Something's a bit loose inside, plus there's some rattling going on during loud bass, so I decided to open it up to see if I could secure the bad noises.
Unfortunately not much in the continuous bass department. It's only rated down to 130hz, and with my heavy use of EQ on my phone to knock down the mid around 400-1k and significantly boost around 150hz, partially due to how Id EQ the tracks anyway, not much volume is left to overcome ambient noise.
The back pries off, little glue, mostly friction fit pins.
Passive radiator being on the back makes it not as effective outside unless a little port was added to send the bass out front. It seemed tuned around 95hz and the total resonance below that was around 75hz, which matches what I heard with the bass dropping off below 120, and rapidly below 75.
The buttons might need to come out to clear components on the board, but I figured out everything pushed out the back by design, and I'm not there yet. I used a tiny screwdriver to reach in and push up the 4 clip tabs.
The hard part is they hid screws behind the very firmly glued in steel grille. Luckily only the corners were glued with a somewhat stretchy glue, but it was quite difficult to get off without much damage. Looks like paper cones with plastic caps.
Done for the day
At bass frequencies the wavelengths are long enough that they're omnidirectional for something of this size, and they'll add constructively whatever side the passive radiator is on. A benefit of putting it on the opposite side of the woofers is that some of the forces cancel when they're all moving a lot. Small speakers can move around quite a bit on whatever they're sitting on when playing low, so force cancelling can be helpful.
The open area looks a little low for the plastic grille on that side, but predicting how that will impact bass is less straightforward. You'd hope they tested its performance.
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Yes there may be some leaks around one driver, it's sound changed as I pressed on it's basket rim, and it seemed different than the rattle, which may be the battery in part, so I suspected a possible leak. They did add glue to seal the screws.
The bass sounded much better with my hand cupped to redirect the PR sound to the front. The back cover is very restrictive, at the time I didn't know there was a PR, I thought it may have been an open baffle. I think the only usable bass this has (in the 75-150hz range) is too directional to bend around without much loss in magnitude.
I may ream those holes out a bit, they look bigger on the inside than outside, and maybe make a little port attachment to redirect the PR sound to the front.
A rule of thumb is that a driver becomes directional when its effective piston diameter becomes larger than 1/3 of a wavelength (or 1/4 depending on who's talking about it - it's a gradual shift so open to interpretation).
Some examples, plots, and animations also at this link:
https://www.holosonics.com/fundamental-limitations-of-loudspeaker-directivity
"For a small source ¼ of the wavelength, the sound field is again omnidirectional. . . . notable directivity exists only when the size source is much larger than the wavelength."
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Cupping your hand over the passive radiator isn't really a fair comparison if you are trying to demonstrate an effect related to its location only. Restricting the radiation space or changing loading of the passive radiator may have been the primary differences you heard. At near listening distances some of these effects are exaggerated.
Hopefully I'll get back to this this weekend, but regarding air leaks, this should have some minimal extent of an air leak, otherwise excursion of the various diaphragms involved would be misaligned with altitude, barometric pressure, and temperature changes.