We spend too much time talking about tweeters

Something noticed about my AMT's is that 'played ' without a bass speaker of any size sounds like strangling a small animal...and they go down to +/- 500hz.....
Matching the 'speed' of an AMT (or a ribbon, small planars, and the like) almost requires crossing over to a smaller woofer properly.  Hand over the sub-150hz and below to a decent sized sub to 'move' substantial amounts of air about....
I've found that adding a smaller (and lighter) Walsh to my larger ones makes a substantial difference to their response and to the general perceived 'air' from them.  'Uncoupling' the 'top' fq radiator and using a smaller voice coil (contrary to the design of the F's and A's of the past) may be heresy but it does seem to work well.
(I'm not using a typical 'enclosure' with the larger Walsh unlike Ohms', new or old.  Just a sealed tube; think 'acoustic suspension', to damp excursion...).
The Tweet Matters, basically.  But what's 'below' completes the 'image'. ;)

Nobody has quoted the immortal lyrics of Meghan Trainor:
I’m all ‘bout that bass, ‘bout that bass, no treble...
i can shake it like I’m supposed to, cause I got the boom boom that all the boys chase...

What is wrong with your people?!

I sort of prefer omnidirectional heights. Not much choice there though, mainly German (MBLs, German Physiks DDD, and Elac super tweeter).

Matching the 'speed' of an AMT (or a ribbon, small planars, and the like) almost requires crossing over to a smaller woofer properly.

I have Mark & Daniels first iteration of their Ruby loudspeakers and this is basically what they did. Their AMT tweeter covers 900Hz on up and their 5" woofer handles the rest down to 45Hz. Terribly inefficient little beasts (82.5dB/2.83V/1m) but they sound fantastic driven properly.

     I generally try to avoid talking about 2 things too much: tweeters and, at my wife's often frantic request when we're with others, how bald eagles taste like chicken.
     Speaking as we sometimes do, however, about excellent tweeters and treble transducers, professional audio reviewer Chris Martens once stated in a fairly recent review: 

"Magnepan’s ribbon tweeter features an ultra-thin aluminium foil ribbon approximately ¼-inch wide and five feet long. Many audiophiles regard this tweeter as one of the finest high-frequency transducers in the world and I count myself in that group; it offers smooth and beautifully extended highs and astonishingly quick and nuanced handling of treble transients and textures.

Magnepan offers few details on the crossover of the 3.7i, but on the basis of talks with Winey and Diller I gather a time/phase coherent network is used."

     To anyone who has listened to the Magnepan 3.7i or 20.7 speakers in person, they certainly know these review statements are rather obviously true.  But even though both of these speakers devote 70% of their very large planar-magnetic dipole panel's real estate to bass output below 350 Hz, it's also quite obviously true that their quasi-ribbon bass dipole transducers are able to only approximate the very high quality level in bass performance that their true-ribbon tweeter dipole transducer manages to display in treble performance. These 2 larger Magnepan models also lack the extraordinary extension, power and impact as well as the same extraordinarily realistic dynamics in bass performance that they possess in the treble frequencies.  

     It's not only evident to me that these very good models lack high quality bass extension and powerful bass dynamics, Magnepan itself  acknowledged this reality quite clearly a few years ago by coming out with their 1st new top model speaker design in decades, the model 30.7, that consists of an included pair of separate bass modules in an attempt to compensate.

     I suggest the lesson to be learned is that it's likely best if any hi-end speaker company ensures its top speaker model are high quality performers, that they're well balanced and reproduce the entire audible audio spectrum with as high a degree of capability as they can muster, ideally with bass that is accurately and naturally felt as well as heard.

Tim