Ok..here's the scenerio...

I want to build a subwoofer box that will hold my two 12" Rockford subs AND be as small as possible (but still large enough for the subs to fire properly). Idealy, I'd like it to fire upwards so as to keep the box as short as possible. If it's firing upwards, I'll need something to cover and protect the subs from debris/cargo. This will be a sealed box. What could I use to cover the subs? Plexi-glass with holes, perforated steel, fabric? Any ideas?

Another idea would be to have the subs fire downwards, toward the floor of the truck. My question is, would that muffle the sound too much?

 

I've seen a lot of home audio speakers with the sub firing downward. The box would have to have enough port at the bottom making the box 4" or 5" taller. That's the way I'd build it. It seems like that would protect the sub the most. Or if you're firing them upward just go down to your favoite car audio place and get some speaker grilles they are way inexpensive and they do the job. That way the box would be as short as possible.

 

I agree with Kev....but I did build one with the woofer mounted from below the wood surface, covering the opening with wire mesh, then covering that with carpet. The mesh kept anything from hitting the woofer and allowing sound through. Worked great.

 

Well with sealed enclosures, you cant have your cake and eat it to, so to speak.

The 3 variables are sensitivity, low bass response, and power handling. A very small box will not be very sensitive, and wont have low frequency bass response without a ˟˟˟˟˟LOAD of power. The converse is true of a big sealed; high sensativity, good low bass frequency response, but also very low power hanlding. This is known as the Hoffman-Iron Law.

This simple little law drives transducer manufacturer's nuts, particularly when you have the consumer market screaming for a very small, very sensitive sub, with an ungodly powerhandling. No such beast exists or ever will... One that fills all 3 niches is a compromised sub.

So build your sealed box according to the power the subs will be recieving....

ps - fire upwards, not down.

 

Ah, well then...
I scratched the idea of them firing UP, so they're like they used to be..firing out the rear. Each of these subs takes 425watts RMS, and I have a very good feeling that the box I'm building is far too small. I guess only time will tell. If it sounds bad, I'll stuff some polyfill up in there.

Thanks for the ideas guys.

 

Did you check the companys specs on how many cubic feet the subs will need in a sealed box? I did on my JL 10wO and in a sealed box it was less than one cubic foot (like .75 or so). They even listed the size for the enclosure sealed or ported. Definately check into it if you haven't!!

 

remember that you get the most possible cubic volume per box surface area when you build a cube. The more elongated you build, the less volume you get with the same material. I don't know whats under the matt in a runner, but I have seen a friend build a ledger from spray foam around the perimiter of the trunk. He then cuts exterra (marine grade mdf) in the shape of the rear floor and flush mounts the subs firing upward. Having a spare tire well gives just enough volume for two twelves, if the new floor is elevated a couple inches from orig ht. He then uses hd speaker grills to protect the subs. the result is having great bass without sacrificing any storage at all.

 

Here's what I did... only for 1 sub, but you could use the same idea for yours...





It's kinda hard to see, but in that second pic, I built a false floor over everything, and put a metal mesh grate/guard in to protect the sub. The metal grate is plenty strong (I can sit on it and it doesn't budge) to keep things off the sub. Add some carpeting (which I haven't gotten around to yet) to keep dust and dirt and such out. The only other thing to worry about is moisture... but that should't be a problem for most people.

The grate was $20 for 2 from Circuit City... very strong. Let me know if you have any questions. I can try to get some better pics for you if you're interested.

 

doesnt having subs firing upwards make the cone loose? my friend told me that the cone will tend to sink lower and cause it to mess up a little... dont know if thats entirely true, but i was just curious.

 

No, a sub's CMS ("looseness") will only change according to how hard and long it is played. Given time, most subs will tighten back up if left unplayed for a period of time. If the sub is made to be loose through lots of abuse/use and it's facing up, then yes it will be slightly depressed into the basket. The effects of that are negligible at most.