# IB Project: Need help before cutting hole in wall

Discussion in 'Archived Threads 2001-2004' started by Robert George, Mar 26, 2002.

1. ### Robert George Screenwriter

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Before I start cutting, how isolated do the two sides of the drivers have to be for this type sub to function properly?

If I place the drivers in a wall, can there we any open connection between the two rooms?

I can still do an attic/crawlspace install if the front-firing/wall install will not work.

Thanks.

2. ### ThomasW Cinematographer

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Obi

The front and rear wave need to be 'reasonably isolated' from each other otherwise they cancel. So the rooms shouldn't have a common opening that can't be sealed.

The greater the distance the front and rear waves must travel before they meet the better.

Attics or crawlspaces are ideal locations for mounting the drivers; if there is increased potential for cancelation with a room to room install.

Regards

Thomas

3. ### Robert George Screenwriter

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Okay, Thomas, now for a volume question...
Would a 121 cubic foot space (closet dims 3' x 4.5' x 9') be adequate for a front-firing IB install using 2 12" drivers?
I think this may be the last Q...

4. ### ThomasW Cinematographer

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The minimium size for the 'box' is no less than 4 times the sum of the Vas of the drivers. 10 times or greater the sum of the Vas is best.

So for example a single Shiva has a Vas of 151L = 5.3 cu ft. So a space 21.2 cu ft is the minimium for a single Shiva, 53+ cu ft is optimal. Double these when adding a second driver.

You haven't said what 12" drivers you are planning on using so calculate the requirements based on the Vas of the drivers you choose. Try to stay as close as possible to the 10X Vas.

If you have a large enough 'box' I sugggest going with a pair of 15" drivers. These will go lower, play louder and aren't much more expensive than a pair of 12"s. There's significantly less chance of having buyers remorse with a pair of 15"s. Don't be concerned about having to much bass. It's easier to lower the bass output if it is too loud, than it is to try and pump up the volume if the output is too low.

Understand that IB bass is a very different animal when compared to normal subs. There is a clarity, detail, and precision to the bass that is unobtainable with normal 'portable' subwoofers. It's nice to be able to experience it without being limited by the radiating resistance of smaller drivers.

5. ### Pete Mazz Supporting Actor

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Obi,

Reading your other post, you may have to "enclose" the back of the RPTV. The back pressure from the IB drivers will probably affect the screen.

Pete

6. ### Robert George Screenwriter

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The drivers I have are two of the type found in SVS Ultra subs. I'll put in a manifold install in the crawlspace above the TV with these drivers as my first IB project. If I am not satisfied with the output, but like everything else, building another box with 15's and using the same installation will not be that difficult.
Wish me luck...hope I don't fall off the ladder.

7. ### Robert George Screenwriter

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***Late Update***
Shit!! It won't work, at least not to my satisfaction. The roof/ceiling construction won't allow the placement of a box/vent in an area that I have to put it without some rebuilding of roof braces. Forget that.
Oh well, I guess I'll just have to content myself with a pair of custom SVS CS Ultras. But that is a subject for another time and another forum section .
Hasta manana, DIY...

8. ### Jack Gilvey Producer

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