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  • MTM Overnight Sensation, Slot Vented

    Just throwing up a .jpg of the finished drawerings. 16" H, 7.75" D, 6.875" W with a 6" wide baffle. Slot vent is 0.75" x 5.25" x 10". This design shrinks down the net volume to 7.7L; penalty is a slightly higher F3 of 57Hz. Curvy like the MTs I built. The sides will be three layers of 3mm Birch ply like the MTs as well. I haven't decided yet, but I may try to put a slanted roof on these. Slanted and curved may make a nice combo, and be easy to handle on this small'ish enclosure. (and get the net volume back up a little bit)



    Will post up the slanted version in a few days.
    ~Mark

    Stuff I've builded http://techtalk.parts-express.com/co...lies/smile.png

  • #2
    Re: MTM Overnight Sensation, Slot Vented

    That's some amazing CAD work!

    Looks like a good plan. But why not make the cabinet a bit deeper to get some more volume?
    Isn't it about time we started answering rhetorical questions?

    Paul Carmody's DIY Audio Projects
    Twitter: @undefinition1

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    • #3
      Re: MTM Overnight Sensation, Slot Vented

      how did you draw those? they are thuper thexxy.
      " 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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      • #4
        Re: MTM Overnight Sensation, Slot Vented

        Due to the curved sides, it looks like the port is going to have an expanding profile (and then a slight contraction) along the bottom of the box. If that is the case, I suspect it won't respond quite the same as a linear straight port. That's not necessarily a bad thing but you would have to model it with Hornresp or MJK's mathcad worksheets or some similar software to make sure it's going to behave the way you want it to. That port shape would definitely change the tuning frequency and resonant behavior.
        Don't even try
        to sort out the lies
        it's worse to try to understand.

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        • #5
          Re: MTM Overnight Sensation, Slot Vented

          Damn. That is some quality cad work.

          What program did you do that in?

          Nice design as well.
          My projects
          https://picasaweb.google.com/112307725038877176664

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          • #6
            Re: MTM Overnight Sensation, Slot Vented

            Originally posted by diy speaker guy View Post
            Due to the curved sides, it looks like the port is going to have an expanding profile (and then a slight contraction) along the bottom of the box. If that is the case, I suspect it won't respond quite the same as a linear straight port. That's not necessarily a bad thing but you would have to model it with Hornresp or MJK's mathcad worksheets or some similar software to make sure it's going to behave the way you want it to. That port shape would definitely change the tuning frequency and resonant behavior.
            Yup. It's not without it's challenges. Still need to fiddle with the flairs as well, which is where I was considering taking up some of the error. Messing with the stuffing density may be enough to compensate if I lean towards the smaller dimension to calculate my lengths. Yes?

            Originally posted by Paul Carmody View Post
            But why not make the cabinet a bit deeper to get some more volume?
            More or less aesthetics; any computers that these would be flanking are flat panels, and they average a depth off the wall of around 7". While I want nothing more than killer tunes, I don't want the bases to be encroaching on my happy desk bubble. That leaves me with height, which is less of a concern but the height to width ratio to the eye starts to get wonky.

            Long story short, I'm still fiddling. I've been drawing everything so far in Microsoft Visio. Sketch-Up or Solidworks would be best of course, but my 3D imagination isn't broke enough that I can't just visualize and attack.
            ~Mark

            Stuff I've builded http://techtalk.parts-express.com/co...lies/smile.png

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            • #7
              Re: MTM Overnight Sensation, Slot Vented, Reworked

              I reworked the design a bit today based on issues as pointed out by Paul C. and DIY Speaker Guy..

              The slot vent was the biggest change; instead of dealing with weird vent geometries and possible tuning snaffoos, I brought the vent forward in the enclosure to a point where the 5.25" width intercepted the enclosure sides. This worked out well for crossover and speaker terminal placement as well, keeping them out of the way.

              The volume was increased to 8.2L, or 500 in^3, so the tuning bumped back down a bit towards Paul's original design. New Fb and F3 are 59 and 55 respectively. (perfectly flat enclosure response requires 550 in^3, so I ain't too far off) The overall cab dimensions aren't hurting me too bad. When all is said and done, these will probably be used in the bedroom or as portables coupled to the gainclone.

              For the sake of my sanity, I think I'm officially done with the design phase, less throwing a few dimensions around for cutting. ... *yawn* Need Coffee. :D

              ~Mark

              Stuff I've builded http://techtalk.parts-express.com/co...lies/smile.png

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              • #8
                Re: MTM Overnight Sensation, Slot Vented

                That solution definitely makes the cross sectional area a lot more stable through the bottom of the box but it appears that you had to make the port shorter to do that. Maybe not.

                Anyway, I was imagining a different solution that would maintain a constant cross sectional area all the way through the port. Just block off the flared sides with a couple of little pieces of scrap. Something like this.



                It's just an idea. Just remember to keep the port cross sectional area (and flare rate - none if possible) and also the port length as close as possible to the original design and it should work out great.
                Don't even try
                to sort out the lies
                it's worse to try to understand.

                Comment


                • #9
                  Re: MTM Overnight Sensation, Slot Vented

                  That's pretty much the plan; the reason I went with the middle of the box was due again to aesthetics, and to keep the cross sectional area of the vent up. Side benefits included free bracing for the lower half. The vent did shorten, but it was mainly due to the increase in enclosure volume. As you drew it, the vent was going to terminate in a corner (yuck).
                  ~Mark

                  Stuff I've builded http://techtalk.parts-express.com/co...lies/smile.png

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