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I have 1 soundqubed hdc3 18" and I need to build a ported box box. Only boxes I have ever built were sealed boxes for 12's so this will be my first ported box build for an 18. I want to know how you get the measurements for the port height and width. Ik how to use the port length calculator but how do you originally find the width and height of the port. Also this will be a slotted port and the 18 will be going in a 6.5 cubic foot box and I want it to be tuned around 35hz. Does this sound like a good sized box and a good tuning frequency? Thanks

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Try this.

http://www.carstereo.com/help/Articles.cfm?id=31

Try to get as much port area as you can but don't let the length of the port exceed 1/12 of the length of the wave you are tuning to.

For example lets say you are tuning to 30Hz. A 30hz wave is roughly 37 feet long and 1/12 of that would be 3 feet. This means that the length of the port shouldn't be any longer than 3 feet or the air inside of it won't act as a single mass.

b_350_20_692108_381007_FFFFFF_000000.png

Krakin's Home Dipole Project

http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370

Krakin, are you some sort of mad scientist?

I would have replied earlier, but I was measuring the output of my amp with a yardstick . . .

What you hear is not the air pressure variation in itself

but what has drawn your attention

in the two streams of superimposed air pressure variations at your eardrums

An acoustic event has dimensions of Time, Tone, Loudness and Space

Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears,

thus no formula can achieve a definite effect for every listener.

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That means that the lengths and widths of the port AREA will be 13.9" or as close as you can get to it.



Try looking through this thread and downloading the program.


b_350_20_692108_381007_FFFFFF_000000.png

Krakin's Home Dipole Project

http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370

Krakin, are you some sort of mad scientist?

I would have replied earlier, but I was measuring the output of my amp with a yardstick . . .

What you hear is not the air pressure variation in itself

but what has drawn your attention

in the two streams of superimposed air pressure variations at your eardrums

An acoustic event has dimensions of Time, Tone, Loudness and Space

Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears,

thus no formula can achieve a definite effect for every listener.

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I don't know why I don't get it but I want the port to be the height of the box on one side and the sub will be on the other side of the box. By the way the sub and port will be facing up. the box dimensions are going to be H18"xW41"xD20" so the port height will be 16.5" but then what do I need to make the width so I don't have port noise I played with the Torres calc. And came up with 16.5Hx2"Wx5"L which would give me a tuning frequency of 35.6 hz is that what it's supposed to be

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You don't have to have 193" of port area; that is ideal.

That being said, a 16.5 x 2 port is not going to work with that sub. It needs to be at LEAST 16.5 x 4.5.

Not in front of a computer to see what works with the box size you gave.

Current system:

1997 Blazer - (4) Customer Fi NEO subs with (8) American Bass Elite 2800.1s

Previous systems:

2000 Suburban - (4) BTL 15's and (4) IA 40.1's = 157.7 dB at 37 Hz.

1992 Astro Van - (6) BTL 15's and (6) IA 40.1's = 159.7 dB at 43 Hz.

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Oh okay, then just use the height you need to get the port as tall as the box, then find what ever length you need to get the area as close as you can to 193 in2.

So say your box is 22 inches tall (external measurements, as in outside of the wood). You then subtract 1.5" for the wood thickness (assuming you are using .75" MDF), which brings you to a port height of 20.5".

Then you need to find a number that gets you as close as possible to an area of 193 in2. This number comes to 9-10" if you can fit that big of a port along with the net volume you need for the enclosure.

I just went ahead and came up with a quick design.

I could only fit an area of 174.25 in2 without exceeding the limit of 1/12 the length of the tuned wave.

HDC318_zps095d6097.png

Make sure you use the Torres port calculator I linked earlier to help you with the tuning, as you will (from my understanding) be using a 3-common wall port. This will lower you tuning quite a bit compared to a port that doesn't share any walls with enclosure.

b_350_20_692108_381007_FFFFFF_000000.png

Krakin's Home Dipole Project

http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370

Krakin, are you some sort of mad scientist?

I would have replied earlier, but I was measuring the output of my amp with a yardstick . . .

What you hear is not the air pressure variation in itself

but what has drawn your attention

in the two streams of superimposed air pressure variations at your eardrums

An acoustic event has dimensions of Time, Tone, Loudness and Space

Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears,

thus no formula can achieve a definite effect for every listener.

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You have the right idea now, but you don't really have to have a port that big. 100-120 sqin is enough for that sub in a car application.

Current system:

1997 Blazer - (4) Customer Fi NEO subs with (8) American Bass Elite 2800.1s

Previous systems:

2000 Suburban - (4) BTL 15's and (4) IA 40.1's = 157.7 dB at 37 Hz.

1992 Astro Van - (6) BTL 15's and (6) IA 40.1's = 159.7 dB at 43 Hz.

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