So is this new Folded Motion transducers replacing the ATF transducers and that's why they are discontinuing the other models? Is this "new" technology an advancement of the ATF?
From all appearances, the Folded Motion transducer is the same technology as the
Heil Air Motion Transformer, which has been around at least since the late 70s/early 80s. ML even quotes the same "8 times surface area" of a conventional cone/dome speaker associated with the AMT. I still own some
ESS AMT-1C speakers from that period. Heils are very efficient, but some say that they're too bright. I imagine that ML has improved on the design and probably addressed that issue.
I'm less enamored of the Folded Motion Cascading Bass Port - it looks an awful lot like the snake oil that Bose has been pushing for years. I am not a speaker designer however, so appearances may be deceiving.
Heil actually had an AMT version of a bass driver - it was used on the ESS "Transar" line of speakers, but required a large physical space to implement, and frankly wasn't that impressive in terms of delivering punch. It had a transducer at the bottom that pushed four rods up through a stack of emitter elements, with each emitter having a forward and backward output, looking somewhat like two clamshells stacked in an "S" orientation, facing opposite directions with a membrane between the two cups.
edit: I found a picture of a Transar at Audio Asylum. For scale, it's about five feet (1.5 meters) tall:
The thing at the top-center is the conventional mid/high-range AMT. The things under that are the stacked clamshell emitters for the bass driver. The box at the bottom is the driver that pushes the rods for the bass driver(s).
For some reason, the image won't display in-line despite "IMG" tags, oh well.