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Discussion Starter #1 (Edited)
Guys,

I just finished my box in my SUV that contains 8 Alpine SWS-10D2 subs in a sealed box (all 3/4" MDF) with a solid divider sepatrating them into 4 subs on each side inside the box. My net volume per sub is .72 cubic feet per driver.

here is a link to Alpine's specs for the sub;

http://support.alpine-usa.com/products/documents/OM_SWS-101215_D4_2.pdf

What I'm considering is keeping the same box and putting ports in it for more SPL and also still have the ability to "Cap" the ports when I want to have it sealed again for more SQ and tighter bass when I want.

I realize I'm on the small size to do ported because each box of four 10s is only 2.88 cubic feet and the ports being put in will also take up .5 cubic feet or maybe more?

Alpine calls for the port to be 1" x10" x 18" long for one 10, So I was thinking if I did 1 slot per set of four 10s it would be
4" x 10" x 18" long....or would it have to be even longer being the box is on the small side? Also not sure what frequency I'd even be tuned at?

Can any of you guys with programs model that for me and see if its possible to do the box ported as it is right now? I'd like a lower tune around 30 to 35 HZ if possible for more SQ...maybe its impossible to do this in such a small box but I have to ask :)

(I can use ports as long as 24" without doing a 90 so I'd like to stay that length or less, if possible, being the box is already complete)

Thanks!
 

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This is going to be about the port air speed so what we need to know is how much power are 4 drivers getting and does your amp have a sub sonic filter. If so, at what frequency?

A few calculations show that a 4" x 10" x 24" port will tune each half of your box to 42 hz. Knowing how much power 4 subs get will determine if it needs to be that big.
 

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Discussion Starter #3
This is going to be about the port air speed so what we need to know is how much power are 4 drivers getting and does your amp have a sub sonic filter. If so, at what frequency?

A few calculations show that a 4" x 10" x 24" port will tune each half of your box to 42 hz. Knowing how much power 4 subs get will determine if it needs to be that big.

Thanks Mike.

each 10 right now is getting 350 watts RMS but at some point I may add another amp strapped to my current one so I need the port for up to 700 watts RMS per sub.

Yes it has a subsonic filter at 28 HZ but I have it turned off right now.

42 HZ seems to high, What if I mounted the ports externaly so they didn't take up any box space? How can I get the tune to 30 to 32 HZ?
 

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Discussion Starter #5
not sure why you need them?? But ok, Its 41" wide, 30" long and 11" high and all the subs fire straight up. Internal vol is .72 cubes per sub
 

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Discussion Starter #7
I cant do them on the side, but I can do them off the top of the box then angle them on a 90 deg and fire them towards front of vehicle.....did you come up with area and length for 32HZ tune?
 

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For a 32 hz tune and the power you will be using you need a minimum of 40 square inches of port area for each half of the cabinet. The internal height and width of the port has to equal 40 inches, 4" x 10", 2" x 20", 3" x 13.3", etc. Regardless of how the height and width add up to 40 inches, the length needs to be 31 inches.
 

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Discussion Starter #12
wow, that's long....not sure I can integrate it, might have to sink some of it inside the box, but that will raise the tuned frequency right?
 

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Discussion Starter #14
Mike, If I wanted to use round ports instead to make it easier what would it be? could I get away with 2 round 6" aero ports if I only used 350 watts per sub into all 8 subs?
 

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Discussion Starter #16
I would like it to play down to 20 HZ...wont that roll off my real low bass? so you're saying two 6" aero ports 24" long (1 in each box) will give me a 32 HZ tune Freq.?
 

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Without the HPF that your amp has the port air speed will be too high and the drivers will start bottoming out below 23 hz, a HPF at 20 hz would be ideal since it would protect the drivers and the port air speed would be acceptable.

Does your amp only have one HPF or is it selectable at other frequencies?
 

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Discussion Starter #18
no, it is a fixed subsonic filter set at 28 HZ with an on/off switch.

So how many 6" ports do I need per cabinet to get a 28 HZ tune? and 24" long you say?
 

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Discussion Starter #20
ok, now I'm thinking I can do this!

couple more quick questions;

What if I sink both ports inside the box and fire them off the front edge towards my back seat, do they have to be longer now to maintain the 32 HZ tune now that they are totally inside the box? if so, how much longer?

Also how much space should there be in front of the port to my back seat so it doesn't restrict the air flow?
 
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