I have obtained the Dayton RSS390HF-4 15", and require advice on the design.\n\nAfter reading Ray Alden's speaker building book and having browsed through 100's of threads. The recommended ported box size is around 9 cu ft, which is not reasonable by any means. Going ported is completely ruled out. Same with other designs like isobaric. Which leaves me with a sealed design. For this driver with sealed, I understand I might have to compromise on the low end or something else to a certain degree. After much contemplation, the only design that I can do, is sealed. Hence this thread.\n\nSo, I have made three decisions to begin with.\n\nDriver is RSS390HF 15" (I already have it).\nDesign is Sealed box.\nAmp is external - XLS 1500 or XLS 2002 (I have both). I also have a MiniDSP.\n\nNext up is box size. Which is where I require advice.\nReading through numerous threads across different forums, I find the sealed box size for this driver vary widely from 2.5 to 6 cu ft.\n\nSo what is the best sealed box size for this driver and why?