[ric rice]

Here's what I did to save space on my sub install. Made a new floor. Amp is under the passenger seat. 12 inch pioneer sub with grill off a central a/c unit I got out of the trash. Turned spare tire upside down. Sounds good.

 

[ric rice]

Picture that did not post first time!

 

[Slorocket]

That so cant be enough air space for that sub...

 

[markio]

that floor looks sick!

awesome DIY

agree about the air space

 

[Damaged]

Looks good, how does it sound?

 

[BrickPig]

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.