He does claim 550cc, but then he compares that to the 255cc for the DeltaliteII 2512, which is a Klippel measurement, so I assumed his was a Klippel measurement as well. If he's using one standard for his speaker then comparing to another speaker measured with a different standard that's troubling. It's kind of like saying this car gets 31 to the gallon of gas and that car gets 50 to the gallon, without mentioning the 31 was referring to miles and the 50 to kilometers, so they're actually the same. Now that you've brought it up I'm curious as to the actual frequency response of his twelve. He claims that it's similar to a 12HO, but with the xmax of a 12LF, and you can't have it both ways. At least you can't as far as I know, and if there was a driver that could do that economy of scale says it wouldn't be made available only to a small boutique manufacturer.In a thread last year Alex claimed that his woofer has 10% more displacement than mine. I asked him how he measured x-max. He replied "We use voice coil overhang plus magnetic gap / 4..."
I plugged the figures for the stock 3012LF into Alex's equation and got: 545.5 cm^2 x (7.78 mm + (9.1 mm/4)) = 548.5 cubic centimeters. Alex claims 550 cubic centimeters of displacement for his woofer. As you can see, if we calculate the displacement of my stock Kappalite 3012LF using his equation, we get almost exactly 550 cubic centimeters.