We have Linkwitz to thank for so carefully and fully laying out the theory behind open baffle (dipole) designs. However, once the design theory is understood, the same effect can be had much cheaper using alternative drivers. I use Lowther DX4s on open baffle which is based on the Basszilla design. This was really cheap because I already had the DX4s I added a couple high output woofers on open baffle to get the open baffle bass, which is supurb.