Well, looking closer, it appears the subs are in hard enclosures that appear to be covered with fabric. Perhaps prefab cabinets for a tuck, or similar?
Now, this looks like an ambitious rig! Kudos on the over-the-top attitude!
What's happening with the subs? Are those arrays home made? It looks like they are encased in foam. Or, is that some dense, dark concrete, like material?
