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View Full Version : DD1508 enclosure math.



got-one-eight
07-08-2009, 06:48 PM
I got a DD1508 I will be running soon. My box I think is a little on the big side and tuned kinda low. Could someone please help me check my math and how low should I port the DD1508... DD says 40hz even for an SQ tune? I may need to add some filler to the box to get the right cubic feet and of course will have to retune. Thx for any help!

http://i14.photobucket.com/albums/a308/badlilhemi/Boxmeasurements1.jpg

http://i14.photobucket.com/albums/a308/badlilhemi/Boxmeasurements2.jpg

http://i14.photobucket.com/albums/a308/badlilhemi/boxfinished2.jpg

thevic24
07-08-2009, 07:05 PM
how much power do you have to use and is the 1.19cuft before port and sub displacement?

imo, the 1508's sound really good in anywhere from .75-1cuft tuned to between 35 and 40 hz. i like mine tuned to about 37hz but imo i wouldnt tune any lower than 35hz.

http://i158.photobucket.com/albums/t82/thevic24/mn1.jpg

if your going to use the same box that you had the w7 in, you will have to enlarge the sub cut-out some.

got-one-eight
07-08-2009, 07:09 PM
Yeah.. my worries is goign to this sub and not liking it. Is one cubic foot before or after sub displacement? I have a JL 1000/1 but I will go easy on the sub and adjust my gains so im not killing it. I want more of an SQL setup if possible. I was thinking 36-38hz tune. I need help getting an exact calculation on my box so I can see if I need to add wood to the inside to get the size right. Hope it sounds good.. not sure if hte W7 will go back in after I enlarge the cutout some. If I remember right its before port and sub displacement... which is why I need help with the math above.. I did this box 4 or so years ago.

thevic24
07-08-2009, 07:20 PM
well the w7 imo is a better sounding sub but for me the 1508 dose just fine and it will take your 1k just fine. i have 3 1508's that i bought new and they all had to loosen up a bit to get right imo. for me it took a few hours of play time and they have turned out great.
your box should be fine. imo, tune it to 35ish and you should be happy with the sq and should have more output than the w7. dont jump to conclusions right away, give it some time to break in and afterwards dont be afraid to give it a good helping of that 1000/1 you have.
mine in the pic above is running on a mtx 81000d in a trunked car and is impressive for an 8.

after displacements you should be in the area of 1cuft so tune it for that.

got-one-eight
07-08-2009, 07:29 PM
So after sub and port displacement I should have about a cubic foot? How long of a 3" port should I run? I think I am tuned 33hz right now. I know the arrow port is a bit harder to measure.. If I remember right I cut the center pipe 5" shorter then the length I am aiming for and then pop the two flanged ends on.

thevic24
07-08-2009, 07:35 PM
to be honest, id try it just like it is and see how it sounds(let it break in first).

got-one-eight
07-08-2009, 07:45 PM
to be honest, id try it just like it is and see how it sounds(let it break in first).

My port is 14" long 3" aero port. Makes me wonder If I was off before on my math. I can order another aero port and just cut it to fit.. from my calculations (prob wrong) It should be ~ 10.5" for 35-36hz... I redid the math and after subwoofer displacement I got 1.155 cubic feet. I didn't do port displacement but used a website to calculate port length.. I assume it took in effect port displacment? ****.. means im more at like a 32hz tune right now.

thevic24
07-08-2009, 07:47 PM
its going to be so close that it shouldnt matter, its very hard to tell a 35hz tuning from a 38 hz tuning.

got-one-eight
07-08-2009, 07:51 PM
its going to be so close that it shouldnt matter, its very hard to tell a 35hz tuning from a 38 hz tuning.

Yeah.. at 32 now.. I figure ill cut the port to 10.5" should put me close and play around with both ports I have. I will probably pickup a couple aero ports and try different tunes. Im just worried my box is to large. I think I can feed it more power with a higher tune right? Any idea if the W7 will go back in after the DD1508 has been in there? Or do you think I wont want to throw the W7 back in? :) I can bottom out the W7 easily on the 500/1 I had.

thevic24
07-08-2009, 07:55 PM
the w7 wont fit after you cut the box and as far as power, a lower tune will allow you to play lower notes louder but with a higher tune the over all output will be louder for the most part.

iam suprised the w7 was bottoming out, you shure the amp wasnt clipping?

got-one-eight
07-08-2009, 07:59 PM
the w7 wont fit after you cut the box and as far as power, a lower tune will allow you to play lower notes louder but with a higher tune the over all output will be louder for the most part.

iam suprised the w7 was bottoming out, you shure the amp wasnt clipping?

It was a nasty sound and the sub was throwing pretty hard. It sounded like a mechanical noise (its 4 years old now). I hope the 1508 sounds good if I cant put the W7 back in........

got-one-eight
07-09-2009, 09:05 AM
Can someone help me with my math before I go cutting up the aero port?

sjobas
07-09-2009, 09:12 AM
fill it with dry sand, than you se how big it is if you use something to measure with

krainium
07-09-2009, 09:17 AM
I would try it like it is and if you dont like trim a little of the port. 1/2" is about 1 hz. If you still dont like keep trimming it. I wouldnt go any shorter than 9" though. Here is a port calculator for aero's you can play with the numbers to see how much of a difference it makes.
http://www.psp-inc.com/

got-one-eight
07-09-2009, 10:46 AM
I would try it like it is and if you dont like trim a little of the port. 1/2" is about 1 hz. If you still dont like keep trimming it. I wouldnt go any shorter than 9" though. Here is a port calculator for aero's you can play with the numbers to see how much of a difference it makes.
http://www.psp-inc.com/

Well according to my math and the length of my aero port im dead on the 33hz I was aiming for before. I have two aero ports coming.. ill cut one at 35hz and one at 38hz... then I will play with those three :) thx for the link!