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Discussion Starter #1
Ok, here is the question for all you diehard audio people on the forum, how big does it need to be. I have a pair of JL 12 inch subs, forget the exact model (got cheap, see a previous post) and I am making a custom box for them. The idea is one is in there normally, and the other is inverted (supposed to give better sound, right?). I looked up the manual online, and it said 1.5 cubic feet for the box volume for one. So what would I need for one normal, and one inverted? I have a really killer design in mind, and can't wait to build it, just need the figures to do the math. I am only designing it, than a freind is cutting all the materials and his friend (who makes alot of boxes) is building it. Should be HQ, just wish I could afford fiber glass instead :?
 
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We'd need the model number to give you help, and even there knowing what you listen to, how you like it to sound, type of enclosure you have in mind and what your main speakers are will help as different speakers have different enclosure ranges; and within that range will behave slightly differently.
1.5 per 12" for a JL is pretty dang big; are you going ported? Or are these some old W1's?
Doing one normal and one inverted theoretically yields better results- any audible real-world differences will be marginal but there's no reason NOT to do it especially if it gives the look you want.
As far as size, if JL says use x for one, then you just multiply that for how many subs you are using (in this case double it). You don't even have to worry about woofer displacement as what the one absorbs, the other will give back.
 
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It is an old pair of W1s, like I mentioned in another post, got them for free. The one i am inverting is missing the little logo in the center, but otherwise works fine. The guy who had them before me used it inverted. However, I didn't get volumes from him for the boxes, so that is why I am asking. I wasn't going ported, just a straight normal box. As for what I listen to, well, pretty much everything. Jazz, Metal, Rock, Hip-Hop, Rap, Electronica.

Do I need a divider between the two subs? or is it ok to just make it one big volume of 3?

Thanks btw
 
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Ah-hah, it is the old W1. Shouldn't make a huge difference, but 4ohm or 8ohm? How much power ya got?
I'll have to go look at the enclosure charts in the old JL book. See what I can come up for a good overall enclosure (which is probably what the 1.5cube you got is for). By the way, just to check, when you say one normal and one inverted, you mean an enclosure with both speakers visible and mounted each in their own hole, just one mounted up-side-down; as opposed to where you stick one in the enclosure and then stick the other one inverted and on top of the first one (which is an isobarik configuration, which takes half the airspace you would otherwise use for a single sub).
Anyways, let me see what I can come up with tomorrow and I'll get back with you on size.
A divider (oh, guess that tells me you aren't doing the isobarik thing... smart, ain't I? *L*) isn't necessary. It can help in high SPL applications; or if your box has a relatively large panel on any given side then it braces it; and rigidity is a good thing for speakers.
 
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Yeah, it should be the 4 ohm subs.....I matched them up earleir against the manual online. It just didn't say anything about inverting one. I just need to get the volumes (which is the same, just minus the sub displacement, or at least according to a few audio sound sites), and with that done, it is off to draw plans. I am having the normal one set at a higher physical level to make the inverted on not stick out to tall. Gonna be some pretty interesting cuts in the wood though, so we shall see how it turns out.

Thanks all!
 

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Invert = sub firing into box

If you mean something different, disregard this post.

You will need 1.5 cubic feet of air for each sub. When you wire the inverted sub, put the wires on opposite of the other speaker. This will prevent canceling out the wave. JL makes great subs.

Two 12's with about 100w/each or more should devastate the RAV.
 
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