I don't think this is true... you'll get more net airspace from the same gross volume but only because separate chambers take up more volume. I think the notion just stems from the fact that when many people upgrade from a single sub to 2 subs, for example, they don't usually want to build a box that is twice as large so they'll just make it a little smaller than double even though it changes the properties of the enclosure/system.
I could be wrong, but I've never seen any evidence of why multiple identical subs in a common chamber would require less airspace per driver.
I could be wrong, but I've never seen any evidence of why multiple identical subs in a common chamber would require less airspace per driver.
