Ultrasonic Raven Supertweeters?

I saw the response graphs for some of the Raven ribbon tweeters, and I was pretty impressed. Quite flat.

I also noticed (though the graph didn't go this high) that the frequency range for the R-1s and 2s go as high as 46kHz! Should I care about having loudspeakers that soar over an octave past 20kHz? It might be cool to annoy dogs, but does it provide additional imaging or anything?

NB: New high-resolution recordings, such as SACD, can produce frequencies well beyond 20kHz.

Thanks, Won

PS Annyone know the impedence of a Raven without the impedence-adjusting transformer?
The impedence of the Raven without the transformer is fractions of an ohm. The ribbon is part of a one turn secondary. From what I have seen of the R-2 and I have access to quite a few of them, primary resistance is about 3 ohms across the audio spectrum. Frequency response as shown by most sources for these is with a smoothing function, in an absolute sense they are a bit ragged; but still sound quite good.

Hm, interesting. I wonder if this has anything to do with the fact that the R-2 sails up to >40kHz, but the R-3 tops out at a paltry 30kHz (hah).

I'm not familiar with ATC. I noticed that they are used in some DIY kits, but otherwise nothing about them. Who are they, and where can they be found?

Also, how did you set up your amp for direct drive? Was there an improvement in the sound in doing so?

Thanks, Won