If you look at the 8" full range drivers he sells, they do have a lot in common. Typically they have a fs between 50 and 60 Hz, a Qts between 0.20 and 0.35, and a Mms between 10 and 15 gm (so the Vas values are also close). This includes the Lowthers and the Fostex drivers. If you put any one of these drivers in a ported enclosure tuned to say 55 Hz, the final performance of the drivers will be close. The enclosure only reinforces the bass below 100 Hz. The amount of bass produced will be a function of the Qts, low Qts will have weaker bass output. His enclosure will work under the right conditions but they are probably (maybe I could claim definitely) not optimum.

Martin

• Quarter Wavelength Loudspeaker Design