sealed? ...

 

Yep, sealed simply refers to an enclosure that has no ports. The subwoofer is entirely encased by the box. This type of enclosure tends to be the most punchy, and usually the best sounding, but lacks some of the loudness that a ported (or vented) box would have. Sealed boxes are usually quite a bit smaller than a ported box, since the port takes up extra space. The reason I suggested the sealed was because you have 3 very good woofers with plenty of power. And having a ported box with 3 subs would take up a lot of space.

Ports are implemented into a lot of enclosures to enhance the output of the subwoofer, usually at a certain frequency. Ports can be tuned to achieve different results - a lower tuning frequency of 30Hz is for sound quality, while a higher tuned frequency of 50Hz would be used by people who participate is Sound Pressure Level (SPL) competitions. The dimensions of the port is what determines the tuning frequency. There are calculations that determine how a particular port will work, based on its dimensions.

I'd at least try a sealed box. They cost less to build as well.

 

^^that's not true...vented/ported enclosures can be just as tight, punchy, and clean sounding as sealed boxes. They have to be made properly, and tuned correctly for the drivers being used. Yes, they are more difficult to build, they do take up more space, and are much more efficient....but, you have a full size van, and 3 high output subs...why not get the most out of them? Ultimately, it depends on your space allocation. If you have the space, build the ported box, try it with your 750 watt amp, then close the ports off (rubber plugs or wood plate), try it, adjust the volume inside to the optimum sealed volume by placing blocks of wood or styro foam inside (to reduce internal volume to spec)...try it again....keep it the way you like it best! A ported box can always be turned into a sealed box...not the other way around (unless you purposely build it extra large with ported possibilities in mind). With the ported box, that 750 watts will probably be enough to get very loud.

 

^^^ That's not true...

I'm kidding. Sealed boxes tend to he a little tighter. That's not to say that a ported box can't sound tight.

Definitely give both configurations a try. And stick with the one that sounds best to you. Denonite's method of stuffing the ported box, for a sealed volume, will work fine. Try it out.

 

^^^That's true!! lol...yeah if you have the space and the time..and the inclination...it's also a good way to find out what type of sound you like. I actually like both ported and sealed systems. Depending on the space i have, the power available, and the driver's being used (if i get a killer deal on a particular brand/model)....then I decide which way to go.

 

I'm currently running an Alpine TypeR on about 600W @ 2 ohms, in a sealed box.
The box was originally made for my TypeS, but with the amp's output of 420W @ 4 ohms, and the sub's RMS at 300W, I was getting a nasty sound when hard bass hit. That was with the gain at minimum and setting all set low.
At first I wasn't sure if it was my box that was the problem. Dropped the new TypeR into it, and I've had no extra noises what-so-ever.
And this little thing produces enough bass for me. I'll be a bit happier once the sub is fully broken in, and I can push it a little further.