We also have a wood horn that I designed specifically for the π cornerhorns, but that can also be used on the matched-directivity two-way models. It is very attractive, so most people mount it externally sitting on a cradle on top of the speaker. Of course, the driver-to-driver spacing must be maintained when doing this, in order to keep the angular coverage right.

The JBL PT-K95MH waveguide might well work with my designs, since it has a 90x50 coverage pattern and uniform directivity. However, I have not tested it, and some crossover changes might be necessary in order to set the null angles outside the pattern, as they should be. That's one of my main design goals, in addition to matching horizontal directivity at crossover, I prefer to match the vertical null angles to the vertical pattern of the HF horn. This makes the most natural sound, limiting sound radiated at large vertical angles outside the nulls. In effect, the nulls serve to punctuate the pattern.