# I JUST LEARNED A NEW WAY TO MAKE SUBWOOFER BOXES



## ROAD_DOG (Jan 22, 2007)

Probably nothing new to most of you but for those who dont know how to make a subwoofer box with the correct internal volume this is how I learned from a friend who has been doing car audio since he was like 15 years old.

Ok first off is deciding which subs you want to put in your car I am choosing to install a set of Kicker CompVR 12's with an Enclosure of 1cu.ft with a net displacement of 122.1 per woofer.

When you measure your trunk you have the task of deciding how much trunk space you willing to sacrifice for your sub box my measurements are as follows

15"H X 32"W 

Reason why I only measured H X W is because after you do the math the depth of the box comes out of the final equation.

Now I subtracted 1.5 from the external dimensions because I will be using 3/4in MDF board.

My internal dimensions are:
13.5"H X 30.5"W 

Multiply the internal dimensions to get your internal cu.in
13.5"H X 30.5"W = 411.75cu.in

Convert 2cu.ft to cu.in each sub has a recommened enclosure of 1cu.ft
2cu.ft X 1728 = 3456cu.in

Now add subwoofer displacement to 3456cu.in to get your new cu.in keep in mind that each sub is 122.1 displacement
3456cu.in + 244.2 = 3700.2cu.in

Now divide 3700.2cu.in by 411.75 (411.75cu.in is the equation from multiplying 13.5"H X 30.5"W)
3700.2cu.in / 411.75 = 8.98 <--------------round off to 9.00

Add .25 to 9.00 to get you internal depth dimension this is because the displacement of the center divider
9.0 + .25 = 9.25 inches is the final measurement for the internal depth of the box 

So then my dimensions are as follows

Internal dimensions are
13.5H" X 30.5"W X 9.25"D

External dimensions are 
15"H X 32"W X 10.75"D

So to ensure that I will have the proper internal volume recommended ill just multiply my internal dimensions then subtract this total displacement of the subs then divide by 1728

13.5"H X 30.5"W X 9.25"D = 3808.6875cu.in

3808.6875cu.in - 244.2 (displacement of subs)= 3564.4875cu.in

3564.4875cu.in / 1728 = 2.06cu.ft <---------- right on the money

So now with confidence I can now build my box hope this helps every one I know this might not be new to some one but some one who doesnt know how to work out the math this should help also reason why I measured only height and width is that when you start doing the math the final measurement comes out this way it eliminates the guess work of having to re-think the measurements because you made it to small or to big.


----------



## bigdoggfromaz (Aug 28, 2008)

whats all this munbo jumbo nah just kidding good looking out could have used that 2 weeks ago when i was looking thru the internets on how to do what you just explained i couldnt find it and i wasn/t confident enough to build my own so i had someone else build it :biggrin: but i still havent seen the box yet  but i knew this would happen and the good thing is that i know he will do a good job :thumbsup:


----------



## ROAD_DOG (Jan 22, 2007)

> _Originally posted by bigdoggfromaz_@Apr 8 2010, 11:51 PM~17141718
> *whats all this munbo jumbo nah just kidding good looking out could have used that 2 weeks ago when i was looking thru the internets on how to do what you just explained i couldnt find it and i wasn/t confident enough to build my own so i had someone else build it :biggrin:  but i still havent seen the box yet   but i knew this would happen and the good thing is that i know he will do a good job  :thumbsup:
> *


glad to help out i just learned this shit its helpful information i did the same formula on some 15" kicker compvr just different measurements and every thing worked out even with other subwoofer brands this is only the beginning ill later learn how to properly do the ported enclosures but the way i described every thing you cant go wrong


----------



## draarong2004 (Feb 20, 2005)

you know when you mulitply just height times width your getting SQUARE INCHES correct? your only measureing a 2 dimensional object.....

i'd like to know who told you to go by this means, never seen/nore heard of this one before. And its an awful lot of math when you could get your heightxwidth and have a calculator handy and keep playing with the depth number, multiplying all of them and dividing by 1728(which is 12x12x12 or 1 cubic foot). no need to add all that extra math into the equation.


----------



## draarong2004 (Feb 20, 2005)

for future reference, remember this place for anything you'll need help with
http://www.the12volt.com/caraudio/boxcalcs.asp
easy to use box calculators


----------



## ROAD_DOG (Jan 22, 2007)

> _Originally posted by draarong2004_@Apr 9 2010, 09:17 AM~17143842
> *you know when you mulitply just height times width your getting SQUARE INCHES correct? your only measureing a 2 dimensional object.....
> 
> i'd like to know who told you to go by this means, never seen/nore heard of this one before.  And its an awful lot of math when you could get your heightxwidth and have a calculator handy and keep playing with the depth number, multiplying all of them and dividing by 1728(which is 12x12x12 or 1 cubic foot).  no need to add all that extra math into the equation.
> *


I figured i post this for others that need a little help it might seem like alot of math but in reality its only like 4 equations you just got to work out and it hasn't failed my friend i just suggested in the end to ensure if dimensons are correct to just do a little extra math.

But for someone who is starting out building boxes this can be some helpful information a more experienced builder probably wont need to do it this way its easy for me this way that way i dont need to be guess the depth if i make it to big or to small.


----------



## ROAD_DOG (Jan 22, 2007)

> _Originally posted by draarong2004_@Apr 9 2010, 09:20 AM~17143864
> *for future reference, remember this place for anything you'll need help with
> http://www.the12volt.com/caraudio/boxcalcs.asp
> easy to use box calculators
> *


yep these are pretty helpful calculators i refer to these as well when i worked out equations.


----------



## dken (Nov 11, 2005)

i like this one the best. its stupid proof!
http://www.reaudio.com/speaker_box/LPort_Box_Calc.html


----------



## ROAD_DOG (Jan 22, 2007)

> _Originally posted by dken_@Apr 11 2010, 01:55 PM~17160445
> *i like this one the best. its stupid proof!
> http://www.reaudio.com/speaker_box/LPort_Box_Calc.html
> *


ok please explain on how i can use this to make a ported box this relatively new to me at this moment i only understand the math to do sealed boxes but ported i need to get more info im planing to use the kicker compvr 12's sealed i would like a ported enclosure but not to technical on ported enclosure or how to properly build them please explain how i can use 2 subs in this one L ported enclosure this is just giving me for 1 sub but ill be running 2 thanks in advance


----------



## Blazerbump03 (Apr 20, 2006)

lol i like the fact that no matter how hard you sir, tried to better the mathematical horizon of all these members, they still only point you to a calculator, i use this same method when i build enclosures, its basically the same as finding the last angle of a triangle by using the 2 known numbers kind of thing, it will never fail you and isnt hard to remember, and makes you look THAT much cooler when your designing something for a customer .

You can also use the same formula to add port displacement beforehand to make sure that it 1, the box will fit into your car.. and 2 that the port will have enough room to fit in the enclosure.

Still, i appreciate the fact that at least you took the time to share this, you deserve a high five of epic proportions.


----------



## ROAD_DOG (Jan 22, 2007)

> _Originally posted by Blazerbump03_@Apr 11 2010, 08:14 PM~17163536
> *lol i like the fact that no matter how hard you sir, tried to better the mathematical horizon of all these members, they still only point you to a calculator, i use this same method when i build enclosures, its basically the same as finding the last angle of a triangle by using the 2 known numbers kind of thing, it will never fail you and isnt hard to remember, and makes you look THAT much cooler when your designing something for a customer .
> 
> You can also use the same formula to add port displacement beforehand to make sure that it  1, the box will fit into your car.. and 2 that the port will have enough room to fit in the enclosure.
> ...


 

so based on my equations if i was making a slot ported enclosure and the manual says 1.75cu.ft + port displacement i add 1.75 to the 1cu.ft the sub needs for a sealed enclosure and i have my ported enclosure did i get this right


----------



## Blazerbump03 (Apr 20, 2006)

You would take the 1.75 cf, add in the speakers displacement, and depending on what size port you use, once calculated using a program or a formula that i would never honestly be able to remember, then add the displacement of the port in, so the total area now has enough space for everything.

so again..

Desired internal airspace + Speaker displacement + Port displacement

Hope that makes it a little more clear.


----------



## Airborne (Oct 23, 2005)

> _Originally posted by Blazerbump03_@Apr 12 2010, 06:48 AM~17166111
> *You would take the 1.75 cf, add in the speakers displacement, and depending on what size port you use, once calculated using a program or a formula that i would never honestly be able to remember, then add the displacement of the port in, so the total area now has enough space for everything.
> 
> so again..
> ...


yep, people wonder why their box that is "4.2 cubes @ 30hz" doesn't get as low as they thought. Then you do a little math and tell them that the port displacement wasn't factored in to the internal volume they almost cry.

Not everyone knows about subtracting port and sub displacement. Add to that 2x4's for bracing and 45's in every corner and some people end up WAY the fuck off on their volume.


----------



## Blazerbump03 (Apr 20, 2006)

My fellow members, now adding countless mumbo jumbo to figure out a precise tuned port is no longer a problem, no longer do you have to factor in your displacement or worry about the size whatso ever, with new developments in port technology i am now selling ghettoports for only 25$ shipped anywhere in the US!










Paypal accepted, pm for any orders


----------



## southside64 (Jul 4, 2006)




----------



## Blazerbump03 (Apr 20, 2006)

> _Originally posted by southside64_@Apr 12 2010, 10:51 PM~17173663
> *
> *


Theres about 64 ounces of sarcasm for you to drink in before you realize its just a joke :biggrin:


----------



## ROAD_DOG (Jan 22, 2007)

> _Originally posted by Blazerbump03_@Apr 12 2010, 03:48 AM~17166111
> *You would take the 1.75 cf, add in the speakers displacement, and depending on what size port you use, once calculated using a program or a formula that i would never honestly be able to remember, then add the displacement of the port in, so the total area now has enough space for everything.
> 
> so again..
> ...


well the smallest enclosure possible in air space i dont wanna make it to big only to find that i cant fit it inside my trunk the math i had worked out earlier is for a sealed enclosure that i know would fit i know if going ported i would need to make it bigger so i am gonna try to work out the math how you stated for making a ported box to see if you can help me correct anything i did wrong thanks for the info bro :thumbsup:


----------



## brian84corvette (Nov 22, 2009)

I use the rockford fosgate woofer box calculator. super eazy good/ acurate

http://www.rockfordfosgate.com/rftech/box_advisor.asp

been using it forever now. always acurate


----------



## djbizz1 (Nov 26, 2005)




----------



## ROAD_DOG (Jan 22, 2007)

> _Originally posted by djbizz1_@Mar 26 2011, 07:03 PM~20188465
> *
> 
> 
> ...


 :uh:


----------



## JOE(CAPRICE)68 (Jul 5, 2008)

> _Originally posted by Blazerbump03_@Apr 12 2010, 07:47 PM~17173607
> *My fellow members, now adding countless mumbo jumbo to figure out a precise tuned port is no longer a problem, no longer do you have to factor in your displacement or worry about the size whatso ever, with new developments in port technology i am now selling ghettoports for only 25$ shipped anywhere in the US!
> 
> 
> ...


 :biggrin:


----------



## ~nip/tuck~ (Mar 11, 2011)




----------

