Determining port length

[low00ranger 10+ year member]

I'm trying to design a ported box for a DD 1008a. I want a NET box volume of .75 cubic feet, and I will be using a 4 inch aeroport to tune the box to 40 Hz. How long does the aeroport need to be, and what will my TOTAL box volume come out to?

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[DeuceLee 10+ year member]

I'm trying to design a ported box for a DD 1008a. I want a NET box volume of .75 cubic feet, and I will be using a 4 inch aeroport to tune the box to 40 Hz. How long does the aeroport need to be, and what will my TOTAL box volume come out to?

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they give different lenghts tho //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

i'm going to try my winisd at home after work...see what that says...

 

[low00ranger 10+ year member]

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Car Stereo.Com

they give different lenghts tho //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

i'm going to try my winisd at home after work...see what that says...

That's really why I'm posting this. DD's website gives a port length and area for 40 Hz in a .75 cf box, but WinISD says I need a port 5 inches longer to achieve 40 Hz.

 

[MikeyB 5,000+ posts]

Sry, I could help ya but Im not on my normal comp so I dont have an programs or links. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[low00ranger 10+ year member]

Okay these are my calculations, somebody check and see if this is right.

Box NET volume - .85 cf

Port - 10" x 1" rectangular, 10 sq inches port area

Port Length - 18" which tunes the box to 39 Hz

Port runs along back wall of box so total port volume - 1.25"x10"x18" = 225 cubic inches = .13 cubic feet

Factoring in port and driver displacement(DD 8), box gross volume should be 1 cubic foot.

 

[DeuceLee 10+ year member]

Okay these are my calculations, somebody check and see if this is right.
Box NET volume - .85 cf

Port - 10" x 1" rectangular, 10 sq inches port area

Port Length - 18" which tunes the box to 39 Hz

Port runs along back wall of box so total port volume - 1.25"x10"x18" = 225 cubic inches = .13 cubic feet

Factoring in port and driver displacement(DD 8), box gross volume should be 1 cubic foot.

i'd def not do a 1 inch wide port...i'd do a 1.5 to 2 at least...give it some room to breath...

 

[Blove1991 10+ year member]

After playing with Wini a bit,, You could do the port 2 inches wide by 5 inches up for 18.25inches of port length to achieve 39hz

 

[low00ranger 10+ year member]

i'd def not do a 1 inch wide port...i'd do a 1.5 to 2 at least...give it some room to breath...

You think 2"x5" would be better? I'm only doing 10 sq inches because its 1 8 in a small box. If I even want 12 sq. inches of port area, I'd have to make the port about 23 inches long which would be impossible in the shape and size box I want.

 

[low00ranger 10+ year member]

Well I made the port 2"x5" for 10 sq inches... and it has a good bit of port noise when it plays the low notes. That's odd to me considering DD's recommendation for this sub in a .75 cf box is 11.5 sq. inches of port area.