Was QWR that I was most unsure about, but no, know nothing about quarter wavelength resonators, while familiar with the terms transmission line and tapped horn haven't dived into those much let alone tried to design/build one, altho some of the transmission line designs might be interesting. Helmholtz resonators you're talking ported subs? Or an absorber? If you have the building/design skills for the more complicated designs go for it....