I need a quick box bracing 101

[Dr. Slam 10+ year member]

I'm building a 4 Cubic foot box for two 12s tuned to 35 hz. Dimensions: 30w, 17.5h, 21d. The chamber is going to be shared and the port is L shaped. I've been search for bracing tips for hours and all I see is terms thrown out like dowels, window, 2' 2', etc... where exactly do I brace and what type of brace do I use? A pic or diagram would be really helpful.

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[Dr. Slam 10+ year member]

Nobody?

 

[Kangaroux 5,000+ posts]

All you need to do is just brace areas that aren't really connected to anything. There is no "right" brace to use, I normally just use some spare MDF and cut 2x 2" wide pieces and attached them together to form a "T"

 

[Dr. Slam 10+ year member]

So for a box thats basically gonna be built like this, where would I brace? The middle of the left side and the left side of the port?

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[Dr. Slam 10+ year member]

Suggestions?

 

[THATpurpleKUSH 5,000+ posts]

This is how I like to do it:

 

[Dr. Slam 10+ year member]

appreciate the pics bro. im going to to try to build mines like the 3 sub box you have since mines will be a similar type of enclosure and see how that works. im guessing by the pic i dont need to brace the sides then huh

 

[southernboom88 10+ year member]

in smaller applications ive used corner brackets from the hardware store rather then take away the airspace with mdf braces, pretty sure they would work fine in a larger application along with the mdf braces.

 

[bubbagumper6 5,000+ posts]

Just remember the more bracing you add, the more airspace you're taking up, the more you're changing the tuning...

 

[JerryEllis 10+ year member]

i would just build your box thicker... then there isn't any interferance inside the box..

 

[THATpurpleKUSH 5,000+ posts]

i would just build your box thicker... then there isn't any interferance inside the box..

Double baffles/thicknesses don't always stop box flex. If you add a lot of bracing, just bump up the airspace a little to compensate. 2x2s eat up airspace real fast.

 

[JerryEllis 10+ year member]

Double baffles/thicknesses don't always stop box flex. If you add a lot of bracing, just bump up the airspace a little to compensate. 2x2s eat up airspace real fast.

yeah, thats true. but if you design it right, there won't be any box flex. but i was just throwing that option out there

 

[Dr. Slam 10+ year member]

I keep seeing 2x2s mentioned, can somebody show me an image of these being used because I don't know what it is and can't picture a 2 inch by 2 inch piece of mdf being useful.

 

[JerryEllis 10+ year member]

in the second pic that was posted, the one with the mtx in the box, the 2x2 in the wood being used inside the box for the brace. it is a 2x2 piece of wood

 

[THATpurpleKUSH 5,000+ posts]

^^^yep 2x2 is just a 2x4 cut in half. Its the size of the rough cut before the piece is ran through a planar for smoothness. Its really only 1.75x1.75iirc. I like to use 1.5in oak dowels but they are kinda pricey and pine 2x2 is 1.50 per 8ft by me so I gave 2x2 a shot on my last build as seen above.