For the 4-Pi's I'm going to start shortly, I ended up getting
Selenium 25-25 horns. Similar to the ones you recommend in dimensions, etc. While trying to pick a horn, I noticed that
similar sized horns were rated for pretty dis-similar cut-off, and
at the same time, some rather smaller horns were rated for what
seemed like pretty low cut-off. Aren't those specs pretty much
dictated by physical dimentions related to the size of the sound
waves? Any explanation for the spec games?

BTW, the Selenium horns are nicely finished, heavy dead aluminum,
with a nice wide rim (as opposed to some complaints I've seen about
one or the other 1" horn you specify). I'll post more once I get
things hooked up.

thx, Chris