what is the best frequency to tune sub

I am a neewbie here so please forgive me if I posted in wrong location. I did do a forum search and didn't see what I'm looking for. For Christmas we bought our son a new swr1243 d sub. His current set up is a power HX2 10" in a box with 1.92 cbft, includes disp.for woofer, and a 3"port 9" long. His truck is a 2003 Dodge quad cab not crew cab. We built it together and it fits his back seat like a center console as these trucks are boogers to put a box in. Using the new sub he will have 1.89 cbft and I have no idea what I should do to the port if anything.We also got him a new amp and a 1 farad stiffening cap, the new amp is an infinity 611a and his current one is an MTX 4250d. His Power HX2 is starving on this little amp and it hasn't helped that my math was bad and the box is a bit big for the current sub. He listens to mainly rap,big surprise @17. The questions after my ramblings are the following: 1: What is the best tuning frequency for this new sub with a box of 1.92 cbft? 2: Anything else you audio wizards would recommend is greatly appreciated? They said loud music would damage my hearing,what do THEY know.What was that, did you say something :)

The easiest thing to to is check the owner's manual for your woofer.  On page 5 it states the 1243D should be tuned between 27 and 33 Hz.  I'd shoot for that range.Support the12volt.com

Thank you, I did a google search and got about 5,000,000 results. Use the FS don't use the FS, blah,blah,blah. It was very mind numbing at best. His box is currently tuned to about 25 hz so I will change the port and aim for 30. Thank you again and Merry Christmas. Any thoughts on changing the size of the box? and if I fill some of the box to make it a little smaller like 1.50 cbft what would we gain versus lose?They said loud music would damage my hearing,what do THEY know.What was that, did you say something :)

That woofer wants about 1.9 cuft so I wouldn't change the size of the enclosure, just the length of the port if necessary.Support the12volt.com

rooferrobbie, don't use fill to compensate for lessened volume in your vented enclosure.  If you use polyfill at all, glue it to the walls but don't make the box smaller.  Build a vented enclosure to the modeled specs.Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Thank you again for your input. I don't want to make the box smaller I was only considering it if it would help the sub perform more dynamically. The specs for the Alpine say that the ideal size is 1.5 and I am a touch over that. His current set up sounds great to me but we have different tastes and it's his ride. I really want to blow his socks off as he has had a really hard year and still knuckled down and been a great young man in the face of extreme adversity. He wants bass that will make your teeth rattle :) I would love to have a vented box but the problem arises in trying to build one that will still allow him the use of his backseat. His current box is form fitted and specifically built to sit in the middle of the backseat and looks like a console that passengers can use as an armrest. It fits the contour of the seat from the back and all the way down to the floor. The truth is I don't have enough trust in my abilities to build a vented box that will perform properly and still fit the backseat as his current ported box does. If I can figure out how to post pictures I will try to put one up of his current box so you can see it. Thanks again for the advice to both of you, it's hard to find folks that are willing to give of their time to help someone just for the sake of helping so it does mean a lot. I plan on making some financial contributions to this site as soon as we get through Christmas.They said loud music would damage my hearing,what do THEY know.What was that, did you say something :)

Indeed, if you add poly-fill it will make the enclosure function as if it was larger, not smaller.  If you want to reduce the size of an enclosure the thing to add is something solid, like MDF or a brick.  But in your case i would not add anything, I'd use it as is and adjust the port for a 30Hz tuning frequency.Support the12volt.com

DYohn wrote: something solid, like MDF or a brick.

lol, classic

Thanks for the help and I'll keep in mind that not only will a brick act as a good ballast but as a volume reducer as well They said loud music would damage my hearing,what do THEY know.What was that, did you say something :)