[nickbatz]

EGG ON FACE.

After removing the crumbled foam, it turns out that these aren't passive radiators at all, they're 12" rear-firing woofers!

So these are sealed tower boxes with 3-way speakers on the front - including what looks like a soft-dome tweeter with a plastic cage on it that I'll have to look at more closely to see whether it wants removing (i.e. I'll have to see whether it's just for protection, as opposed to being some kind of wave guide).

The cones are moving freely, which is enouraging.

Sorry for the false passive radiator alarm. Will pick up a couple of surrounds from ebay and make these things work.