Ring radiator tweeters - the future?

"I'm not sure it requires any math?"

Oh contray..how wrong you are.

Construction and Measurement of a Simple Test Transmission Line.

A Mathematical Model for an Expanding Fiber Damped Transmission Line

The Calculation Algorithm

Derivation and Correlation of the Viscous Damping Coefficient

Advanced Transmission Line Modeling Techniques

Does it look like you're just throwing a driver in a box? I agree some SDs aren't bass or dynamic monsters. There are some that do large scale very well..most aren't commercially manufactured though. Also the consumer must decide what kind of bass they want to live with. Do they want 50hz bass hump kinda of bass or real honest bass with low distortion that adds as little as possible to the original recording?

Cheers

Thanks for the links, and do I need to say transmission lines are not exclusive to SD designs?

Yes you're correct they aren't. Although the links supplied are exclusive to SD designs not multi ways. To give you an idea..this is comparing apples to oranges. I'll use the Paradigm 100v2 and v3 speakers because they are so widely sold. I've also spent enough time with them to judge them well. The Paradigm 100v3 is a five driver three way speaker. They will play much louder than my FTAs.One of the things they can't do is compete with the FTAs in bass/weight extention.

That's right..the single 8 inch driver in a MLTL cabinet makes this 5 driver speaker sound like a welterweight in the bass department that put on too many pounds. In other words the 100v3 sounds slow, sluggish and light in the bass by comparison...believe it or not.

Output is relative, the Paradigms flatter response will work against its perceived bass output. Fact is the Paradigms use 8" woofers so why would I expect them to go any lower than an 8" in a t-line.

As you mentioned they just go louder. The mass production of the Paradigm speaker will also open the door for minor bass misalignments and the 100's are tough to drive. My least favorite speaker in the reference line since its inception by Paradigm.

Eldartford sez:

My idea is to exploit the extended range capability by using a FR to cover the range from 100 Hz to 8KHz or so, with a SW below and a tweeter above

You'll enjoy yourself immensely on that one! I expect you'll find that the tricky part is marrying the woof to the FR. IF you can hi-pass the FR & leave it alone thereafter, it's a bonus.
You're lucky in that you're already used to having (seeing) obtrusive panels in yr room... Cheers