2 SA 8's with a aero port box

[dagormz]

Hello, this will be my first box build. I designed a 1.33CU box last night. Once i calculated the port length for 1 6" aero port it said i needed a 41" port length! Now i am very confused and could not find anything useful online. Any help for a newbie?

Thanks,

Nolan

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[CheЯRyMan]

I built a similar box about 3 weeks ago heres a link to thread http://www.caraudio.com/forums/miscellaneous-car-audio-reviews/610452-cherryman-custom-enclosures-dual-sundown-sa8v2-crossport-box.html If you want to use a aero in a straight line you will need a box at least 48 inches long. If you decide to put bends in your aero your efficiency will decline and any advantage gained by using a aero will start to decline. A aero this long will need a considerable amount of internal bracing to hold t up. At these lengths aero's loose their appeal and limit design options over a traditional port.

1.28ft^3 per chamber gross

41" port = .42ft^3. 4x3

Fb=32. F3=28

.78 ft^3. Net volume after all displacements

Outside dimensions

43x11hx14.5 deep.

 

[dagormz]

Ohh, i figured i really screwed up my math somewhere. So is it possible to use an aeroport with these at all. I have a very limited amount of space in my subie and can't really go any longer than 35" long.

 

[dagormz]

Would it be possible to put an elbow on the pvc inside the box to extend the port length to 41ish?

 

[CheЯRyMan]

Put bends in it or exit the aero out of the side but the length will decrease to around 28 inches and that will be the new frequency@28 inches

 

[CheЯRyMan]

From my build I had a one 4x3 port @ 41" per chamber which displaced .84 ft^3 total for both ports. One 6 inch aero @ 41" displaces .67ft^3

 

[dagormz]

What do you mean it will decrease the length to 28"?

 

[CheЯRyMan]

Doing the port in one piece exiting the side assuming your width max is 36 a 28 inch long port would be max length

 

[dagormz]

So I couldn't run a pvc pipe back and forth through the box to get the 41" or is my logic completely screwed?

 

[Dmac1991]

a 6" aero is a tadddd bit on the high side for port area, which is why you need it so long to bring down the tuning

I'd go with a 3" aero, maybe even 4"

 

[snyderd758 10+ year member]

A 4" would work perfectly

a 6" aero is a tadddd bit on the high side for port area, which is why you need it so long to bring down the tuning
I'd go with a 3" aero, maybe even 4"

A 4" would work perfectly 9.44 sq In per cube it would need to be 18.8 inches long to tune to 35hz total length flare to flare.

 

[dagormz]

Okay, thanks guys. Now Sundown does recommend a 8-12in^2 port area for each e8, a 4" port would be about 14in^2. is that okay because it's an aero?

 

[CheЯRyMan]

4 inch aero is 12.56 sq." so you will be fine

 

[snyderd758 10+ year member]

Okay, thanks guys. Now Sundown does recommend a 8-12in^2 port area for each e8, a 4" port would be about 14in^2. is that okay because it's an aero?

7-9in^2 is what is usually recommended for an aero they are aittle more efficient then a slot port or straight pvc which is usually 12-16in^2. Your enclosure will be 1.33 cu ft so 1.33/12.56=9.44in^2 per cu ft. Don't forget to take into account the displacement of the port from the total volume of your enclosure as well as the subs displacement.

 

[dagormz]

Thank you guys, I came up with a new design. It's 1.5 cubes, has a 3" aero port that is around 6 inches long, tuned to 36Hz.

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