3 box designs for 2 btl 12's

[RE XXXv3 31]

Foreward fire in a trunk, which of these three boxes are better. The smaller the box the closer the back of the box is from the back of the sub. All are from RE's box calculator. Each box has 16 square inches of port per cubic foot, the first two are off by -.003- & +.008 sq in. The box is 23-26 deep, is that bad for dampening? How far should the back of the magnet be from the box?

2 Fi BTL 12" 4-6kw @ 1ohm

2.46 cubic feet each @ 34.75 HZ with 78.75 square inches of port, box face is 17 x 37. Port 5.25 x 15. 1" MDF/1.25" spacing.

2.719 cubic feet each @ 32.78 HZ with 87 square inches of port, box face is 16.5 x 37. Port 14.5 x 6. 1" MDF/1" spacing.

2.8125 cubic feet @ 32.7 HZ with 90 square inches of port, box face is 17 x 37. Port 15 x 6. 1" MDF/1 & 1.25" spacing.

[thebiggmann12 14]

i would go with the bottom one just because its the biggest, and normally the bigger the lower, plus its tuned the lowest and has the most port length, so u wont have any port noise which is a plus. just my .02...im not an expert. post some pic when ur done.

[KU40 173]

I'd choose the middle one.

[jcarter1885 995]

I'd choose the middle one.

Im leaning towards the middle one also, especially with the amount of power being used.

[killa101 0]

As long as the magnet is far enough from the back wall to cool properly you will be fine. It won't be bad to have the back wall far away from the sub.

I'll let the others recommend what enclosure would be best because I do not have experience with the 12" BTL. I will, however, say that although 1" MDF is nice I would just use 3/4". There is nothing wrong with using 1" but IMO you can get just as good performance with 3/4" and some good bracing. I would use 3/4" MDF with good bracing instead of 1" with no bracing in a larger enclosure. Plus, you are going to be saving money since 1" is much more expensive (at least in my area) and much heavier.

[RE XXXv3 31]

I'm using 1" and a double baffle, bracing will take up space and airflow. If I use more airspace will it get lower and/or louder? What happends when you use too much airspace? Fi now says a maximum of 3 cubes. Can I coat the inside with resin or will it crack over time? Does styrofoam work for deadening? Can you get a trunk to not rattle completely? I could use 2 10's and put maybe 2-6" on all trunk facing sides, what's the difference between something with heavy deadening and one without? Can you have too much deadening? I thought the goal was to only pressurize the cabin and not the trunk and still use the trunk for airspace. I'm going to use rabbit joints, I'm not sure if they should be .25 or .5", I want no corners sticking out. I wanted even spacing around the subs for looks so I won't do 2.8. Some people are using 2.7 on 3kw, read that somewhere. My other sub was 1.7 or 2.2. I really wanted to use 4 sealed eclipse 12's on 3000w cuz iv heard them get looooww but they cant all face foreward. I'd use 3/4" for those, 1.75 each, what would happen if i faced two into in the cabin and two upfire at the back of the trunk? Is there a 90 degree phase? I heard upfire sucks. I used a sealed compvr 15 upfire in a trunk and it wasn't loud enough to tell. I think 4 12's sealed on 3kw will qualify for SQ and 1.75 is a 30hz tune.

[killa101 0]

I'm using 1" and a double baffle, bracing will take up space and airflow. If I use more airspace will it get lower and/or louder? What happends when you use too much airspace? Fi now says a maximum of 3 cubes. Can I coat the inside with resin or will it crack over time? Does styrofoam work for deadening? Can you get a trunk to not rattle completely? I could use 2 10's and put maybe 2-6" on all trunk facing sides, what's the difference between something with heavy deadening and one without? Can you have too much deadening? I thought the goal was to only pressurize the cabin and not the trunk and still use the trunk for airspace. I'm going to use rabbit joints, I'm not sure if they should be .25 or .5", I want no corners sticking out. I wanted even spacing around the subs for looks so I won't do 2.8. Some people are using 2.7 on 3kw, read that somewhere. My other sub was 1.7 or 2.2. I really wanted to use 4 sealed eclipse 12's on 3000w cuz iv heard them get looooww but they cant all face foreward. I'd use 3/4" for those, 1.75 each, what would happen if i faced two into in the cabin and two upfire at the back of the trunk? Is there a 90 degree phase? I heard upfire sucks. I used a sealed compvr 15 upfire in a trunk and it wasn't loud enough to tell. I think 4 12's sealed on 3kw will qualify for SQ and 1.75 is a 30hz tune.

Bracing won't really effect the airflow as long as you don't put anything in front of the port. It doesn't really take up that much space if you compared it to the volume the extra wood thickness takes up. I typically use 3/4" with bracing but if you use 1" that is fine....

Having a larger internal volume does typically mean more output and lower-extension. If you make the enclosure too big you are going to have sloppy bass. You don't want to make it too big or the sub will perform like it is in a infinite baffle setup.

Styrofoam would work as deadening but not very effectively if you were to simply put it on a panel. Deadening adds mass to the panel which will prevent it from oscillating (or at least not as much). Styrofoam is very light which makes it not very effective for deadening. If you were to put a piece between two panels it could be effective but if you were to simply attach it to a single panel it wouldn't do much.

Using resin on the inside of the enclosure is good. It will not crack unless you were to put a very thick layer on. All you need is a fairly thin coat of resin. Most of it will get sucked up into the wood but there will be a thin layer left. The resin alone is very brittle so if you put a lot on it could crack fairly easily. Resin is very strong stuff though so it would be difficult to break.

You can add a ton of deadening but there is always a small bit of rattle somewhere. But if you deaden effectively you will significantly cut-down the amount of rattle in the trunk and throughout the vehicle. It would be fairly hard to over deaden but when you can easily get to a point where adding more deadening doesn't have much of an impact. You don't need much deadening for it to be effective.

Having two subs facing in one direction and two others facing in the other can lead to phase issues. It wouldn't necessarily be a 90 degree phase but it would probably result in cancellation. Up-firing is not typically good for a couple of reasons in a trunk. The main reason I have noticed is that you will have a lot of rattle on the trunk/rear deck. It depends on the vehicle and the setup if it is really that bad but it is typically not ideal in a trunk.

[shizzzon 461]

If you plan on running 4kw total, i'd try to get as close to 6cuft NET as possible.

If you plan on running 6kw total, the middle one is preferrable.

[RE XXXv3 31]

Most likely 4k, 6k sounds like way too much. Is NET internal airspace? I can get 96 sqin of port and 3 cubes each. Is the RE box calculator reliable? Why does it look like there is an extra side on the top?