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Discussion Starter #1
I'm going to be building a ported box and want to make slot ports. Should I used the same port volume as a round port? RF suggests 4" ports 8" long which is 100.5"cu which would be a 14" tall port ~7" long. That seems pretty short from most of the designs I've seen.
 

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how many 4" ports? 100cu inches of port area is massive!

14 x 7 for a slot port? you have done something wrong. unless that box is for (10) 18" subs with 50 cuft, lol
 

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Discussion Starter #3
One per speaker. I was thinking about making a box with a common enclosure with one longer slot port.
 

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One per speaker. I was thinking about making a box with a common enclosure with one longer slot port.
a 4" port has 12.5 sq in of port area. depending on the sub and how much power you are throwing at it. that will be a little lite. port velocity will be pretty high
 

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Discussion Starter #5
a 4" port has 12.5 sq in of port area. depending on the sub and how much power you are throwing at it. that will be a little lite. port velocity will be pretty high
I don't plan to use round ports. I'll be building a box about 15" tall so the port will be 13.5". I'm just trying to figure out width and depth. Can I make one port 200" cu for both subs?
 

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I think we have a break down here, lol

that is not how you tune a box. a 4" port that is 8" long (making 100cu inches) is not the same as a 13.5 x 2 x3.7" port (even though that is 100cu in) the 4" will tune MUCH lower

ex:

4cuft box with 4" x 8" port: tuned to 27 hz
4cuft box with 13.5" x 2" x 3.7" slot port: tuned to 46hz
 

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Discussion Starter #7
I think we have a break down here, lol

that is not how you tune a box. a 4" port that is 8" long (making 100cu inches) is not the same as a 13.5 x 2 x3.7" port (even though that is 100cu in) the 4" will tune MUCH lower

ex:

4cuft box with 4" x 8" port: tuned to 27 hz
4cuft box with 13.5" x 2" x 3.7" slot port: tuned to 46hz
Well...then I'm lost. Haha. Is there a calculator for slot ports?
 

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Well...then I'm lost. Haha. Is there a calculator for slot ports?
To calculate the port length of a round port, enter the diameter of the port (D), the box volume (Vb) in cubic feet, and the desired tuning frequency (Fb). Here is the formula we use: ((14630000*(D/2)*(D/2))/((Fb*Fb*Vb*1728)-(1463*(D/2))))

that is the formula. but this might be easier ;)

Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators


just remember when you are biulding it, that port volume MUST be subtracted from the box volume
 

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Discussion Starter #9
To calculate the port length of a round port, enter the diameter of the port (D), the box volume (Vb) in cubic feet, and the desired tuning frequency (Fb). Here is the formula we use: ((14630000*(D/2)*(D/2))/((Fb*Fb*Vb*1728)-(1463*(D/2))))

that is the formula. but this might be easier ;)

Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators


just remember when you are biulding it, that port volume MUST be subtracted from the box volume
That link doesn't seem to work.
 

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Discussion Starter #10
I found this which makes it pretty easy.

Port Length Calculator

Now for 2 speakers in a common enclosure do I just double the length? Double the width? Don't do that and run two ports?
 

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I found this which makes it pretty easy.

Port Length Calculator

Now for 2 speakers in a common enclosure do I just double the length? Double the width? Don't do that and run two ports?
that one works too.

with a common chamber box, you put in the total box volume for the port calculator. you only need 1 port for both subs. as long as you put the correct tuning freq in the calculator, it will have done it for both subs. you are tuning the box not the subs! you can put any sub you want in that box and it will be tuned to the same freq. how the subs interact at that freq will change from one sub to another, but the tuning freq will not.
 

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Discussion Starter #13
that one works too.

are you planning on running a common chamber box or two seperate boxes?
Well...neither. I haven't exactly figured out what I'll be doing. I have an oddly shaped trunk so I'm just figuring out what I can do.
 

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Well...neither. I haven't exactly figured out what I'll be doing. I have an oddly shaped trunk so I'm just figuring out what I can do.
I edited :) go back and read, i noticed you said that it was gonna be common chamber
 
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