Sub woofer box size??

[Blown 472]

is there a formula to figure out what size box you need per size of speaker?

[79centurion]

Depends on the speaker. Check with the manufacture on what cubic space is needed.
Dan

[thmper321]

Usually speaker manufacturers have a list of box specs included in the box. There are three different types of enclosures that are used the most.
Sealed - The smallest of the three. Its very forgiving if the size is not exact. It will typically play lower frequecies in a controlled environment like a car that will act as a way to "load" the enclosure. In a large environment like a house or in a boat you have to be careful about creating a way to load the enclosure like under the bow or downfiring in the back seat with a slot on the bottom.
Vented - Larger than the sealed. Not very forgiving if the air space or the port specs are not right. Plays 3dB higher than the sealed enclosure within the tuned frequency. Anything lower than the tuned frequency drops at a higher rate than the sealed enclosure thus you have to make sure the tuned frequency of the enclosure is very low, about 30Hz, to keep from blowing up the woofer. This enclosure does play better in an open environment than the sealed enclosure.
Bandpass(A sealed box playing into a vented enclosure) - The largest of the three enclosures. Also not very forgiving if not designed and made correctly. This is the most efficient enclosure of the three as well. It self loads the best of all three enclosures which means it plays the best in an open environment and is used as often in home theater applications as the vented enclosures. One has to be carefull not to burn up the voice coils with this enclosure due to the fact it is difficult to hear when the amplifier is clipping.
If you are building the enclosure yourself than I would say to go sealed. If you are having the enclosure built than the other two would be best if room allows. Also Sealed I would recommend 12" or larger and the other two you could go with 10" woofers.
Most retailers have box programs to help or you could even call the manufacturer and they could help.
Sorry for the ramble.

[It's all Good]

Here is a site that offers enclosure dimensions:
http://www.the12volt.com/caraudio/boxcalcs.asp

[Blown 472]

Thank you.:)

[Tom Brown]

To design an enclosure, you're going to need to know the Qts and it would be nice to know the f3 (frequency at which the driver is 3 dB down). These values are not directly related to the diameter of the cone.
You can look your speaker values up and use those listed by the driver manufacturer and ge tpretty close but there are gains to be made by measuring the specific drivers you plan to use with Nexus, LSP CAD, or whatever.
Something to keep in mind when thinking about how carried away to get with driver selection and box design is that every three dB of efficiency you can achieve on the speaker side will allow you to halve the power required to create the same sound pressure. In other words, if you 'just don't worry about it too much', you will either need to break out your wallet and stump up for more power or just accept less output.
Personally, I much prefer to fuss with speaker efficiencies and save a ton of money on the power side. It's less impressive visually than having a trunk full of expensive amplifiers, though.