We spend too much time talking about tweeters

" So yeah, if we think we can hear to 20k, and tweeters are crossed over at 3.5k then that’s 16.5k of a 20k range... "
What this says is true if one thinks only in Hz, but music is more commonly measured in octaves.  Music covers ten octaves and 3.5kHz to 20 kHz is less than 2and 1 octaves./2

Excuse the typo in the previous post.  What I meant to say is 3.5 kHz to 20 kHz is less than 2 and 1/2 octaves.

Nice job on the new tweeter thread.  grin.
I cannot imagine ever leaving the sealed ribbon tweeters in my speakers. The degree of incredible resolution and detail with no pain is astounding. They are so much better in every way than the Esotar II tweeters were to my ears, and I'd loved the Esotar until then.
I want it all in a speaker but if the tweeter isn't detailed and listenable then the speaker is out. I tried so hard but B&W diamonds-ouch to my ears over the long listen. I did love my old Martin Logan SL3s for transparency but their high frequencies fell away quicker, and could bite with the wrong amp.

Esotar II ‘s were very nice in my C5’s....WILSON inverted domes kicked butt.  Diamonds just allow so much definition through, even on Alto saxophone it just completes the tone and texture in a way I haven’t heard with other tweeters!

Personally I’m MUCH more interested in how well the midwoofer and tweeter work TOGETHER than in the solo performance of either.

A+++. I heard another speaker designer put it this way. The tweeter illuminates the midrange. They must work correctly together.   A pretty straightforward way to put it, but spot on IMO.