Has anyone thought about taking the basic idea of thrusters, and improving them? Put in some acoustic foam, thicker walls, and a crossover, and you could really have something...I think
I've always enjoyed trying to get the "cheap" stuff to perform better, so I'm glad someone asked.
If the enclosure didn't include any damping material, adding some on at least one long side and a portion of the rear panel directly behind the dual woofers/full range drivers
*, should help eliminate a good chunk of boominess.
As far as an improved crossover, if *I* was going to build one: if there wasn't one already present, an inductor on the woofers (in the 2-way version) would help reduce intermodulation distortion, which is created when the shared output of the woofer and the tweeter - which happens in their crossover region - interfere with each other, a little bit like mixing vinegar and baking soda.
FYI: using an inductor will create a 6dB per octave roll-off, the "gentle-ist" you can get with conventional components. Anyway....but if the woofers were designed carefully enough, their natural rolloff will act like a built-in crossover (usually called a "mechanical crossover") and an inductor isn't really needed. Many speakers from respectable manufacturers over the years have used, and
still use, a 6dB/octave xover, though they might also include some extra components to reduce the driver's output to match the other drivers' output level or "shape" a driver's response to better fit the overall system's desired sonic personality, but it will still cause a 6dB roll-off.
A more sophisticated xover can create a 12dB/octave slope for the tweeter, which
should increase its power handling capacity and lower its distortion at the same time.
Bracing the cabinet is a good idea, though I wouldn't overdo it because the volume taken up by the brace(s) in turn changes the volume of the enclosure and
that directly affects the operating characteristics of the woofer+passive radiator system. Personally I would stick to just one front-to-back brace (between the front baffle and rear panel) consisting of a skinny wooden dowel, say around 1/2" in diameter.
* Note!! With a bass-reflex design - and a passive radiator-equipped speaker is included in that category - it is generally
not advisable to cover every interior wall of the enclosure with damping material. Otherwise the port/PR system will not work as well as it should.
