[My T-line and halfa$$ explination for those who were asking about it.]

Just keep the power low and you'll be fine

How low is low?

[My T-line and halfa$$ explination for those who were asking about it.]

arent you supposed to have the speakers vertical, not horizontal? because the one closer to the port is "farther away" internally than the other one.

like side by side instead of front and back?

[My T-line and halfa$$ explination for those who were asking about it.]

arent you supposed to have the speakers vertical, not horizontal? because the one closer to the port is "farther away" internally than the other one.

That is correct,

Also the port length is not from wall it's from furthest edge of sub

Bu I like to use the centre of sub

Secondly 1 sub is going to unload more then the other due to firing down the port

And there's no port restriction to, normal you'll build you the wall with another 3/4 to assist is pressure differences, making it a more free flowing box

But all this in a perfict world, witch we are not

I don't think you'll notice it to much sq wish and I will still sound good

Just keep the power low and you'll be fine

1st TLine, Thanks for the input, I will keep that in mind if I build another down the road. What do you mean when you say port restriction?

[My T-line and halfa$$ explination for those who were asking about it.]

I swear i've seen that program before.. i could just never figure out how the hell to use it. can you lead me in the right direction?

I used Google Sketchup and cutlist.

[My T-line and halfa$$ explination for those who were asking about it.]

.75" Baltic Birch

Dry Fit:

Used a pocket hole jig on the port walls.

Used 13" pieces of wood to lock in the port dimensions.

45's in

Added Dowels and Painted the port.

Tested some bed liner spray paint. Works OK but I think i will go with roll on bed liner. Rounded over all my edges.

This is where I stand right now. Waiting on speaker wire before I finish painting.

[My T-line and halfa$$ explination for those who were asking about it.]

I don’t know much about much but this is how I do it. Hopefully I’m not too far off.

You can search the web and Find out the scientific explanations if you like. I like to do dumb it down a bit when I do it!

This helped me a lot and hopefully it will help out others as well.

Get the Specs of your sub off the internet if you do not have them handy

The tuning and port length is a simple math equation.

Divide 1130 by the FS of your sub divide that by 4 and then multiply it by 12.

Or:

1130 / FS / 4 * 12 = port length in inches.

Here is the math on a lot of common frequencies rounded to the nearest quarter inch:

20hz = 169.5”

22hz = 154”

24hz = 141.25”

26hz = 130.5”

28hz = 121”

30hz = 113”

32hz = 106”

33hz = 102.75”

34hz = 99.75”

35hz = 97”

36hz = 94.25”

37hz = 91.5”

38hz = 89.25”

39hz = 87”

40hz = 84.75”

You should choose Tuning right around the FS of your sub.

PORT AREA:

For Port area you can measure and do a bunch of math. Or you could us this handy Cone area of a subwoofer Chart that someone on here pointed me to!

Figure out what you are working with. Rounding the numbers makes the dimensions easier to work with later on.

Two 12" = 226.19, I round to 200

So Two 12” subs needs an internal port of 10”x20” or 12.5”x16” or 8”x25”

can be whatever you want as long as the length times width equals 200 and the port has enough depth for the sub to mount.

If you are firing subs and port back measure your max box height and subtract 1.5”

if you are firing subs and port up measure your max box depth and subtract 1.5”

that number you end up with is the max height of the port.

Max box height is 21.5”? Subtract 1.5 and 20” is your max port height.

20”x10”= 200”

If I am wrong don't murder me.

I’m using the box I am building as reference.

My enclosures max dimensions are:

60”Wide

30”Tall

17”Deep

2 Fi BL 12”

Specs:

Fs: 35.2 Hz rounded down to 35

Qms: 4.68

Qes: .25

Qts: .24

Sub OD: 12.5”

Cut ID: 11.125”

Mounting depth: 6.75”

Mounting depth is 6.75 so the port has to be at least 6.75 wide

Port Length:

1130/FS/4*12 = port length in inches.

So I got 1130/35/4*12 = 97 inches

Port Size:

I used THIS chart for cone area.

2 12’s have 200” of area.

The internal area of the port has to be around 200”

So height X width = 200”

15.5*13= 201.5"

So a box for my 12’s tuned to 35hz needs a 97” long port that is 13” wide by 15.5” tall.

Box

using my max Dimensions I lay out my port. I am using a double baffle since my subs will be firing up.

I start the port on the right and add the port width measurements of 13”

The height is going to be the port widths + the Wood

1.5+13+.75+13+.75 = 29”

So I know my box will be 29” tall.

Now I draw a line down center of the port. I am looking for the length of the right side up to the dotted line and the left side.

First measurements are 21.75” 7.25” and 13.75”

21.75+13.75+7.25= 42.75”

My port needs to be 97”

97-42.75= 54.25

I need 54.25” more of port length.

The port will end at the center of the rear sub which is 6.25” from the wall

6.25+54.25= 60.5

divide that by 2= 60.5/2= 30.25”

each length will need to be 30.25” long

Add your port lines up

21.75+7.25+30.25+13.75+24= 97”

Measure 6.5” from center of the left and right of the center line to get the final left side width.

You end up with a box that is 52”x29” with 97” of port.

Raise the port walls to 15.5” add the front and back of the box and you get 17” deep

Final dimensions are 52”x29”x17”

For the 45’s I measured in 13” and 13.75” from the corners and made a 45 degree lines

Measure my Cutouts for my Baffle:

Added a few 1” dowels

Final:

Cut Sheet

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