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
What more info would you need to help me build this box? Which sub specs specifically? I would love to learn and read up all about how to calculate it myself, but i have to have the box built by Friday March 4th and have it installed in a customers car, by 6pm that day.
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
I've been editing....check to see if there's more info. The two I mentioned. Once you get used to either one they're pretty quick to get results from....but not something you'll do in a couple of days. I'm talking about programs you can use on your own computer without having to pay, because they're free. If you want to pay for one, step it up a notch to LspCAD which a lot of the professional speaker designers use. It takes more things into consideration if you are building for competition, but I haven't looked at it....just heard about it.
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:
https://www.linearteam.dk/default.aspx?pageid=winisdpro
https://home20.inet.tele.dk/kou/ubmodel.html
https://www.libinst.com/LspCAD.htm
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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.
I just looked at your original post again....if you are limited to that space for the box, so that you end up with about 2 cu ft air space, it will still work for a sealed box. The low end will just drop off a little steeper, but it'll still be good. The Q goes up some but it's still below .8 which would be alright.
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.