Compact Sealed Sub Enclosure Under False Hatchback Floor

[GoMax]

I am building a 0.5ft^3 sealed enclosure for a sub I ordered. (12" Sub)
Enclosure will be 17.5" x 20.5" x 4.5". - at least that's my current plan.
This SHOULD allow me to install the box under the false floor (since I believe there is about 5"-6" of space between the actual floor and the false floor.

I know I can remove the spare, or even flip it over, but for now, lets assume I keep the spare as it is....

My Question:

Will there be any issues with the sub firing upwards, with only ~1" between the top of the subwoofer box and the bottom of the false floor?
Based on my understanding - there should be no reason to put holes in the false floor - given the ~60Hz crossover point for the sub.
Since I use the back to carry bikes, stuff, etc, I don't want to expose the sub face, or have dirt and gunk fall onto the sub!

Is the false floor gonna buzz like crazy?

Thoughts?

 

[TaylorFade]

First of all... fantastic choice of sub. You're going to love that thing.

Your only concerns *may* be diminished output from being under the false floor and perhaps some resonance from the actual panel. Neither of which will be terribly pressing, imo.

Sub bass wavelengths are sufficiently long enough not to be hampered too badly under there. And it's not exactly sealed up tight as a drum so whatevs. And that panel is pretty rigid and seemingly "dead" enough not to vibrate audibly.

I think you will be pleasantly surprised, but keep up updated because this is basically my plan when I get around to it.

 

[GoMax]

I'm sure I can mitigate the resonance of the panel by putting some dampening materials on the underside if needed.
I "might" be able to decrease the 4.5" dimension to 4.0 using 1/2" material (rather than 3/4"), but I'm concerned it may not be rigid enough.
Of course, I could put in some small dowels to increase the rigidity of the box, but I'm not sure if it will be a good tradeoff. - especially given how small the box is already.

Once I can actually measure the under panel space, I may have to adjust my plan.

 

[TaylorFade]

I'm sure I can mitigate the resonance of the panel by putting some dampening materials on the underside if needed.
I "might" be able to decrease the 4.5" dimension to 4.0 using 1/2" material (rather than 3/4"), but I'm concerned it may not be rigid enough.
Of course, I could put in some small dowels to increase the rigidity of the box, but I'm not sure if it will be a good tradeoff. - especially given how small the box is already.

Once I can actually measure the under panel space, I may have to adjust my plan.

With such a large baffle, bracing is going to be a good idea anyway.

I've measured it and it's right at 6" to the bottom of the 'nook' the false floor sits in near the back seats.

The sidewalls you see on this mock up are 5".

 

[GoMax]

According to Nick, having 1" above the speaker will be tight, but it will still work, even with the sub at full extension.
Based on the details from the site, I put together the shortest (recommended) enclosure.

This gives the sub 1/2" air gap between the sub bottom to the floor of the enclosure.
I don't know the height of the Surround above the gasket, but its probably only a few mm.

This assumes 3/4" (19.05mm) material.
In this case, which would be better, the rectangular shape, or the more square shape?

 

[antarctica24]

1st there will be no loss of sub performance being under a 1/4" floor. There would be no loss of sub performance if the thing was firing from behind a 6" piece of foam rear sear installed in a trunk or a metal firewall for that matter. This is what you hear when you are sitting at a stoplight you can clearly hear the idiot 4 cars behind you. Subs=long sound wave.

You will need to secure the false floor. I am doing the exact same thing but with 2 10" subs. You can secure it a couple of ways but the best option is to take a couple of pieces of dynomat or such and secure to the back of the panel. You need to add mass to the panel. Then using a bungee cord or whatever other method you want, secure the panel tightly down. Otherwise you will hear it vibrate.