That so cant be enough air space for that sub...
agree about the air space
It depends on the sub but you guys are probably right. Looking at
Component Subwoofers Comparison
the shallow sub needs a sealed box of only 0.65 cubic feet of volume, but the other 12" subs need 0.8 or 1.25 cubic feet of volume. ric rice has a 12" diameter tube so at best he gets 113 cubic inches of volume for every inch of depth. If he has a 10" deep tube then he gets 0.65 cubic feet of volume. So if he has the shallow sub, maybe
...but like you, I doubt he has enough air volume for the sub.
"Sounds good" is subjective. As long as he's happy...
ric rice can improve the bass response by making the enclosed volume bigger, for example he could use some of the volume above
the spare as well as in
the spare. The shape of the sealed box is not as important as the volume of air contained.