ported --> vented enclosure? Or just sealed?

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ported --> vented enclosure? Or just sealed?

Hello all,

I'm currently trying to design a sub box for my truck (99' nissan frontier ext. cab) and need some help with my plan. What I would like to do is remove the two jumper seats behind the front seats and install custom enclosures in that recessed area. The area that is available once the seats are removed is roughly 12" x 4.75" x 20". I plan on extending the depth of the enclosure another 1.25" to make the enclosure 6" deep and provide a 5" interior depth. At the lower end of the enclosre, I plan on extending the side of the enclosure out 13" so the sub is mounted at an angle. The total internal airspace will be roughly .8 cubic feet. The driver I plan on using (Diamond Audio CM310D2) specifies that an ideal sealed enclosure should be between .5 and 1 cubic feet, and a ported enclosure should have an airspace of .75 cubic feet. Since the airspace of my intended enclosure is close to the requirements of a vented setup, I'd prefer to go this route. My problem though, is that the port size and length specified from the manufacturer is a 4" diameter port extending 13". Due to the enclosure being recessed into the body of the truck, I will be unable to use a port, unless I have the port aimed at the top of the enclosure and ultimately at the frame of the truck. What I would prefer to do is use a square vent that occupies the top section of the enclosure. I'm just not exactly sure on how to convert a port to a vent. Any and all help would be greatly appreciated with this. Whether you can point me to a source where I can find this information, provide the exact specs I need, or even attempt to persuade me to just using a sealed enclosure. I'm open to all comments and suggestions, since none of this is set in stone (or truck) just yet.

thanks.

-Geoff
 
It depends on how do you like your bass. What amp will you use?

You're in a truck so deep bass won't be a problem, a sealed enclosure will be enough to achieve flat response down to 20 Hz and even lower, but do you want that? Or you prefer sky high SPLs?

Why did you choose this driver?
 
i picked these subs for no better reason then it's the same brand and line as the components I'm using in the front. Maybe it's an OCD thing, but I just prefer to have all my gear matched up. As for what amp I'll be using to push it, I couldn't say. Right now I have a 4ch. DEI amp to power the front speakers and then bridged for the sub. My ideal setup would be to get the DEI 1100D for the subs, and then keep the 4ch. amp for the front mids and highs. I have 11ty billion idea's about what I wanna do with the truck. It's just making up my mind and sticking to it that seems to be the problem. so speaking of ideals, I'd like it to be loud... but clear. I'm past the point of blasting my stereo to get attention. But it doesn't mean I don't like loud music anymore. :) and my interests vary from hip-hop to house to jazz and swing and ska and punk and metal. I'd just like a setup that will be able to accomodate all of my musical tastes.
As of now, I'm not even sure if I would be able to use a ported enclosure because of another design change. But I'm still curious about how to go about figuring out the calculations for a vented design.
 
You can go vented if you want to, it will be much louder down low, but less tight around tuning frequency.

Inside a car you have very high room gain, you could design it flat anechoic but inside your car you'll be 20 dB louder at 30 Hz than at 100 Hz. This problem can be corrected with a EQ, but you might even like that low end boost, I don't know how you like your music.

You would need someone to find a car room gain curve that is compatible with your pickup, without it it's difficult to design something.
 
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