Has this been the trick employed by those tiny Bose speakers that got popular in the 90s?
I remember being in some kind of demo truck as a kid, where they were showing a scene of Jurassic Park (from a Laserdisc!) and they had these big speakers left and right in front and small ones behind, and were blasting the audio at pretty high volume so you would think "surely the thick base is coming from those big speakers up front". Then, half way into the demo, they would open up the "speakers" in front of the audience, revealing the surrounding wood to be fake and the actual speakers inside the fake housing being just the same tiny ones as those located in the back.
I remember being very impressed by that demo. By the speakers, but actually even more by that Laserdisc ;-)
The trick the Bose Acoustimass system uses is a form of resonance. While it is proprietary, it is fairly easy to build for yourself. In the 1980s, Popular Science (or Mechanics, I forget which) had a review of these speakers, and they told the "secret":
Take your small bass or midrange speaker (something with large excursion of the speaker diaphragm) and place it between two "tubes" that are in a 3:1 ratio. The tube on the front-side of the speaker should be the longer of the two.
So - grab a cheap 4-5" woofer and a carpet tube. Cut the tube into a 3 foot length and a 1 foot length. Put the woofer between the tubes, sealing it up well, with the front of the woofer firing down the longer tube.
That's it. It actually works well. I built one myself using junk as a kid back the late 1980s, after reading the article. What Bose did was then "fold" the tube so it could easily fit into a box. There is probably a ratio also between the volume of the tubes and the width of the driver, among other things, but the basic idea described above will work rather well. You could even do the folding trick with an actual wood enclosure if you can calculate the lengths and such thru the curves properly.
It's similar to a bass reflex or other ported style speaker, and it scales up and down rather well (see the Bose Wave radio - IIRC, it used either a 2.5" or 3.0" single driver for the bass). The downside is that it doesn't work over a wide range of bass; the bandwidth is somewhat narrow (it is possible to offset this, though, with an EQ and amplifier, to boost those lower frequencies - plus midrange speakers in the "satellites").
I saw that demo too, though it was in a store and I don't remember a JP scene being used. Bose were always shite at accurate sound reproduction, but great at making things sound good. And nothing noise-cancels like a pair of QuietComforts.
I remember being in some kind of demo truck as a kid, where they were showing a scene of Jurassic Park (from a Laserdisc!) and they had these big speakers left and right in front and small ones behind, and were blasting the audio at pretty high volume so you would think "surely the thick base is coming from those big speakers up front". Then, half way into the demo, they would open up the "speakers" in front of the audience, revealing the surrounding wood to be fake and the actual speakers inside the fake housing being just the same tiny ones as those located in the back.
I remember being very impressed by that demo. By the speakers, but actually even more by that Laserdisc ;-)