i am looking in to buying 2 new alpine swr-1223D subs and i am trying to figure out what kind of box will work the best for them. sealed, ported??? anyone know how to figure this out or know what works the best.
Thanks
seth
Use the optimum vented recommendation in your owner's manual. Build a great quality box, damp the metal in your car, power them cleanly and you'll have a fine set of subs using those.
The result, when using two of these subs and going with the manual's box recommendation, would be: net interior volume for the woofers alone = 3 cu ft. That doesn't count the volume taken up by the MDF or the port structure, or any braces incorporated into it. As you see in the manual, the given specs of 1.5 net cu ft is for one woofer.
The port would look different, a bit. Enlarge the port opening to 12" X 2", and make it 15.67" deep for a tuning freq of 33 Hz. F3 looks nice at about 29 Hz. That's the starting point where the low end of the music fades in intensity, and that's a good number.
Work your box dimensions out so that 1, it fits your car. And 2, that you have enough space to work with that you can realize the total 3 cu ft net airspace after building the port and accounting for the subs, the port structure, and other things in the box that take up space.
If you can't find that much space for your box, you will have to do enough measuring and figuring to come up with a total cubic inches, or 3-dimensional space in inches, that we can work with. With any change in internal air space is a corresponding change in port dimensions. You can't guess at that.
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.