Haunz - yes, moving mass effects box design, but a nice light cone (with a similar motor to a heavy-coned woofer) is going to respond faster. If you are moving less cone mass, it's going to respond faster to changes in input signal. Why do you think people like Image dynamics and Elemental Designs woofers so much?

As far as the 25Hz tuning - I'd have to run the numbers again, but I don't think it want's to be dragged down that low. If you are looking for extension, then a sealed enclosure is the way to go.

 

Above the tuning point, vented boxes handle more power.

If you are looking for increased response where you can actually hear it then a vented box is superior to sealed.

I would keep the vent tuning to the 30-35hz range for this woofer in 3cuft.

 

Haunz - you believe what you want. It's irrelevant to this discussion.

Dukk - you are right about power handling - you can certainly make a driver in a vented box handle more 'excursion limited' power through the usable range.

 

Yes - there are lots of other factors that are equally important to the ultimate performance of a subwoofer. Gap spacing, winding material and density, T-yoke and top plate geometry, magnetic field density and focus, suspension geometry, suspension linearity and so on. All have an equally important effect on performance.

so, Yes - you can have a low-mass coned subwoofer that sounds crappy.

Yes - it is a generalization.

But - in most cases - with properly designed drivers - the lightweight ones sound pretty damned good - at least, the 10 or so of them I've heard sounded nice and tight to me. Image Dynamics, Elemental Design, this particular series of Clarion woofers, Pioneer PRS 12, Focal Polykevlar, and so on. I had a list for a while - can't find it now.