Single 12" Sealed MDF Subwoofer Enclosure (Belva MDFS12)

12-inch Sealed Car Sub Box Made with 3/4" MDF and lined w/ Polyfil (1.0 cu ft airspace 12SQTC)

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• 3/4" Medium Density Fiberboard Construction
• Durable Black Carpeting
• Pre-Lined with Poly-Fil
• Gold Speaker Terminals

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Built for Bass

You've got an awesome subwoofer there, pal. But where's it gonna go? You can't just throw that thing in the trunk and call it a day. Don't worry, Belva's got your back. With superior construction, great features, and everything you need for bass, you'll be ready to pass up that entry-level box you've been eyeballing.

You get quality boxes with solid 3/4" MDF because nothing else will do the job right. You want to flex your windshield, not your box's innards. You get polyfill built into the box, making sure your subs perform perfectly. On top of that, you get a box that's CARB Phase 2 Compliant, meaning your box won't emit as much nasty formaldehyde as the competition. Better for your bass and better for you.

While other brands use less-than-optimal 1/2-inch MDF, we've got 3/4-inch MDF to make sure you get all the bass you can handle. Why risk a busted box? Belva's the obvious choice when it comes to giving your sub a good home and giving you the low end you're looking for.

General Features:

  • Single Sealed 12" Enclosure
  • Internal box volume: 1.0 cubic ft
  • High Quality 3/4" MDF Construction
  • Durable black carpeting
  • Pre-lined with Poly-Fil
  • Seams are fully caulked for better efficiency
  • Gold post terminals for clean and easy wiring access
  • Box Dimensions: 14-1/4"L x 14-1/4"D x 14-1/4"H
  • 30 Day return policy

Specifications & Details

Box/Enclosure specifications
Subwoofer Size
Subwoofer Cutout Shape
Round / Circle
Box Type
Number of Subs/Speakers
Box Style/Shape
Cutout Diameter or Length
Maximum Speaker Depth
Total Box Volume
1.0 cubic feet
Box Volume (Each Chamber)
1.0 cubic feet
Wood Thickness
Number of Terminals
Terminal Type
Binding posts (banana clip ready)
Box Exterior Color
Box Finish
Tuning Frequency
Port Details
Tuning Frequency
Warranty and Return Policy
Parts Warranty Duration
30 days
Labor Warranty Duration
30 days
Warranty Provider
Sonic Electronix

Item Details


Model Number:




Internal SKU:


Internal Product ID:


Customer Ratings & Reviews

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great value great sound

Nice box preassembled. All you need is terminals and short piece of speaker wire!! Once sub is muonted if new season it!! Then pound on it !!!
Nice tight sound!

By mike on October 14, 2013


found this helpful.

Fantastic Value for such a great item!

After receiving the Box, I promptly installed it and began tuning my subwoofer and amp. Wow. Not only did the bass sound punchier, which was expected, it sounded much clearer and did not overlap my OEM speaker in my 02 Jetta.
The box is definitely a key component in my audio setup and I would recommend this product to any of my friends looking for this type of product.

By MJones on September 17, 2013


found this helpful.

Great box for a great price

Very nice box. Extra bonus with the poly fill. Deep black carpet color looks great. 12" sub dropped in perfectly without any sanding. Can't beat the price with free shipping!

By Mike on October 7, 2013


found this helpful.

Works Great!

Bought this as replacement box. Couldnt hear a differnce but sounds the same as my old box.

By D on December 1, 2011


found this helpful.

Great Box and Great Deal!!!

Wanted to repower a old 12" MTX speaker. Replaced with a new box and as good as new! Speaker hits as hard or harder, than it did when it was brand new. Thanks........

By ChaDog on September 17, 2013


found this helpful.

Awesome box

The box was a great purchase and a great deal. Very happy with my purchase.

By box user on October 31, 2013


found this helpful.

Great quality

This is very solid for small price. Great quality enclosure here.

By Stephen on November 12, 2013


found this helpful.

Well Constructed, Nice Box

I only give it 4 Stars because I purchased this originally because the specs listed this box as having a 1.25 cu. ft. internal volume. I ideally need 1.25 cu. ft. for my Kicker Comp12. However, this box is 1.0 cu. ft.. The webpage was updated after I received mine. Still I kept the box, put a little more stuffing in it than required to make the sub think the box is even larger.

Other than that the box is very well constructed. I you were using it for a high powered 600W RMS or greater sub I would reinforce of the corner joints with wedges or corner braces for added stability (remembering to subtract the volume of the wedge braces, especially, from the internal volume). Meaning This box would be good for high powered shallow mount subs with a Vas slightly under 1.0 cu. ft..

By Me on September 14, 2013


found this helpful.

Great Enclosure For The Price!

I received this enclosure via a package deal from Sonic Electronix with the Infinity Kappa 120.9w. They are a great match! The enclosure matches the subwoofer manufacturer's recommended sealed enclosure size.

This enclosure arrived in perfect condition, with no air leaks. I have tested out the Infinity 120.9w woofer with 600 wrms pounding to bass heavy music, and the enclosure held strong.

The terminals provide the option for banana plugs or direct wire from the amp using the screw down option (which I chose because I have no banana plugs on hand). I may be getting some banana plugs just for easier connect/disconnect.

The fact that the enclosure carpet (black) matches my Lexus trunk carpet perfectly is a nice bonus.

I did add some extra poly-fil - the amount that came with the enclosure was one thin layer around the interior of the box - not enough for my liking. I bought some poly-fill and packed the box half full.

This enclosure should last a long time - it is very solid and well made. I also like that the sides are inset about 1/4", allowing for easy grip when lifting the enclosure.

By David on August 21, 2014


found this helpful.

Subwoofer Enclosure

I bought Subwoofer on this site. Send to a friend in Ukraine to participate in the competition for mobile media (car audio).

By Vlad on December 22, 2014


found this helpful.


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