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Talked to the people at TREO Engineering about air space for the (3) 12" TREO SS subs. They said each sub needs 2 cubic feet of air. I was thinking one comman box for all (3) 12's. I want to fire them upward and the port to fire at the tailgate. This is going in a 76 K5. So how big will a box with 6 cubic foot of air space be ??? I don't know anything about building a box for subwoofers.
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Well, I've answered this same question for you before.....but let's do it AGAIN:
First, if you need to get 6 cu ft of airspace inside the box, there are a few things you need to know ahead of time....like the speaker displacement (manufacturer will provide this) and the port displacement (if you are building a ported box).
Once you know how many cu ft (or cubic inches) those things will eat up, you need to make sure that they are added in to the space calculation.....for the sake of arguement, let's say that you end up needing an extra 10% of airspace for account for all the other "stuff" that will be encroaching on that box volume. You would have 6.0 cu ft + .6 cu ft (10% of 6.0) for a total of 6.6 cu ft. or 11,404 cu inches. (6.6 X 1728) <- 1728 is the number of cubic inches in a cubic foot. /forums/images/graemlins/thinking.gif
NOW.... there are some dimensions inside your truck that I call "non-negotiable"....these are lengths or widths that simply CAN'T be exceeded because the sheetmetal is in the way. For example the distance between your wheelwells is a "non-negotiable" distance and it's something like 50" wide. If you want to keep the height of the box even with the top of the bedrails, then you have another "non-negotiable" dimension of about 19".......
SO.....what do you do with these non-negotiable numbers? You divide them into that total cubic volume number (11,404 cu in)....and what you'll find is that if you divide out your height, and width......the resulting answer will HAVE to be the length of the box (the front to back dimension in your rear cargo area).....
Therefore: 11,404 / 50" (the width) = 228. Then divide this number by the height (19" in our example) and the resulting answer is:
228 / 19 = 12 inches.
So, a box that's 50" wide x 19" tall x 12" deep will give you 6.6 cu ft.
The problem is that you wanted your speakers facing UP, and the box is only 12" across in that dimension, so you might want to make the box 12 tall, and 19" deep instead.... the point is, with that formula.....you can pick 2 non-negotiable dimensions, and calculate the third one EVERY TIME.
It really works...... /forums/images/graemlins/deal.gif