Sealed box, not going to happen considering it'll probably be at least 10db down once it gets that lowPorted box tuned to ~10hz?...who's going to build something like that? And with a tuning that low, there's still a peak, but it's a ways down from the 0db reference point.
I guess I'm trying to say that the
10 db down for sealed? That would depend on the enclosure alignment, resonant freq response of the vehicle, etc.
You dont need to tune to 10hz to be able to hit 10 hz (with authority) in a vented system. As an enclosure designer, you should understand this.
You are making way too many assumptions, and using those asusmptions to extrapolate the conclusion that a 12 cant play 10hz 'with authority'.