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Discussion Starter #1
I've been thinking about and simulating box sizes for my next sub setup. I like the simplicity of IB, and I was thinking I'd try my infinity perfect 12 that way, but vented looks so apealing also, but the box needs to be sooo big.

Then I thought why not use the whole trunk as the box? you would have to seal it up real good and things would change when the trunk is open and add have stuff in the trunk, but I have an EQ for that. I figure I'll have about 13 cu ft of trunk space.

Heres a WinISP pro model:

All have a 20hz 4th order high pass and are running 150 watts. The white is 13 cu ft tuned to 18hz with a 20hz 4th order high pass. the red is the same port size, but 500 cu ft (trunk open). the yellow is the same driver IB.

So, what I'm seeing with my trunk open it will act like its IB.

Any thoughts? I'm guessing trunk preparation would be key to making this work.
 

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Interesting... can't say if it'll work or not... like everything else, it may work in theory but there usually are limits in which way you can stretch a design before negative effects are triggered.

For an IB setup, you need to make sure the front & back waves are separated (no leaks) that port would be as good as any leak (in theory) & what generally happens is cancellation no output...

Don't have a definitive answer for you, but you can always seal the port if it doesn't work...
 

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Discussion Starter #3 (Edited)
My thinking is that the main issue is making the trunk a good box. IB its only important to separate the two airspaces while with this setup the whole trunk must be sealed.

Like you said, if it doesn't work out I can just seal it up and run IB, so there's really no harm in trying.

doesn't IB into the trunk function as a semi sealed box the size of your trunk anyways? its considered IB when the box is 4x the vas correct? what would happen if you had two dayton IB 15" running IB into your trunk? with a vas of 11 it would take 88 cu ft to really be IB. How would the they act with 10 cu ft of semi sealed trunk space?

I'm guessing somewhere in between, but closer to the Qtc of 1.121 than .738 depending on how sealed it is and the output level... that is unless you open the trunk.

I'm mostly thinking out loud, but I welcome comments...

-Jeff
 

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geoffire said:
Then I thought why not use the whole trunk as the box? you would have to seal it up real good and things would change when the trunk is open and add have stuff in the trunk
http://www.sounddomain.com/ride/29935

He changed the text in his page since I last saw it. It used to state that the trunk was actually ported, just like how you plan on doing this....

racerraul said:
For an IB setup, you need to make sure the front & back waves are separated (no leaks) that port would be as good as any leak (in theory) & what generally happens is cancellation no output...
???????????????????????

HOW DOES A PORT WORK

Think of a box port not as a vent in the terms of a venting path for air to travel into and out of a box, but rather as extra cone area that is propagating acoustic energy from the enclosure to the cabin. The air in a port is fixed; it is trapped within the confines of the port walls. When the cone moves there is a corresponding change to the pressure in the box, that pressure change then causes the trapped air in the port to move either forward or backward. It moves as a solid unit, just like a speaker cone does.
^^ Edjumakashun :cool:

Tempe
 
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