Box for Type-R 15

Could someone with a box program please tell me what my port size should be.  The box i plan on makeing is 23" length x 18"height x13"depth , = 2.36cubic feet.  Im asumeing the port size will have to be subtracted from the total box volume?  I would like to make a slot port too.  Tuneing around 25hz, im trying to get the best all around sound , with a good amount of sq.

Thank you

Dude, you seriously need to spend some time getting familiar with one or two software modeling programs to do this stuff.  Look up WinISD Pro alpha and Unibox.  WinISD works as a Windows-based program;  Unibox is an Excel program.

I did a quick look at WinISD for this, used the sparse bit of parameter info on the Alpine site....this is for the SWR 1541D (dual 4 ohm, wired in paralllel, total 2 ohm impedance).  You want 25 Hz tuning in a vented box.  This sub calls for sealed.  It has an EBP of 48 which is well into the sealed catagory.  3.0 ft^3 box, very good low extension (Fsc is 36 Hz)........best for SQ with this sub.

For vented, if you want to go that route, keep the tuning freq. at about 20 Hz for flattest response because you'll get an awful peak if you tune to 25Hz.  You'll get deeper bass extension this way over the sealed box, but the freqs will be a bit lower than most music material.  The slotted vent on this box will be rather large, and I don't know what space you have to work with in your design....but keep the slot opening no smaller than 3" X 8" with a length of 36 1/4".  You'll be building the slotted port to extend along more than one length of the box.  Calculate the port volume including walls by using the rectangle calculator on this site and add the volume to the total.  Also add the sub displacement.

You want total net volume for this vented box to be 4 ft^3.  Hope it's a damn big car.

If you want to tune to 25 Hz, the peak is 2 db which I guess is really not that bad, just looks bad on a graph.  If you do, you would drop the box net volume down to 3.0 ft^3 and the slotted port will remain the same area opening size but be a bit shorter at 30 1/4".  I'd probably go this route because the box will be smaller and more manageable.

humm, guess this isn't going to work out how i planned.  I guess whell have to go sealed.  Thanks alot!   Which is one of the best box programs to have? im trying to convince the boss to invest in one.

Thanks alot stevdart

The 3.0 ft box at 25 Hz would be a louder setup than the sealed by up to 6 db at 30 Hz, 4 db at 40 Hz.  Here are those links:

http://www.linearteam.dk/default.aspx?pageid=winisdpro

http://home20.inet.tele.dk/kou/ubmodel.html

http://www.libinst.com/LspCAD.htm

I built up a 3 cu ft box for it, and tested it today, very impressive.  Its rare we sell 15's so i haven't really heard them until today, the sound it definately tighter that expected.

Thank you very much for your help.  

Now im really interested to read and learn as much as i can about porting.

Good!  Glad to be able to help.  Here are a few links I have saved....most have something to do with building a vented enclosure.  Pop them into your favorites folder and go through them sometime....some will prove invaluable over and over.

http://www.installdoctor.com/home.html