I have a JBL 4648A box that I just took the drivers out of (needed them for another project) and instead of ditching the box, I want to make a sub. The 2 holes are for 15" JBL pro drivers and the whole thing has an interior volume of 8ft^3. I would like to play down to around 14Hz. Any suggestions on two drivers for this endeavor? Or one driver and I can fill in the other hole. I was thinking about sound splinter drivers but I'm not sure that would work best for this application. Any thoughts?