Other benefits as well?
Yes, in most cases, the crossover work is easier if the tweeter acoustic center is horizontally recessed. This is my experience. There are essentially two elements of crossover design goals - phase and amplitude. If a guy could mechanically/physically adjust the phase, the only item remaining is the amplitude - much easier!!
1.8khz seems low, but if the crossover is steep, this can work. I haven't don't this, but it has been done before. Geoffrey Dillon used a steep slope on the OW1 at 1.8khz many years ago with very good success.
I believe the speaker was called the Metaphor.
The tweeter does become more directive because of the waveguide. I wish I had a chance to hear Dave's 1801b to determine if my approach produced the same luxurious sound.
Well, I have a few comments in no specific order.
1. Soft cones are more difficult for the crossover designer
. They require some more "art" and interpretation. A nice stiff cone has a very simple (but nasty) resonance to accomodate. Hence, if you managed to control the resonance (fairly easy), and the amplitude is correct to the ear, the sound is likely darn good.
2. Accomodating the tweeter waveguide via measurements might be more difficult and your response curve may NOT look typical and pretty on axis. You may have done this, but I suggest many off axis and in room responses to determine what is actually happening. Further, if it sounds correct, then it probably is. I had some really whacky stuff happening when I puttered with the Accuton C95 driver. Eventually I got it figured out, but it took considerable time.
