Box for two DD 1508's - Got questions..

[loudmofo 5,000+ posts]

like this '

 

[westman995 10+ year member]

Ya i understood what you meant to make it that way, i was just wondering if it would work fine like that. I just like the look of the subs on one side. So i should put the subs in center like your pic, or is it ok to do them both to the side, but put the port right behind the subs like yours?

And are you saying to make the port the whole length of the box?

 

[loudmofo 5,000+ posts]

the subs should be close together for beter spl the port can be ethier way just not like on top like that pic

 

[westman995 10+ year member]

Should the port be the full length of the box like your pic or should it be not as long? Either way, the port as long as the box looks kinda cool.

 

[westman995 10+ year member]

I dont think its going to look quite so long when its drawn to specs tho, the drawing makes it look a little long.

http://i242.photobucket.com/albums/ff177/westman995/*****%20Am/*****%20Am%20Stereo%20System%20Install/Untitled5.jpg

 

[westman995 10+ year member]

Well according to the slot port calculator on the12volt.com, i put my rough estimates in of the box to get about 1.8 cubes with the box being 25" long, 17" high, and 10" deep. But that is before displacement of the subs and the port. Not looking too good, I havent measured but i dont think i want to go any higher on the height of the box or the plexi wouldnt look or do much good i dont think..

And if i do a 24 inch long by 1 inch wide port on the rear, tuned to 37 (just a random number to try( the port needs to be 22 inches long.. So im not really sure how the hell im going to pull this off, unless i build the box like my original design which is going to **** do to all that extra cutting and shit that im not really that great at.

EDIT: Ok this is not looking real good. Even by doing my original design, i dont seem to be able to get very much volume out of it. The thing is i was at first measure 20 inches from bottom up total, but i just measured and realized i only have 15" from bottom to top to work with. So even with the top part being bigger, it looks like i only get about 1.8 cubes not even counting a port.. The port is going to take up quite a bit of volume, am i right?

 

[loudmofo 5,000+ posts]

you will need to bend the port to make it work look up port bending

 

[westman995 10+ year member]

But even besides the fact of the port, how is the less volume going to affect it? I dont want to go through all the trouble of building this box custom to the car, and then turn out to not be big enough and not be as loud as it can get.

 

[westman995 10+ year member]

Ok so this is drawn much more closely to spec as i measured it on sketchup, its not dead on but real close. Now, is there a box calculator out there to find the volume of this shape? I cannot find anything. Or how would i do it on a regular calculator? The only thing i can think of is do the top part and bottom part seperate and add them, but it wont be exact volume then.

Specs are 25 wide by 10 deep on bottom, 15 from top to bottom, 40 wide on top piece, the middle pieces that stick out one side is 5 and other is 10.. I didnt know how to write on the pics so i had to type them out.

Where i the ideal location of the subs in a box of this shape? Im afraid of the shape being a problem. I dont really know, its just something i want to figure out before its built.

http://i242.photobucket.com/albums/ff177/westman995/*****%20Am/*****%20Am%20Stereo%20System%20Install/1508box2.jpg

 

[westman995 10+ year member]

Would you suggest this design?

How about have the port like pictured, and have the subs right next to each other on one side of the box? Im just afraid of the shape something may not work right haha..

http://i242.photobucket.com/albums/ff177/westman995/*****%20Am/*****%20Am%20Stereo%20System%20Install/1508box5.jpg

Ok so if i make the port 18x1" it asks me to make it 14.8" so it would make it easier to make the port.. Does the width or height of the port really matter if its tuned correctly to what its saying? Or is the wider port going to be better?

 

[westman995 10+ year member]

Ok so i threw the subs in a small slot ported box, a real piece of shit haha.. I tuned the port to 40hz, and wow i am very surprised already. And im only pushing 125 rms to each sub.. Cant wait to get them in a real box, and some real power to throw at them.

Anyways, knowing that box theyre in now is too small and theyre already somewhat loud, i am just going to build the box to whatever size looks best in there, in the end after port displacment i think it should be a nice size and do pretty well. Only time will tell tho to see how it really sounds.

Now, one of my main questions i need to know is.. Does the height or width of the port matter as long as i make it the right length to the hz im tuning it to?? I mean do i really gotta build the port from one side the other? Seems really long.

So, can i get away with doing the port like the last pic i posted?

 

[Fuknmovin 10+ year member]

You need to have the proper port area for your subs, I am not familiar with DD's specs but typically you can take the volume of the box after displacements and mulitply it by 16 to get the desired port area for good output. take the height times the width to get total port area. You need this AND the right length to get it performing its best. You have nice subs they deserve the right box, do your homework and it will turn out nice!

 

[westman995 10+ year member]

The DD site says 15 sq in. port area, and 19 inches long. Do i really have to go with 19" long, or do i do the length according to my box?

So i would want to get a total of 30 sq in port area for the two subs, or not?

EDIT: Ok i came across this on the DD site

1.50^ft (2) 8" or (1) 10" 24.0 sq" vent x 22" long

1.75^ft (2) 8" or (1) 12" 28.0 sq" vent x 21.5" long

2.00^ft (2) 8" or (1) 12" 32.0 sq" vent x 21" long

So, im prolly going to be doing the 2x8" witha about 1.5 cubes after displacement.

Im also PMing another member thats helping me out, he told me it needed to be 22" long, which i did not know what that meant at first. But now i understand better. I never knew about the having to have so much port area. I just thought it was tune it to whatever and that was it.

So lets say i got 1.5 cubes after displacement. And the port is 22" long, how do i find out how deep and wide to make it to get the right port area?

EDIT 2: Ok once again this it not looking to great, seeing as how it says to use a 22" long port, i dono how in the hell i can fit that on my box with the way its shaped. I could try to do it in the middle of the top of the box, but the subs are going to be in the way. If i put the port on one side of the box, i cannot make the port real long due to the shape of the box?? And i dont see how bending the port in any way could help or be beneficial...?

 

[Fuknmovin 10+ year member]

just do the math, if you need 28sq" of vent then you need to play with it until you get what you need like this..14" wideX2" tall = 28" of port area, then make it as long as you need to to get the tuning you need, a website called (the12volt.com) has a calculator for the length...

 

[Fuknmovin 10+ year member]

Sometimes you will find a certain tuning frequency or box shape just flat can't be done, so you need to try something else. You can bend the port around the back of the box sometimes to help. Try messing with this calculator to learn more about how it works...

http://reaudio.com/speaker_box/LPort_Box_Calc.html