Down4sound PRO-FAB Birch FLAT PACK 2 12 | 2 12 Sub Box | DIY Dual 12-Inch Ported Subwoofer Enclosure Box

(13 reviews) Write a Review
MSRP: $249.99
— You save $80.00


Are you in the market for a top-quality from birch wood ported 2 12 inch sub box flat pack? Look no further than our flat pack sub box, designed to give you the ultimate in flexibility and convenience when assembling your own subwoofer enclosure kit.

Crafted from high-quality materials, our dual 12 inch sub box flat pack includes ALMOST everything you need to build a durable and long-lasting subwoofer enclosure kit, all without breaking the bank. The flat pack design makes it easy to assemble and customize your sub box to your exact specifications, so you can enjoy the perfect sound quality every time you hit the road.

Whether you're a DIY enthusiast or a professional installer, our flat pack sub box is the perfect solution for upgrading your car audio system. With its superior design and easy-to-use components, you'll be amazed at how easy it is to achieve outstanding sound quality and deep, rich bass.

So why wait? Order your DIY PROFAB 2 12 inch sub box flat pack today and experience the ultimate in convenience and performance. Our subwoofer enclosure kit is designed to meet your every need, with a customizable design and premium components that are built to last. Don't settle for anything less than the best - upgrade your car audio system with our flat pack sub box today!

  • 4.0 Cube Dual 12" Enclosure
  • Subwoofer cutout - 11 1/16"
  • .75" Birch Wood
  • 31Hz Tuning
  • Mounting Depth- 15"
  • Plastic terminal Cup
  • Plastic Bag
  • Foam Corners
  • Double Wall Shipping Box 
  • Good for up to 3000w Rated Power (Any higher power than this and we highly recommend you get one of our custom hand built heavy duty enclosures)
  • Designed by Bassahaulic Productions 

L x W x H: 32.5 x 20 x 15.25 INCH

  • all the pieces to build a box, except terminal, glue, and screws


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Warranty Information

Warranty Information

Your new Down4Sound product is covered by 1 limited warranty if purchased from Down4Sound or an authorized Down4Sound dealer. This warranty does not cover improper installation, accidental damage, misuse, abuse, improper wiring, operation of unit outside of listed specifications, or any product that has been modified or repaired by anyone other than Down4Sound. Your warranty covers defects in materials and/or workmanship ONLY and is not an insurance policy. The warranty only covers the original owner of the amplifier.

All warranty returns must be accompanied by the original sales invoice or receipt. You must contact us to request an RMA number prior to sending any returns via the RMA request form on our website. You are responsible for the cost of shipping your product back to us for warranty examination. If your product is covered under warranty, shipping back to you will be at no charge to you – if your product is replaced/repaired outside of warranty you must pay for return shipping and repair bill prior returning of the product or if no defect is found you are required to pay for return shipping only.

At the sole discretion of Down4Sound your product will be either repaired or replaced when it is being covered under warranty. In the event of shipping damage due to improper packaging on products being returned to Down4Sound the customer is liable for the cost of all damages, necessary repairs, or replacement. Be sure to properly pack your return!

*  Extended additional warranty purchased on amplifiers take in affect from the date of purchase and must also be stated on orginal sales invoice or receipt. 



Refund/Return Policy:


Down4Sound - Hours of Operation

Monday 6am - 9pm PDT
Tuesday 6am - 9pm PDT
Wednesday 6am - 9pm PDT
Thursday 6am - 9pm PDT
Friday 6am - 9pm PDT
Saturday 8am - 4pm PDT
Sunday Closed
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13 Reviews

  • 5


    Posted by Brendan on Mar 29, 2024

    Great box amazing quality Only thing is was missing the down 4 sound decal was not in the box

  • 5

    DIY flat pack 12 box

    Posted by james ziya on Mar 10, 2024

    Box came in perfect condition and was delivered on time easy to assemble,not much to say but it’s one hell of a deal

  • 5


    Posted by Brian on Mar 08, 2024

    So I ordered this box, inspected it no damage. But before I got to assemble i decided to convert this to a single sub box. So I went to Home Depot and had a 3/4 inch birch plywood cut the dimensions of the baffle. Assembly was easy. However there are no grooves for the pieces so you’re stuck holding the pieces for a few minutes while the glue hardens. Another thing is the actual pieces of wood aren’t numbered as the diagram shows so you’ll have to visual verify each piece before gluing. I used #8 1.5 inch premium wood screws. I painted the box with latex gloss black paint. I haven’t used yet so I can’t say how it sounds. I also used flex seal spray around all the edges to ensure no air leaks. I changed my mind on my setup this is why I chose to convert it to a single sub box. I plan on wiring the sub and strapping amps. Just a daily driver build no spl.

  • 4

    Not bad real wood maybe a little revision good price

    Posted by Jay on Jan 12, 2024

    I purchased this, took at least a week to come in 7 to 10 days more like it. I guess that's to be expected because I'm on the east coast. Now as far as the quality goes, it seems like it's real wood and it's okay however, I would not just say that anyone could put this kit together you kind of have to know a little bit about woodworking and how things go together and you have to be careful so you don't chip or split anything or break pieces. Some of the pieces like the top and the bottom and the front with the speaker cutouts have pre-drilled holes not a few pieces like the side pieces and the port pieces have no pre-drilled holes some people might say that you can just glue the whole box together, but I wouldn't recommend that if you are using powerful subs that are fairly heavy, you always want to use screws too. So When putting the box together It does not include screws that would be a great addition so you wouldn't have to run to the store. However, I'm sure most people need screws to install the speakers I think the problem is some people might not know what they need for hardware. Now if you don't have the right hardware you can possibly damage the box crack and split the wood when trying to put it together. I picked up some #10 2-in flathead Phillips zinc coated screws at first went to install one and I did not drill a pilot hole first and the wood cracked now when I went to install a second screw I pre-drilled that time and the wood just about cracked so you got to be careful what size screw you use number 10 is too big also 2 in too long and it's not needed. I went back to the store and I picked up some #8 1-1/2 and I went with those They seem to work good. You could try to order some of these fancy SMD number 15 blackjack screws which I didn't try they might work out too. Now the important thing here is counter sinking and pre-drilling because only some of the pieces have pre-drilled holes. You have to make sure you go all the way through to the next piece so you have the drill the whole deeper into the next piece of wood You could do that with a regular drill bit however a countersink bit Is the proper way you want to sink the head into the wood for a cleaner look That's why the flathead screw is appropriate. You don't really want the heads of screws sticking out also, you don't want the wood to crack so pre-drilling through both pieces and countersinking helps with this. You want to make sure you go in enough with the bit for the countersink hole as well after the drill bit went all the way in I went in about halfway on the counter sink If you do this, you shouldn't have any problems. Overall, the box seems fairly solid once it's put together. However, like a few people have mentioned, the corner screws will intersect so you won't be able to screw into the factory holes on every corner you will have to drill your own hole in a couple of places and make sure you drill far enough away from the other screw so it does not hit it and you will be fine the box will still be sealed pretty good. One other thing is that If you try to screw down the port It is tricky once the top and the bottom covers are on and the thing is all glued in you kind of have to measure once maybe twice to be sure You want to double check before you start drilling holes because for the average Joe it could be easy to miss. So if you drill just a little to the left or a little to the right too much now you've got a tiny hole in your box at the top of the bottom and who wants extra holes. You probably don't have to screw down the port to the box on the top and the bottom but I figure it will add extra strength so I tried. Now the only other complaint was that the top part of the box that had the logo on it had a scratch going across it and the logo the wood inside it was kind of dark almost burnt like looking I might end up staining the whole box.

  • 2

    Dual 12 birch flat pack

    Posted by Andrew on Dec 31, 2023

    Ok so I got my flat pack delivered in 2 days after ordering. Was well packed however the front baffle was warped and has a little crack by one of the sub cut outs. Also there's no pre drilled holes for the port pieces and the pre drilled holes on the corners are too close to the edge as well so I had to drill new holes so the screws wouldn't run into each other on the corners. Not to mention the plywood has multiple chips in it as well. Tried to return or exchange it for a new one but was told it's not returnable even though it was only opened and inspected and not assembled. So I said F it and assembled it. Enclosure came out decent however the 45s for the front baffle are to wide and actually block a little of the sub cut outs also the sub cut outs are 11" on the dot not 11 1/16 as described so have to modify this as well. Honestly wish I would have ordered a flat pack from Gatley or GP Audio instead. Live and learn I guess. I wouldn't recommend this to anyone.

  • 4

    Flat pack subwoofer enclosure

    Posted by Robert Glass on Dec 22, 2023

    easy to put together finishing this week trying to put bed liner coat on it to make sure it is air tight

  • 5


    Posted by Ryan Kemmer on Dec 03, 2023

    Very very happy with this. Real deal 13 layer birch. Quality is impressive. I have no complaints. (2) B2 riot 12’s on 1800 rms and it SLAMS. Definitely hits the lows. Was going to add a second baffle but once I finished and applied 2 coats of polyurethane, it’s definitely SOLID. Definitely build this with a couple long F clamps. In the end, there is nothing even comparable for the price I paid for this. It looks and sounds custom.

  • 5

    Flat pack box

    Posted by P.luis on Nov 03, 2023

    Good quality and easy to assemble. Sounds good

  • 5

    Very happy with the box!

    Posted by Brian Burchett on Oct 20, 2023

    Clean straight cuts. Good quality and it sounds great! The pre-drilled holes on the corners are too close to the corner so I drilled a couple holes of my own. Also high quality terminal cup!

  • 5

    2-12 diy flatpack

    Posted by Great diy! Almost cheaper than just the wood! on Oct 10, 2023

    So I built this box, but added in an extra baffle so there'd be 2 layers at 1.5" on the baffle, left out the inside corners to try and have the. Tuning end up the same & it's awesome! You'll never get a better built box thatthan one you can reinforce yourself! Sounds frikkin awesome!

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