1. ## 1/3rd Theory

I was talking to a friend at work the other day. He used to be into car audio big time about 10 years ago. Anyways, a friend of his had a 94 S-10 Reg Cab, and they wanted to put 4 10s behind the seats. As you could imagine, space was an issue, so my friend discussed it with an installer at a local shop. He said that in theory, if you had more than one sub in a box, you would need only 1/3rd of the original space for the next sub. As in, if you had a 1 cubic foot box for one sub and you wanted to add another, you would only need to add another 1/3rd cubic foot to the box.
I was wondering whether this actually worked this way, and if it does, for more than two subs in a box, would you add a 1/3rd of the 1/3rd you added for the second sub, or a 1/3rd of the total space of the first two subs. My friend just fudged the theory and added 1/3rd of the box space for the first sub for the third and fourth sub.

2. ## Re: 1/3rd Theory

Nah. It'd be nice.

Two subs need twice the airspace if you want to keep everything else the same.

3. ## Re: 1/3rd Theory

never even heard of that theroy before

4. ## Re: 1/3rd Theory

The only time that's true is when you have three subs and you're adding a 4th. That way you have the space needed for 3, which divided by three is the space needed for one, which is what you need to add in order to add the 4th.

In general though, nope, no dice. Each sub needs its own space, and there's no short cuts or ways to get around that.

5. ## Re: 1/3rd Theory

Originally Posted by Another Device
I was talking to a friend at work the other day. He used to be into car audio big time about 10 years ago. Anyways, a friend of his had a 94 S-10 Reg Cab, and they wanted to put 4 10s behind the seats. As you could imagine, space was an issue, so my friend discussed it with an installer at a local shop. He said that in theory, if you had more than one sub in a box, you would need only 1/3rd of the original space for the next sub. As in, if you had a 1 cubic foot box for one sub and you wanted to add another, you would only need to add another 1/3rd cubic foot to the box.
I was wondering whether this actually worked this way, and if it does, for more than two subs in a box, would you add a 1/3rd of the 1/3rd you added for the second sub, or a 1/3rd of the total space of the first two subs. My friend just fudged the theory and added 1/3rd of the box space for the first sub for the third and fourth sub.
No.

If the subs need 1cuft each, then they need 1cuft each.

6. ## Re: 1/3rd Theory

i think that is more of a hypothesis than a theory.

7. ## Re: 1/3rd Theory

I figured so. Thanks for the replies.

8. ## Re: 1/3rd Theory

he might have been thinking of adding subs isobaric style. He would need an even number of subs.

JL site
This is typically accomplished either by placing two woofers face to face or by coupling two woofers with a small chamber. The result of coupling the two speakers is that the coupled pair (iso-group) can now produce the same frequency response in half the box volume as a single speaker of the same type would require

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