Open back front horns

Some time back I came across a site for a big straight horn subwoofer (I think the guy was in northern Europe somewhere) but I can't find it to save my soul. I remember that he talked about having pretty good results without a back chamber (i.e. open back) which I find interesting. Does anyone have the link? Also I would be interested in any other information that I could get on open back front horns.

I'm sure someone else has the link to the straight horn you refer to. I believe the writeup on those mentioned designing around some donated drivers and that superior results might be had by researching drivers more suited to horn bass. A commercial product under the Bassmaxx brand uses this design and a search on their name showed promise of more info.
For bass an open back front horn is just an RLH, Rear Loaded Horn, isn't it? If you were talking about mid or high frequencies I guess it could be something different like an OB with some horn loading on the front side.

Actually more like an infinite baffle front loaded into a horn. The actual driver is in another room.

As I understand it the rear chamber is used to load the driver especially below horn cutoff. If the driver is relatively high Qts then it seems that the rear chamber required would get rather large. At some point might it not approach an infinite volume?