The best tweeter design

I've been speaker building for 32 years. The best tweeter that I've ever heard is the old Hill Plasmatronics.
I've had great success with ribbons, but they can be beamy and one that can cross low is expensive.
Horn loads: (you can hear the horn)
Diamond dome:(Accuton) Haven't tried them... I'm always on a budget
Ring Radiator: (old advents) ok
Inverted Dome: (Focal) Fast, Detailed, can sound etched & grainy easily with some electronics, wonderful with others.
Soft Domes: I currently use a Scan Speak with excellent results. Alot of variations with very different outcomes.
Bottom Line, use a technology correctly and you can come up with a very nice sounding speaker.

Weseixas, Blkadr, yes the HEA tweeter *does* look like the old Linaeum, but if you have a closer look they have little in common except that they are both tweeters. The HEA tweeter is sort of like a ribbon tweeter in a horn configuration- That diaphragm you see in the photos is a flexible film, and curved in such a way that it is very efficient. I understand that the tweeter has to be padded down so the other drivers can keep up; its about 107-109db 1 watt.

Unlike a ribbon, its not beamy, and even though its really fast, its not bright. They will be at RMAF...

Dracule ,

I do a agree with you about the big Maggies and find that a modded 1.6/ 1.7 sounds better than the big ribbon ones....

Amfibius :

I was not aware the acapella had plasma tweeters .......

Yea, I was going to try out the Peter Gunn modded 1.7 but change in finances prevents me at this moment.