stereohermit

Actually, the vertical polar radiation IS biased upward, for fewer cabinet reflections, less comingling of wavefronts, plus the nodal randomization of that type of lens , to me dissappears into the soundfield, more rea.dily Also in my case the tweeter is open air mount , which works out great.

Actually the 1824m EV mid is in many ways in the same genre as the k-55s. Its freq range is quite close, with mediocre detail and fidelity (like the '55s). It is however a "convex drive". which is not the preffered layout. Makes phase plug design a real *****. Also its an 8 ohm unit, so youll have to inversely proportion your x over values accordingly. I believe sensitivity is about 1 db less....It will work in a pinch, after all, there isnt much around these days in a 1 incher that will want to go down to 400cps...dave

and...heres the university... 9you guys werent kidding, this is hard to upload...)

Here they are....The gold one is the '59 university, the lens with the tapered slot is my "gold standard".

Yes, those do look interesting. Ive run assymetric tweeters for years now and i love em. I tried every compression tweeter on the market, practically, and i ended up with a "transylvania tube" mounted to a JBL 2420 with titanium diaphrams. I have a university tweeter from 1959...looks like a diffraction lens.. i will try to j-peg it to the group soon. Give those a whirl and tell us all how they work out.