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.
So an appropriate tweeter with narrowed vertical dispersion and wide horizontal dispersion was needed. A small faceplate was also required. After a search of a very short list, the Dayton AMT2-4 was selected.
The woofer had only to cover up to about 500hz, but I wanted very low distortion there, and not too sensitive to match the BMR's which must be run in series. This was not as easy as I'd hoped, many drivers have very low distortion performance in the bass, but not so much in the midrange, while other were great in the midrange while 3rd and 5th harmonic really increased in the bass. I thought a great compromise would be the Usher 8945A or 8948A, and I love the pulpy cone look of the 8945A. BUT just about the same time the Dayton Esoteric woofers came back so I threw both in the basket for testing. In the end the Dayton ES180TiA was a perfect fit, not too sensitive, fantastic distortion measurement through the whole design's passband, and being a Dayton will go on sale much more often then the Ushers. No it doesn't have the pulpy cone, but the carbon fiber is pretty dang cool too.
So now that all that's out of the way: here is an *almost* final mockup drawing
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 Symmetro:
Now the aim here was not supposed to be the "best ever speaker". It's a proof of concept. A solution to a problem that has bugged me. But I like what I see so far. Will it do everything I hope when I get it in-room? We'll see
So an appropriate tweeter with narrowed vertical dispersion and wide horizontal dispersion was needed. A small faceplate was also required. After a search of a very short list, the Dayton AMT2-4 was selected.
The woofer had only to cover up to about 500hz, but I wanted very low distortion there, and not too sensitive to match the BMR's which must be run in series. This was not as easy as I'd hoped, many drivers have very low distortion performance in the bass, but not so much in the midrange, while other were great in the midrange while 3rd and 5th harmonic really increased in the bass. I thought a great compromise would be the Usher 8945A or 8948A, and I love the pulpy cone look of the 8945A. BUT just about the same time the Dayton Esoteric woofers came back so I threw both in the basket for testing. In the end the Dayton ES180TiA was a perfect fit, not too sensitive, fantastic distortion measurement through the whole design's passband, and being a Dayton will go on sale much more often then the Ushers. No it doesn't have the pulpy cone, but the carbon fiber is pretty dang cool too.
So now that all that's out of the way: here is an *almost* final mockup drawing
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 Symmetro:
Now the aim here was not supposed to be the "best ever speaker". It's a proof of concept. A solution to a problem that has bugged me. But I like what I see so far. Will it do everything I hope when I get it in-room? We'll see
Comment