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View Full Version : how do you figure up the port area

king ranch
01-11-2008, 06:18 PM
anyone kno the formula for that
the port area and the cu space it takes up
thanks

ultimate157
01-11-2008, 06:19 PM
square port: length x width

round port: Pi * r^2

Multiply either by the length (make sure to account for wood thickness) to get volume displaced.

tommyk90
01-11-2008, 06:20 PM
square port: length x width

round port: Pi * r^2

Multiply either by the length (make sure to account for wood thickness) to get volume displaced.

And if he's calculating his box size in cubic feet, take those numbers and divide them by 1728. :)

king ranch
01-11-2008, 06:24 PM
no i already have the box voulme i am wondering how to determine how much area and cu ft of space the port will take up its a slot port

its 4inches high 24.5long and 15.5wide

what would be the area for that and the cu ft it takes up

ultimate157
01-11-2008, 06:34 PM
Edit: Which measurement is to the inner port wall? Will make a difference in volume.

king ranch
01-11-2008, 06:46 PM
http://i7.photobucket.com/albums/y290/mobeious/Untitled-2.jpg

http://i7.photobucket.com/albums/y290/mobeious/Untitle1d.jpg[/QUOTE]

15.5 wide 24.5long with the 2inch lip that sticks up and the port is 4inches high

king ranch
01-11-2008, 06:47 PM
those are inner measurements

ultimate157
01-11-2008, 06:57 PM
Including the wood thickness, the port displaces 1.04 cubes. (Assuming 0.75" MDF)

Has a port area of 62 in^2.

king ranch
01-11-2008, 07:01 PM
ok if you could work out the math for me or jut give me the formulas so i kno for in the future

by the way thats a 33hz tune and will taht work for 2 12's l7's

the entire box internal is 24.5 deep 29.5 tall and 15.5 wide
so each sub should have right at 2.6 net

king ranch
01-11-2008, 07:12 PM
bump

king ranch
01-11-2008, 07:27 PM
formula for figurging out area for port plzzzzz
thanks

tommyk90
01-11-2008, 07:38 PM
formula for figurging out area for port plzzzzz
thanks

It was already given to you.

Length x height=port area.

king ranch
01-11-2008, 07:40 PM
sorry so is 62 enough for the 2 12's l7's with a new of 5.2 after displacment for everything

i heard 80-87 is proper area for port is that true

tommyk90
01-11-2008, 07:41 PM
sorry so is 62 enough for the 2 12's l7's with a new of 5.2 after displacment for everything

i heard 80-87 is proper area for port is that true

62 square inches is plenty.

king ranch
01-11-2008, 07:44 PM
ok thanks and also would that be louder or would 3 4inch aeros at 16.02inches be louder both same tunning subs and power and same net for subs

Lakota
01-11-2008, 11:32 PM

ultimate157
01-11-2008, 11:38 PM
It was already given to you.

Length x height=port area.
Width x Height :)

ultimate157
01-11-2008, 11:39 PM
You could always take the integral from 0 to width under the height to get the port area as well.

BuckyBoy
01-11-2008, 11:40 PM
ok thanks and also would that be louder or would 3 4inch aeros at 16.02inches be louder both same tunning subs and power and same net for subs
Holy ****. You have asked the same questions about 55 times in the past week. Everything has been answered numerous times for you. I have made 15 designs and after each one you decide "it won't be loud enough because someone on f150 forums told me so"
Although it may seem like it sometimes, this **** isn't rocket science. When we tell you something will sound good, it will sound good.

Lakota
01-12-2008, 12:59 AM
You could always take the integral from 0 to width under the height to get the port area as well.

True. This is how I find the area of circles and squares.
http://img.photobucket.com/albums/v231/Lakota/Project4.jpg

tommyk90
01-12-2008, 05:29 AM
Width x Height :)

oopsie.

Trying to repeat myself over and over ftl.

ultimate157
01-12-2008, 08:49 AM
oopsie.

Trying to repeat myself over and over ftl.

Heh.

Quick question: When determining port length and area displaced, I saw some talk about end-of-port correction (When talking about real world application, harmonics)

Does the effect of the opening of the port on the sound waves need to be taken into account when determining proper port length and width?

tommyk90
01-12-2008, 01:43 PM
Heh.

Quick question: When determining port length and area displaced, I saw some talk about end-of-port correction (When talking about real world application, harmonics)

Does the effect of the opening of the port on the sound waves need to be taken into account when determining proper port length and width?

I've never, ever calculated for end correction when I've made any of my boxes, slot port or aeroport, if that says anything to you.

When doing simple calculations in winISD i've only seen a variation of 1-2 hz in the tuning frequency with end correction factored in, too little for concern IMO.

PV Audio
01-12-2008, 01:46 PM
You could always take the integral from 0 to width under the height to get the port area as well.Would that even be a function though? I guess 0-3 if f(x)=port height, but I dunno. I'ma try that out though :D

PV Audio
01-12-2008, 01:48 PM
Heh.

Quick question: When determining port length and area displaced, I saw some talk about end-of-port correction (When talking about real world application, harmonics)

Does the effect of the opening of the port on the sound waves need to be taken into account when determining proper port length and width?No, not really. End correction for most enclosures comes out to be around 1hz difference anyway, and for a large enclosure, it makes next to no difference.

ultimate157
01-12-2008, 01:56 PM
Would that even be a function though? I guess 0-3 if f(x)=port height, but I dunno. I'ma try that out though :D

it would just be a definite integral of a constant. Works out to be 15.5x from 0 to 4. 15.5(4)-15.5(0) = 62 in^2 :)

Lakota
01-12-2008, 09:47 PM
Just use double integration and forget the function. You all are making it difficult.

PV Audio
01-13-2008, 06:12 PM
****, let's laplace this **** while we're at it! :D

Lakota
01-13-2008, 11:16 PM
****, let's laplace this **** while we're at it! :D

I try to leave my memories of Calc 2 behind me. I hated that class.