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krazeeboy
09-02-2005, 06:14 AM
well i kinda cut 2 inches too short on the width of my slot ported box.

the box made by ported accelerator was 20"w, 15"h, 21.5"d and net volume of 2.0 tuned to 35hz. now its 18" in width and the i cut down the length on the slot port also 2" to keep an opening of 4" inside the box for the port. i know this will change the net volume a little but what about the frequency?

this was my original
http://img374.imageshack.us/img374/7094/boxorig3oz.th.jpg (http://img374.imageshack.us/my.php?image=boxorig3oz.jpg)

this is whats happened
http://img368.imageshack.us/img368/1058/boxcurr4ed.th.jpg (http://img368.imageshack.us/my.php?image=boxcurr4ed.jpg)

anyone got any ideas if thats ok or some major changes to the frequency has been made??

krazeeboy
09-02-2005, 05:22 PM
can anyone help me?

tRiGgEr
09-02-2005, 05:27 PM
If that 30.25 is the actual length of the port, your final box is 1.81ft^3 tuned to 37hz. 33.75 square inches of port surface area.

That is before speaker displacment...

krazeeboy
09-02-2005, 05:35 PM
ic thanks. but isnt a net volume of 2.0 after speaker displacement? my speaker displacement is .071 cubic feet. what will my final cubic feet be and frequency? also if i cut down the port length, how can the port area be the same?

PhatTonyDeMarco
09-02-2005, 05:41 PM
ic thanks. but isnt a net volume of 2.0 after speaker displacement? my speaker displacement is .071 cubic feet. what will my final cubic feet be and frequency? also if i cut down the port length, how can the port area be the same?


The net volume is 1.81 cubes, according to trigger. So after your speaker displacement (.071 cubes), the box will be 1.739 cubes.

What kind of sub is this? Seems like .071 is rather small..

krazeeboy
09-02-2005, 06:00 PM
its for alpine type R 12". i thought the manual was wrong too but thats what it said..so will 37-38 hertz be bad for daily driving? i lsten to mostly rap and hop hop and rnb.

tRiGgEr
09-03-2005, 12:24 PM
its for alpine type R 12". i thought the manual was wrong too but thats what it said..so will 37-38 hertz be bad for daily driving? i lsten to mostly rap and hop hop and rnb.


It will be fine on that type of music. The port surface area is determined by the Height and Width of your port not the Length. So it remained the same. You have to add port and speaker displacment to find the net volume. You can't build a 2ft^3 box with a 1ft^3 port and say it is still 2 cubic feet. It would be a 1ft^3 box.

Hope that helps

krazeeboy
09-03-2005, 09:49 PM
yes i know that. but on the port calculator it says desired net volume so shouldnt that mean it will calculate everything (speaker displacement, port disp) and give me a 2.0 net volume after speaker and port displacement?

tRiGgEr
09-03-2005, 10:01 PM
No. What are you using? Not even win ISD will do that.

krazeeboy
09-04-2005, 11:17 PM
http://www.accelerator-pedal.com/ported-box.asp

it says net box volume? iono

PhatTonyDeMarco
09-04-2005, 11:18 PM
http://www.accelerator-pedal.com/ported-box.asp

it says net box volume? iono



NET volume is total box volume, without anything deducted, (port and speaker displacement.)

tRiGgEr
09-04-2005, 11:47 PM
http://www.accelerator-pedal.com/ported-box.asp

it says net box volume? iono

Those types of calculators are basic. They require you to know how to account for displacment. And are not programmed to do everything for you.

krazeeboy
09-05-2005, 01:27 AM
ahhh i see it now after doing some calculations to make sure, so i will have 1.739 cu feet tuned to 38.6 hrtz for the type r and that is ok for rap rnb and hip hop right? thanks guys

krazeeboy
09-05-2005, 03:04 AM
hey trigger wait how did you arrive at 1.81cu ft of volume before displacements again?

correct me if im wrong which i probably am but considering my 18", 15", 21.5 external measurements. if i subtract the .75 mdf wood from the sides and the inside and get internal measurements of 15.75",13.5",19.25" by subtracting 0.75 x 3 for the width and depth, and 0.75 x 2 for the height i get an internal volume of 2.36 cu ft before displacement by

15.75x13.5x19.25 = 4093.03
take that divide by 1728
and you get 2.36 of cubic feet before port and speaker displacement
i dont know if im right but i just thought of it lol
i hope i am right though because that would mean i get around 33 hertz tuning frequency :cool:
feel free to burst my bubble..lol

krazeeboy
09-05-2005, 03:17 AM
scratch that im wrong haha...thread closed

GTonDubs
09-05-2005, 11:17 PM
its for alpine type R 12". i thought the manual was wrong too but thats what it said..so will 37-38 hertz be bad for daily driving? i lsten to mostly rap and hop hop and rnb.

if you tune it up to 38 hz plan on it bottoming out when it hits a low tone in a rap song
36hz or under will keep the lows beating real good

chubby
09-05-2005, 11:18 PM
if you tune it up to 38 hz plan on it bottoming out when it hits a low tone in a rap song
36hz or under will keep the lows beating real good

most rap is in the 40-50 range.