Thanks, I found it. The Jubillee reads very interesting, I don't suppose your friend there gave you any cutaway drawings OTOH, I wonder about the claim that it can go to 1000 Hz. One of the (lesser) problems with the (measured) response of the K-horns (and LaScalla/Belle) was the interference between the two sides of the horn mouth. PWK discussed this in a Dope From Hope around 1961. My memory (don't have the issue in front of me) was that it was around 250 Hz. Paul said something about tightening driver specs, again, I am relying on memory of a document I haven't seen recently (I just moved and still setting up my library). It would seem that this problem would be intrinsic to any two-path symmetrical horn.