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Thought I'd share a project Derek (deschu) and myself are working on. This started with my experience that despite the technical shortcomings of the MTM, I often really like their sound, better than an identical TM at times. I'm not the only one and I think the assumption is that there is reduced sound power - especially vertically - around the crossover, which is typically a region sensitive to the ears. I also know that I hate low ceilings for good sound. After the wall behind the speaker, the ceiling seems - to me - the next worst offender. So I started thinking about how I could control vertical dispersion, while maintaining - or even increasing - horizontal dispersion compared to a typical speaker. I'd already had an idea for the layout, either MMTMM or WMTMW, with the proper driver spacing vs crossover to constrain the vertical dispersion. But the mids must be tiny to get close enough so they're vertical dispersion is constrained, but not so much that it was very different from the rest of the speaker response. When I started working with the Tectonic Elements 46mm BMR in a soundbar project and an AMT in a dipole, the final concept clicked.
For the conceptual modeling you will notice that the vertical dispersion is quite constrained in the window where ceiling/floor bounce matter. Constrained and even. The mid/tweet crossover region- expected to be the worst - is constrained but also bigger than say a typical MTM. In addition above and below that is also constrained, so that what does get reflected will at least be a smoother response than say, a lot midrange/bass energy bouncing up or down, then suddenly a laser beam in the mid/treble area, and then back to treble spraying everywhere. Here is the polar response from 500hz-4500hz of a typical 2-way TM:
And a typical 3-way TMW:
And this is Symmetro:
For the conceptual modeling you will notice that the vertical dispersion is quite constrained in the window where ceiling/floor bounce matter. Constrained and even. The mid/tweet crossover region- expected to be the worst - is constrained but also bigger than say a typical MTM. In addition above and below that is also constrained, so that what does get reflected will at least be a smoother response than say, a lot midrange/bass energy bouncing up or down, then suddenly a laser beam in the mid/treble area, and then back to treble spraying everywhere. Here is the polar response from 500hz-4500hz of a typical 2-way TM:
And a typical 3-way TMW:
And this is Symmetro:
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