Using a horn super tweeter in OB is a compromise but can still give decent dispersion especially when toed in. Not like a Raal ribbon but that would wreck my price point. Since I only crave top end air and cymbal shimmer I tame my tweets considerable which makes for a good blend with the Betas.

I'll soon cut off the Beta dust caps to make way for phase plugs for increased smoothness.

At 98dbs and a Qts over .5 the 12 inch Beta cones move lots of air which is critical for OB.

I guess the OB concept, as old as it is, is still foreign to most folks. Of course if you don't build a pair your chances of hearing them are quite remote. I'm convinced that their simplicity scares companies away as they don't look profitable. There are a few exceptions and Jamo is one. I may build a clone of Jamo's double woofer 3 way someday.

I've noticed that OBs get lots of love on AC.