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View Full Version : Need some help figuring internal vloume, and port area



twistedmind
06-08-2008, 06:04 PM
http://www.aww-kittah-aww.com/up/files/1089/12345sadv.JPG
http://www.aww-kittah-aww.com/up/files/1089/awrgkah%3Bogrn4w5646.JPG

Second image is where my 2 amps r going to sit ( 18 " x 12" x 3" ) per rack, numbers are kind of hard to see

My Box design, assume External Dimensions shown, 3/4" MDF for build.

How much airspace is in there?
Port dimensions?

Id like to use 2 ports fireing towards roof, opposite ends of the box.

Thank you ahead of time for any help. Im trying to figure if I can fit 2 DD 3512's in my truck.

twistedmind
06-08-2008, 06:13 PM
I realize right now im going to have a issue with the top subs mounting depth, what I had in mind was to replace my stock bench seat with a pair of racing bucket seats and building the actual sub mounts forward another 6 inches ( between the seats, Ala Corvette style ) and useing fiberglass to get the correct mounting depth, this is just a basic do I have enough airspace available sketch.

Mr Cabinetry
06-08-2008, 06:49 PM
I'll help ya out here with this, but I want know what vehicle this enclosure is being designed to fit.

twistedmind
06-08-2008, 06:55 PM
I'll help ya out here with this, but I want know what vehicle this enclosure is being designed to fit.



2k regular cab f150 short bed

Mr Cabinetry
06-08-2008, 07:02 PM
2k regular cab f150 short bed


Enclosure total volume is 5.08 cu.ft

The two amp rack sections displace .68 cu.ft.

That leaves you with 4.39 cu.ft. before any additional displacements.

twistedmind
06-08-2008, 07:18 PM
Thank you so far my man, Now if you would be so kind as to do a touch more math for me.

Useing the following measurements

Port Area (sq in) 44

Port Length (inches) 16

per sub woofer, whats that going to leave my internal volume at, once again assuming 3/4 mdf for port build.

Also, could you give me a hole size to make? example 12 inches long x 3 inches wide x ?? deep = 44 sq in of port

thats off the DD sight, those are the only specs they list other than woofer displacment, and box volume


the sight recommends 2.5 cubes per driver

the subs displace .336 each

dannyz122001
06-08-2008, 07:24 PM
^^^ x2

twistedmind
06-08-2008, 07:25 PM
FYI since you do this for a living this box as is right now will fit behind the stock bench seat

dannyz122001
06-08-2008, 07:26 PM
well... if the total interior volume is just about 4.4 cubes before any displacements, thats about 2.2 cubes per sub w/o port disp. and sub disp. so i dont think your gonna get your 2.5 cubes per sub

dannyz122001
06-08-2008, 07:27 PM
well, thats also depending on how far out the top sub will extend with the FG.

twistedmind
06-08-2008, 07:32 PM
well... if the total interior volume is just about 4.4 cubes before any displacements, thats about 2.2 cubes per sub w/o port disp. and sub disp. so i dont think your gonna get your 2.5 cubes per sub



im going to do some extensive fiberglassing where the subs are, its going to extend out from the main box. im just trying to figure out how far out it has to go before I hit 5 cubes after ports.




so example, my racing seats are 23" wide at the widest point x 2 so 46" of seat that leaves me 17" between the seats to expand towards the dash to make up some airspace.

Mr Cabinetry
06-08-2008, 07:34 PM
Thank you so far my man, Now if you would be so kind as to do a touch more math for me.

Useing the following measurements

Port Area (sq in) 44

Port Length (inches) 16

per sub woofer, whats that going to leave my internal volume at, once again assuming 3/4 mdf for port build.

Also, could you give me a hole size to make? example 12 inches long x 3 inches wide x ?? deep = 44 sq in of port

thats off the DD sight, those are the only specs they list other than woofer displacment, and box volume


the sight recommends 2.5 cubes per driver

the subs displace .336 each

Give me a few, I'll have answer for ya.

Mr Cabinetry
06-08-2008, 07:48 PM
Port Size as follows - I. D. Size - 2.8750" x 15.3750" x 15.25" = .54 cu.ft.

That is also accounting for 3/4" MDF and the reason it's 15.25" length and not 16" is the 3/4" thickness of the top MDF is not part of the displacement.

So, to recap:

Enclosure total volume is 5.08 cu.ft

The two amp rack sections displace .68 cu.ft.

That leaves you with 4.39 cu.ft. before any additional displacements.

Subtract for slot port & walls( 3/4 ) = .54 cu.ft.

Volume now is 3.84 cu.ft.

twistedmind
06-08-2008, 07:52 PM
Port Size as follows - I. D. Size - 2.8750" x 15.3750" x 15.25" = .54 cu.ft.

That is also accounting for 3/4" MDF and the reason it's 15.25" length and not 16" is the 3/4" thickness of the top MDF is not part of the displacement.

So, to recap:

Enclosure total volume is 5.08 cu.ft

The two amp rack sections displace .68 cu.ft.

That leaves you with 4.39 cu.ft. before any additional displacements.

Subtract for slot port & walls( 3/4 ) = .54 cu.ft.

Volume now is 3.84 cu.ft.


did you just figure for one port, or 2 ports?

if 2 ports is the 2.875 x 15.375 x 15.25 for each port? Or did you combine them into one massive port?

twistedmind
06-08-2008, 07:53 PM
http://www.aww-kittah-aww.com/up/files/1089/095ugolsjbve3.JPG

a real quick rendering of what my fiberglassing will do minus the sharp edges

so just this little minor addition adds over 2 cubes to the enclosure.

Mr Cabinetry
06-08-2008, 08:04 PM
did you just figure for one port, or 2 ports?

if 2 ports is the 2.875 x 15.375 x 15.25 for each port? Or did you combine them into one massive port?

That is one port per sub, but I didn't account for the second port displacement, my mistake. I didn't read the whole thing.

Hold up till I re-check all the info.

Twisted, you got aim???

Mr Cabinetry
06-08-2008, 08:18 PM
Twisted,

I didn't account for the second port as for displacement.

You will need 2 Slot ports of the same size as mentioned.

the finally volume left to work with is 3.32 cu.ft.

Sorry for the mistake, better to catch if now than later.

twistedmind
06-08-2008, 08:19 PM
I have yahoo messenger silver85327

Mr Cabinetry
06-08-2008, 08:24 PM
I have yahoo messenger silver85327

I posted up the correct info.

Also, your plan is going to have to change given there are two ports, NOT ONE Port.

The extension that comes out between the seats need to be 11.5" x 16.5" x the height.

If ya want, I can render the entire enclosure as it would appear, mdf material, ports and amp recesses.

Mr Cabinetry
06-08-2008, 09:11 PM
Here ya go:

http://i29.photobucket.com/albums/c251/MrCabinetry/Z-Customer%20Bin/2dd3512prtd-Detail.jpg


http://i29.photobucket.com/albums/c251/MrCabinetry/Z-Customer%20Bin/2dd3512prtd-thruview.jpg

twistedmind
06-08-2008, 10:35 PM
http://www.aww-kittah-aww.com/up/files/1089/aesrhurvnaerbv4.JPG

heres what I came up with

twistedmind
06-08-2008, 10:39 PM
Question, do you figure 5 cubes before or after sub displacment? Im assumin after, did you take into account sub displacment Mr cabinetry?

Mr Cabinetry
06-08-2008, 11:39 PM
Question, do you figure 5 cubes before or after sub displacment? Im assumin after, did you take into account sub displacment Mr cabinetry?

Yup, I took all displacements into account for the design I posted.

In your design, you cannot put the amp where you have them because the depth of the amp recess is going to slam into/beyond the slot ports what you have them.

That's why I put the amp recess locations outboard with the slot ports centered, that's the only way everything is going to fit within the design.

Heres a side thru profile that shows what I am talking about:

http://i29.photobucket.com/albums/c251/MrCabinetry/sideprofile-thruview.jpg

twistedmind
06-09-2008, 12:09 AM
http://www.aww-kittah-aww.com/up/files/1089/Box%20Final%20Xray.JPG http://www.aww-kittah-aww.com/up/files/1089/Box%20Final%20solid.JPG

here are my final 2 designs, I reduced the amp rack to 2.5" deep and figured on 1/2" MDF for the ports to get them to clear each other.

However yours works useing completly 3/4 mdf so I may use it.


Question for you, if I decide to use your design, do I have permission? And If so how much for a set of prints, Im assuming you can print them from your program it appears to be better than mine.

and what did you end up with for total internal volume after mdf, ports, and racks, and subs in your design?

I need 5 cubic feet after displacment for this to work

Mr Cabinetry
06-09-2008, 12:22 AM
Hey man, the design is yours, not mine, I just helped ya with the finer points of working out all the details of it.

Besides, all I was really interested in was the vehicle it was being designed for and it can be modified to fit vehicles of similar floor pan detail.

I just like hacking on working out the more complicated designs and making it all come together.

I got all over 5 cf, more like 5.10 cu.ft., that little overage ain't going to hurt it one bit.