Questions about building a sub enclosure

[soundNERD]

I'm building a home subwoofer enclosure for a person I know and need some help with a couple of questions.

The requirements from the person I know were deep, powerful sound. He's currently got a lousy Definitive Technology 8" ported subwoofer, which isn't even close to enough for the basement it's in.

So, to meet his requirements, I decided on a sealed enclosure with a 15" driver. It will be built out of 3/4" MDF.

My question is once we decide on a driver, and calculate the optimal box size (will tune to about 40-50hz for the depth he wants), what happens to the frequency responce of the box if I made it larger than that? What if I made it smaller?

Also, what do you guys think about purchasing a 15" passive radiator for added power and depth?

Finally, I was thinking of an infinite baffle design. The basement has a room about 7ft wide by 12ft deep where the sub will be going anyway, and doing something like this looks like a really good solution: http://white.hometheatertalk.com/tips/ib.htm - especially to get not just the volume but also the depth of the sound to really feel it when something blows up in a movie or something. Only thing I'm worried about here is that the room it will go into has a door nearby, would that mess up the sound? what if the door was open?

Thank you for all of your help,
Mike

 

[pjanda1]

I'll chime in as you seem to be sliding down the page without any responses. It sounds like you are open to many different possibilities. The biggest initial question then is, what is your budget? Beyond that, you may be able to sort through some of the options by doing some searching and reading on this forum. A sealed sub is not "tuned" to any specific frequency like a vented design, but the size of the enclosure greatly influences the sound. A passive radiator works essentially the same as a vent, and both need to be specifically tuned and used with the correct driver. If you want to avoid technical details you may be best served by picking a driver and building the manufacturers recommended enclosure size.

Here are some good 15" drivers.

http://yellow.mynethost.com/~bv1263...id=53&osCsid=2258579755fc1c9590a9563568950f0e

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-420

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-190

Both companies also make drivers specifically built for infinite baffle applications. It sound like some Adire Audio drivers may be appearing again as well. All also have quality plate amplifiers. Perhaps the best deals on plate amplifiers can be found at:

http://www.rythmikaudio.com/nonservo_product.htm

However, you may find the 500 or 1000W amps more attractive with such beastly drivers.

Finally, these guys offer a sampling of different companies products,

http://www.acoustic-visions.com/~acoustic/products/subwoofer_drivers/index.shtml



good luck,

Paul

 

[pjanda1]

P.S. www.diysubwoofers.org is a good place to find some condensed basic knowledge.

Paul