with DSP so perhaps that prove useful when the time comes. I may run one more sub wire to the front of the room before I finish putting the drywall up. I guess there is the bluetooth connection option as I have plenty of outlets around, but I don't have any experience with going that route.
                  Thanks

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                  • #10
                    Are there any kind of parameters for slot loaded performance or is it just trial and error?

                    I've always wanted to partially slot load a mid/bass with some wide dispersion horn setup.......maybe even with a coaxial?

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                    • #11
                      You can model the slot effect on lows as a 4th order bandpass, The highs are trickier, ideally you'd want the slot width 1 wavelength at the upper end of the intended pass band. I don't think it would work well with a coax. The slot increases horizontal dispersion but it also is a low pass filter, so you can overdo it. How the slot affects the highs can be seen with this applet:http://www.acoustics.salford.ac.uk/f...tionslider.swf
                      You need flash player to use it.
                      Last edited by billfitzmaurice; 06-21-2018, 04:02 PM.
                      www.billfitzmaurice.com
                      www.billfitzmaurice.info/forum

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                      • #12
                        Originally posted by billfitzmaurice View Post
                        You can model the slot effect on lows as a 4th order bandpass, The highs are trickier, ideally you'd want the slot width 1 wavelength at the upper end of the intended pass band. I don't think it would work well with a coax. The slot increases horizontal dispersion but it also is a low pass filter, so you can overdo it. How the slot affects the highs can be seen with this applet:http://www.acoustics.salford.ac.uk/f...tionslider.swf
                        You need flash player to use it.
                        Appreciate it bill.....I downloaded the latest flash player but still can’t get that to work....too bad, looked interesting.

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                        • #13
                          It works with Adobe Flash player, which is pretty much standard issue with most PCs. Mine is version 30.0.0.113, freeware if you don't have it.
                          www.billfitzmaurice.com
                          www.billfitzmaurice.info/forum

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