Thanks for the reference to that interview - hadn't seen it before.
RV worked out his theory on a model you rarely hear about, in the 1980s - the Vandersteen 4 and later 4A (which as a significant improvement over the 4). Didn't make many - something like a couple of hundred pair, I think, and they now come up for sale at ridiculously low prices because no one knows what they are and they were never reviewed.
I liked my 4As so much I still have them after a quarter century, albeit in my 3rd system, because I just couldn't bring myself the sell them. If you ever see any for sale, give them serious consideration as they still provide a bigger slice of audio reality than many much more current speakers.
Like his current models, they have an on board sub (a push/pull pair) with a high quality cap to roll off the bass to the other drivers, and the sub bass requires separate power amp(s)
