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TallRedRider

Subwoofer Woes...need Help With Box Construction

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TallRedRider

I am beginning a number of winter projects (yes, I better hurry). I am going to run some hoses from the center compartment up to the front of the boat in preparation for installing front ballast. I also think I am going to do another bilge pump. Anyway, as part of that process, I had to remove the subwoofer. The previous owner had the system installed 'professionally' and I use the word very liberally here. I have had to redo the vast majority of it. Once again, I found some shoddy workmanship. The box is starting to fall apart. I read in most places, and believe that you shouldn't just glue a box together. My box is glued together. Plus it has some mold growing on it. So I would like to replace it since I have the box out now.

Check out the current shape of the box. They made is so that the box slopes back and at the very top touches the back wall. It is a little too small, but it has sounded great. The Kicker website says that the Comp VR 12 should have 1 cubic foot of space, I calculate the current box has about .83 cubic feet. No big deal. I could just make the same box, but I would like to avoid making beveled cuts in the MDF. That is going to make it hard to screw it together...maybe that is why they just glued it together? I am actually surprised it lasted this long.

2012-02-18185330.jpg

One problem with the box is that the bottom of the box has to be pretty shallow. If it is any deeper on the bottom than 8 inches, it will cover up the hole where the hoses and wires come through the floor. You can see the imprint of the box on the floor here, and even the existing box covers the hole a little bit, but there was enough space for the discharge and overflow hoses, but not much else.

2012-02-18185413.jpg

I would like to preserve the current faceplate if possible. It would be just one more thing to do, if I had to build another. Here is what it looks like with the subwoofer removed. But I am afraid that I am going to have to build a new faceplate, and make a new box that is just elevated above the floor.

2012-02-18185600.jpg

Anyone have any idea how I could preserve the current kickplate, and create a new box? As well as preserve that opening to run the hoses for more ballast?

If I have to make another kickplate, then what do I make it out of? Also, I have no idea where to get Malibu carpet.

On a side note, I think this is the best subwoofer enclosure calculator I can find:http://www.the12volt.com/caraudio/boxcalcs.asp

Edited by TallRedRider

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Earmark Marine

Tall,

You can use a square plus an adjustable triangle to find and duplicate the angle of the kick plate. Once the enclosure is built and temporarily in place then you can trace the opening onto the baffle surface of the enclosure so the openings in the two fixtures align perfectly.

An enclosure should be glued together with a water-resistant wood glue and either stapled or screwed together. Both methods are absolutely required. MDF splits very easily so there are a number of techniques to avoid this. Pass-thru holes on the outer surface and pilot holes on the inside surface for screws are essential to draw the two materials together and avoid splitting.

For angles use a long .75 X .75 angled block along the entire corner inside of the angled seam. You can screw through both surfaces into this block. Just add stiffening braces and corner blocks into your displacement calculations.

The more you elevate the enclosure off the sole the deeper the enclosure can be without enfringing on the steering cable radius which you do not want to pinch or place in a bind.

All enclosures have to be elevated off the carpeted sole to avoid mold and mildew growth. You have to plan for drainage and evaporartion. This also pertains to the enclosure so that you are not wicking moisture into the construction material. All coatings, whether poly resin, epoxy resin or urethane bed liners, will eventually wick up moisture via osmosis if you don't have isolation. Even a solvent-based baltic birch will delaminate eventually if not elevated. HDPE, ABS, KingStarboard or another polymer should be used as isolation pads below whatever risers, carriage or platform you are using to elevate the enclosure.

Baltic birch, MDO or MEDEX would be ideal materials for building an enclosure. MDF can hold up but the execution and final prep has to be near perfect with no seams, staple holes or screw hole depressions remaining. Any of these materials should be thoroughly coated.

Those are a few of the basics. I have a full draft on every aspect of enclosure building.

David

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Bobby Light

Unfortunately there are more installers taking shortcuts than going the extra mile, the shop that installed that system definitely took the shortcuts. There is no reason the box has to be the exact same shape as the current one. That particular box leaves a lot of width under the dash unused. MDF works great if you seal it correctly and keep it up off the floor. You can get malibu carpet from any malibu dealership.

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TallRedRider

Thanks david. Good fundamentals explained there. I appreciate it.

Bobby is right, there is lots of depth that is not utilized there.

I just realized that the other thing the stereo installers did was just stuff the anti siphon valve down into the hole since 2 more hoses would not fit with the box. So I actually have to fit 4 hoses through that hole: 2 for the siphon, bilge and front ballast.

Elevating the box off the floor would be perfect....any ideas what to build my feet with?

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Earmark Marine

Tall,

To build a platform to elevate the sub enclosure, amp panel or replacement kick plate, you should use a solvent-based plywood like a baltic birch or similar high grade. You do not want to use water-soluable MDF for this platform or a replacement plate/panel. Then it definitely should be resin-coated. Use 1/2" thick HDPE pads to elevate the platform off the sole. Send me a PM with a fax# and I'll forward an illustration on a universal platform that will have pass-through provisions for any number of cables/hoses/harnesses.

David

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Brianinpdx

Red - Build the feet from composite material. You can go to home depot and get some sheet stock and rip down strips to build up the height needed to elevate the enclosure. Or you can locate a plastics distributor locally and buy some molded 1 x 1 stock and chop it down for 1/2" or 3/4" pads. I wouldn't recommend raising the box so high that it becomes difficult to secure. Just high enough to create an open barrier to stop mold growth and create a water run. Another option if you go with sheet stock is to cut 1 layer as a footprint of your enclosure and then build up some strips beneath it to act as the sole. It's going to depend on how much effort you want to put into the redesign.

Composite material is typically sold by weight i.e. mm thickness - ts not cheap so plan accordingly. If you want a real effective down and dirty method one can also use a plastic kitchen cutting board and chop it up to create a sole. Can be found at costco for like 15 bucks. Sounds laughable but I've seen many enclosures turn out just fine that way.

Hope that helps.

-Brian

Edited by Brianinpdx

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shawndoggy

my local plastics place sells hdpe scraps for cheap. $5 or so should get you more than enough.

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Murphy8166

I am headed up to my boat today and do happen to have the subwoofer out. I will take some pictures of the install that David and Earmark did. It elevates the enclosure of the sole of the boat and provides enough room that that all the hoses and wires are not pinched nor re-routed.

Stay tuned

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Murphy8166

Here are the pictures as promised.

photo30.jpg

photo29.jpg

photo28.jpg

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TallRedRider

Thanks, Murphy! That gives me a good place to start.

Some great worksmanship there for sure.

I will have to keep an eye on that steering cable to be sure not to build a box that interferes there.

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sonny20

Here are the pictures as promised.

photo30.jpg

photo29.jpg

photo28.jpg

Unable to view photos even after clicking on them. Could you repost them as I am looking to get a box for my kick plate.

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sonny20

bump for viewable pictures

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