This is one of Paul Bartons early designs, refined using the anechoic chamber and test equipment at the National Research Council Lab in Ottawa.
They used a common Philips 8 woofer, but one was blown when I got the speakers. I've upgraded them with what look like the same Philips woofers, but with much bigger magnets, and squiggles of black toothpaste on the cones. They're actually hand calibrated versions, a matched pair intended use in a pair of Wilson Audio WATT speakers, highly respected audiophile speakers costing thousands of dollars a pair. I've never heard them, but know that Dave Wilson, who was an early reviewer at The Absolute Sound magazine, could've chosen many excellent woofers, and chose these.
They aren't going to be exploited to their fullest in the Passif 2s, but the system does sound great...as good as any I've heard that use the same classic Philips tweeter.