bookshelf speaker design I've been kicking around
Labyrinth loudspeakers use a tuned pipe that is 1/4 the wavelength of the Fs of the driver in free air. The pipe is internally lined to supress the harmonics of the fundamental frequency with some absorptive material. Like all esoteric speakers, they have fatal flaw.
My take woudl be a traditional folded approach to keep the enclosure "looking like a speaker" and not some coiled abomination. My idea is a series of cuts in the surface of the internal baffles with a table saw to create a a washboard effect. The cuts could be random or worse, mathematically calculated depths to achieve an absorption/dispersion hybrid, but perhaps I am getting ahead of myself? Anyways, these ridges will then be stuffed/glued with small peices of felt at random (or mathematical (arghh!!! stop it!))lengths so that they stick above the surface much like blades of grass or hair on an arm. Hopefully this will aid in absorption beyond just a flat, reflective surface covered with felt.
Design of this is harder than I initially thought if you start with external box dimensions in mind. The pipe should maintain the speaker cone area until the the port outlet, so you really can't just invent volumne to make that happen. I'm going to need to play around with it. The driver choice places a major role here, since the only design criteria I have to work off of is its free-air resonance.