JRS
Major Contributor
That's a good question and one which I would love a definitive answer to. To start with what I do know is that of course ribbons act as a line source and have terrible vertical dispersion--so for many situations a no-go from the get go. AMT's don't suffer the same problem and horizontal and vertical dispersion are similar to a dome. Both can be horn loaded, though I suspect there is only so much that can be done with the limited vertical dispersion with the ribbons. I haven't seen many designs at all using waveguided AMT's. The physical dimensions and construction would seem to make it more difficult, but I cannot say. I do know that when it comes to PA's there are some really, really good ribbons and AMT's.But what is the directivity of these when placed on a baffle, or is the trick to use a suitable waveguide?
I am just old school enough to say that I am less concerned about directivity than many--there have been many fabulous loudspeakers designed and built over my lifetime that didn't check all of the boxes when it comes to a perfect Harmon score and stellar DI. Frankly, I find the whole idea a bit offputting that calibrating an ideal playback curve from the averaged responses of a heterogeneous population of trained and untrained listeners should somehow become "the reference". I do sound for myself, and my partner. And whether buying or owning a space, a proper listening room is a major priority, and so almost of these considerations are moot--I hand voice it to my own ears, have several targets I use and can select from, and no speaker is going to be put in a spot where reflections will rival the direct sound. If so, I would use room treatment first.
So in my frame of reference, an indestructible, highly sensitive and neutral transducer is what matters most, and getting all the DI transitions perfect less so. But I have no doubt that there aren't approaches that check all the boxes, especially with the AMT drivers that have dome like vert dispersion.