Arny Krueger wrote:

(3) Use drivers whose acoustical response just naturally rolls-off to
perform the function of crossovers. Easier to do with woofers than tweeters.

This seems like it might be possible. I notice a lot of good woofers
out there as well. Tweeters - tougher of course. Few really seem to be
suited for this.

Idea: what about no internal crossover, but some sort of choke/limiter(maybe
active?) that cuts off the speaker signal? Maybe attached to the tweeter
itself? ie - it just ignores signals below a certain point like how
the subsonic filter on my amp does.

(4) Use a driver that can actually naturally seem to be able to cover the
full audio range. Ironically, the best examples of these often end up having
woofers or tweeters added to them at a future point in their development.
They again often end up with frequency-sensitive networks in their system
design, but again these networks aren't exactly crossovers.

I looked and found a couple of examples of this, but 16Khz was the best
I could find. I was initially looking to see if they made tweeters
larger than 1.25 inches, or cone types and ran across a few 3-4 inch
speakers that were pretty close to full-range, but not quite.