We spend too much time talking about tweeters

     I believe there was a Tweeter in Chief in the not so distant past. 
    So, they must have been important at some point, right?

Tim

Yes Tim, and there's nothing worse than having to listen to a bad tweeter, right?

Look at this another way, how often do we nit pick speakers apart because of the mid driver? The technology there, etc?

I’m with @audiokinesis on this one. Listen to a small jazz combo from up close (well ... wait until after the apocalypse). Pay attention to the cymbals and then go back to your hi-fi system.

99% of the tweeters out there (many of them in "aspirational" speaker designs) make a cymbal sound like uncorrelated noise.

It’s not only about triangles and cymbals however. These upper frequencies build the harmonic structure in other instruments, by (a) being low in distortion and (b) integrating well with the midrange. When you hear a gorgeous cello, it’s because of the upper frequencies being done right.

... Thom @ Galibier Design