The Onken cabinets can get rather large especially if they are used with 15" or 18" bass drivers. They tend to be wide but shallow. However, the Jensen bass loading (i.e. Onken) can be made using much smaller drivers that are amenable for smaller rooms. Welborne used to sell plans for an Onken bass cabinet for use with the Oris horns that were not too big. I had them for a while while setting up a friends Lowther driven Oris horn. These used a 10" driver so the size was manageable.
That's why I suggested the Stonehenge cabinet and an Altec 604 driver. The cabinet ends up around 18.75" wide, 14.75" deep, and 44" tall. These are not tiny but workable in all but the smallest rooms. These can also be placed close to a wall so you save space. You can go to Iconic's website and see pics.
http://www.iconicspkrs.com/stonehenge.html
That's why I suggested the Stonehenge cabinet and an Altec 604 driver. The cabinet ends up around 18.75" wide, 14.75" deep, and 44" tall. These are not tiny but workable in all but the smallest rooms. These can also be placed close to a wall so you save space. You can go to Iconic's website and see pics.
http://www.iconicspkrs.com/stonehenge.html