I think the Klipschorn is a fine speaker that sounds good in spite of its warts. It was designed in the 1940's. That's impressive to me, all by itself.
On the other hand, a folded basshorn used to 400Hz is not a good idea. Middle "C" on a piano is 260Hz. Think of that. You have most of the fundamental range of voices going through all that wood in the passageways of a Klipschorn. That's what makes voices sound kind of resonant in a Klipschorn. The panels become a sounding board, making voices sound unnatural.
This and other things have been improved using the π cornerhorn design:
- Woofer is acoustically closer to midrange for better integration
- Midhorn is larger and allows lower crossover
- Midhorn covers the entire vocal range
- Midhorn/tweeter crossover is optimized for better summing
- All horns provide constant directivity of 90°
- Crossover is optimized to maintain constant directivity through crossover regions
- Reverberent field is more uniform because of constant directivity