Plans for smallish horn speakers that can go into the corners

Hey guys,

I don't know if something like this was already covered by Ingvar (or anybody), but if there are building  plans for smallish horn speakers that can go into the corners, please point me in that direction. If there are any other ideas, except for horns, it is good, but it must be able to convert my brother from his B&W 801 Matrix speakers!

Thanks!  ;D