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Proposal: Jupiter X4 Omnidirectional Speaker

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  • Proposal: Jupiter X4 Omnidirectional Speaker

    So I am thinking about building an omnidirectional build next, since I've done a solid conventional two-way design. Here is what I am thinking, please give me input.

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    Two tube chambers.

    The bottom one contains an upward firing HiVi M8N woofer, 8" diameter, likely made using a concrete forming tube and clay molded around that. The top and bottom plate will be some nice wood cut with a circle jig, both joined to each over via 3 or 4 dowels on the outside of the tube. Bottom chamber is ported, 2.5" flared tuned to about 40 hz for nice full-range extensions.

    The top one contains a downward firing Vifa TC7FD 2" full-range for the top octaves, small sealed.

    In the middle of the two is a wood plate they are firing against, not sure how I should shape the top of how much distance I should leave. Right now there is 2" between that plate and the M8N, and 1" between it and the TC7. I'm interested in seeing the response of both with various spacing lengths.

    Thoughts?
    Audio: Media PC -> Sabre ESS 9023 DAC -> Behringer EP2500 -> (insert speakers of the moment)
    Sites: Jupiter Audioworks - Flicker Stream - Proud Member of Midwest Audio Club

  • #2
    Re: Proposal: Jupiter X4 Omnidirectional Speaker

    You're going to have big issues with the off axis performance of the TC7FD unless you get some kind of 360 degree deflector between it and the M8N.
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    • #3
      Re: Proposal: Jupiter X4 Omnidirectional Speaker

      Maybe like this?
      Click image for larger version

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      Kenny

      http://www.diy-ny.com/
      DIY NY/NJ 2014 https://www.youtube.com/watch?v=FGwA...ature=youtu.be
      Man does not live by measurements alone, a little music helps.

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      • #4
        Re: Proposal: Jupiter X4 Omnidirectional Speaker

        Try this:
        Attached Files

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        • #5
          Re: Proposal: Jupiter X4 Omnidirectional Speaker

          Pete, I had a feeling, which is why I was going to measure before I commit to any one design for the TC7 half up top.

          Kenny, djg, I think you two are getting towards the same thing. Making a surface out of rigid polymer clay shaped as needed is likely what I will try first. I also think that making sure the space between that shape and the cone needs to be tight, since we are talking about 1" waves or less above 12 khz or so.
          Audio: Media PC -> Sabre ESS 9023 DAC -> Behringer EP2500 -> (insert speakers of the moment)
          Sites: Jupiter Audioworks - Flicker Stream - Proud Member of Midwest Audio Club

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          • #6
            Re: Proposal: Jupiter X4 Omnidirectional Speaker

            Oh and if you can think of a better option than the TC7 loaded into some kind of reflector let me know. I only picked that way because I tossed my hands into the air with the exclamation "Well you got me!" heh
            Audio: Media PC -> Sabre ESS 9023 DAC -> Behringer EP2500 -> (insert speakers of the moment)
            Sites: Jupiter Audioworks - Flicker Stream - Proud Member of Midwest Audio Club

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            • #7
              Re: Proposal: Jupiter X4 Omnidirectional Speaker

              The Visaton omnidirectional speakers might be worth a browse.

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              • #8
                Re: Proposal: Jupiter X4 Omnidirectional Speaker

                Thanks Andy those are right in line with how I'm thinking about these. Though in all honesty the idea started simply as: What about a two-way version of the Top Hats?
                Audio: Media PC -> Sabre ESS 9023 DAC -> Behringer EP2500 -> (insert speakers of the moment)
                Sites: Jupiter Audioworks - Flicker Stream - Proud Member of Midwest Audio Club

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                • #9
                  Re: Proposal: Jupiter X4 Omnidirectional Speaker

                  Looking at these and thinking,

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                  Does it matter what size driver I use for the top-end? I mean, excepting it needs to have treble response, obviously. I'm starting to think about a compression driver too with a horn deflected by another horn of the same profile.
                  Audio: Media PC -> Sabre ESS 9023 DAC -> Behringer EP2500 -> (insert speakers of the moment)
                  Sites: Jupiter Audioworks - Flicker Stream - Proud Member of Midwest Audio Club

                  Comment


                  • #10
                    Re: Proposal: Jupiter X4 Omnidirectional Speaker

                    So as I played around with some ideas in my head I came up with this for an omnidirectional tweeter:

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                    That is two 3" round discs, 3mm thick, with a 1 1/8" diameter cut for the OX20, placed 1/4" apart with three "spacers" which glued it all together. The concept is that with the two OX20's firing into each other, just millimeters apart, they create a point source at that location. For all audio experts/professionals, How far off am I in this thinking?

                    Mocked it up and measured it. Pretty impressive response for such a flawed design. The measurement (which I forgot to save) showed two dips: a shallow one at 4.5 khz and a larger one with a matching 2nd order rise at 9 khz. The whole response had a gentle roll-off starting at 12 khz. It was ragged enough though I was ready to just give up entirely until I got the thought: lets rotate it and measure again. This gave me a totally different response...

                    The culprit, as I am thinking right now, is the spacers in effect making three little waveguide/horns. This wasn't my intent in any fashion, the next design attempt will remove those spaces in favor of something outside the interior that will hold the plates together. Maybe like so:

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                    Audio: Media PC -> Sabre ESS 9023 DAC -> Behringer EP2500 -> (insert speakers of the moment)
                    Sites: Jupiter Audioworks - Flicker Stream - Proud Member of Midwest Audio Club

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                    • #11
                      Re: Proposal: Jupiter X4 Omnidirectional Speaker

                      You could try spacers used for PC boards. The metal kind.
                      Kenny
                      Kenny

                      http://www.diy-ny.com/
                      DIY NY/NJ 2014 https://www.youtube.com/watch?v=FGwA...ature=youtu.be
                      Man does not live by measurements alone, a little music helps.

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                      • #12
                        Re: Proposal: Jupiter X4 Omnidirectional Speaker

                        Funny, I've had one of those things sitting on the back seat of my car for a while now.

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                        • #13
                          Re: Proposal: Jupiter X4 Omnidirectional Speaker

                          Originally posted by Chris Roemer View Post
                          Funny, I've had one of those things sitting on the back seat of my car for a while now.
                          A metal spacer/standoff?
                          Audio: Media PC -> Sabre ESS 9023 DAC -> Behringer EP2500 -> (insert speakers of the moment)
                          Sites: Jupiter Audioworks - Flicker Stream - Proud Member of Midwest Audio Club

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                          • #14
                            Re: Proposal: Jupiter X4 Omnidirectional Speaker

                            No . . . that whole flying saucer thingy.

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                            • #15
                              Re: Proposal: Jupiter X4 Omnidirectional Speaker

                              The distance in inches (X) from the tweeter center to the edge of the discs is what? 13560/X = ?

                              I bet that is your 9kHz issue.

                              Furthermore- This in effect is not Omni due to the limited vertical directivity this 'platter' approach will yield. It's more of a 360* lateral waveguide.

                              Possible improvements:
                              -Larger platter to lower the frequency blemish to below xover range.
                              -rounded edges on the platters to ease sound entrance into air for less diffraction.

                              Let me know how that goes...
                              Wolf
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