Frugel horn. Would somebody care to explain the design?

[walpurgis]

The Frugel Horn is a speaker that keeps cropping up here, but it's also one that has a few questions around it's design and implementation.

Pictures of these I've seen here show it situated and used as a free standing speaker, yet I understand it is a corner design. In other words, I assume it should be positioned tight into a corner for wall reinforcement from the corner angles, which would form the horn flare/termination. This suggests to me that nobody is using them correctly.

Also, the cabinet starts off as what appears to be a quarter wave type horn, only to feed the rear exit through a small vent more suited to a reflex design, which I suspect is what it is in reality (Castle used a similar design). It certainly is not a true quarter wave horn.

Is anybody able to shed some light?