Why are you considering the Q series? I always thought they were a terrible design.
Correct me if I’m wrong… But when you’re using passive radiators, the radiator is recommended to be twice the surface area of the active driver, which would be fine if both the passive radiators KEF is using in the Q towers were in the same chamber as the woofer, but they are not. KEF uses one radiator for the mid-woofer (Part of the Uni-Q or what have you) in the top chamber and the other radiator for the woofer in a separate lower chamber, so the surface area of the radiators is equal to it’s corresponding active driver.
That aside, the passive radiators are both facing in the same direction as the active drivers which causes them to be out of phase with the active drivers. Then, ON TOP OF THAT, the two chambers are different sizes, so the radiators are reacting at different times because the air pressure is different in each cabinet. So now you have the two active drivers moving forward as a positive signal is applied to them, the two radiators now both move inward, BUT at two different speeds because of the different amounts of air pressure in the different sized cabinets. In slow motion this speaker must look like total chaos.
Now… In THEORY,
radiators act as ports, not as cones, so, in THEORY phasing should not be a
problem. But I just don’t buy it. I don’t see how any of this is a good
design. It looks like a mess that
someone threw together. The Q series
bookshelves all look great to me, but I have no leads on their thought process
when it came to turning those bookshelf ideas into floorstanders. Somewhere, something went terribly
wrong. Or maybe not, maybe it's fantastic and I just don't understand it.