How do you know when you need bracing?

[Hell-Razor 0]

I remember talking to shizz and a few other box builders on here and they all said "if the box is built well enough, no bracing is needed". Well is this true?

I am working on a new box for my 15" - 38"w, 18"d, 16"h. I dont think I need bracing for a single 15" in that box, but I could be wrong (its a little oer 4.5 cuFt with port tuned to 32hz). I have been looking at other posts for people building their box and its either hit or miss for who does what with bracing. The one I just finished looking at is using bracing for a smaller box so once again, I am not sure.

Forgot to add in - I will be putting a DC Level 5 15" in the box being powered by a 3500D

Edited November 27, 2010 by Hell-Razor

[stevemead08 752]

you need bracing!

[Hell-Razor 0]

Alright.

I will get a long circular piece of wood and do it from front plate to back, top to bottom and then should I do one from left to right? I will try to get it as close to center as possible, except I am not sure about the left to right because of the port.

[Sir-Lancelot 216]

Agree with Steve, always use it. It takes up very little internal volume so why not use it?

[sq_mgb 21]

As a general rule, I like to put a brace on any panel longer than 18" "just in case." Dowels work well, as does all thread rod with washers/nuts. We used to say, "If I can throw the box off the roof and it doesn't break, run over it with the truck. If it holds up, it's ok. If not, time to rebuild it a little stronger." You can't go wrong with bracing as long as you account for the volume it takes up in the box. JL Audio has a good tutorial on their website about bracing you could look at as well.

For your box, I would use two braces on the 38" dimension that look like a window with panes that touch all 4 sides of your box. That should be enough, but you can always add more. Here is a picture of the brace I used in my box.

And how I placed it...

It's probably not the best way to do it, but it held my fat @$$ while I jumped up and down on it before I put the sides on the box. I figured if it could hold me up, I wouldn't put enough pressure to hurt it from my sub.

Good luck!

[emh9009 199]

IF you're able to, why not? it cant do much but help. unless you're really hurting for internal volume.

[Sir-Lancelot 216]

Thats hot!

Well done Rich.

[sq_mgb 21]

Thats hot!

Well done Rich.

Thank you!

[stevemead08 752]

As a general rule, I like to put a brace on any panel longer than 18" "just in case." Dowels work well, as does all thread rod with washers/nuts. We used to say, "If I can throw the box off the roof and it doesn't break, run over it with the truck. If it holds up, it's ok. If not, time to rebuild it a little stronger." You can't go wrong with bracing as long as you account for the volume it takes up in the box. JL Audio has a good tutorial on their website about bracing you could look at as well.

For your box, I would use two braces on the 38" dimension that look like a window with panes that touch all 4 sides of your box. That should be enough, but you can always add more. Here is a picture of the brace I used in my box.

And how I placed it...

It's probably not the best way to do it, but it held my fat @$$ while I jumped up and down on it before I put the sides on the box. I figured if it could hold me up, I wouldn't put enough pressure to hurt it from my sub.

Good luck!

sexy sub and sexy brace!

[altoncustomtech 773]

That looks like two subs in an IB configuration, correct?

I agree with everyone else, bracing isn't difficult to do, uses very little room inside the enclosure which isn't hard to account for anyway, and just plain won't hurt anything to have in there anyway.

[Hell-Razor 0]

Box is already mostly built. I have a wood dowel going front to back and top to bottom, pretty much cutting the box in half. I am also using 22 2" L bolts seeing as I will be assembling it inside my trunk and wont be able to screw some sides on. I will be screwing it together from the inside, gluing it with liquid nails and the caulking the inside cracks (all but the back). I figure it will take my box from 4.55 cubic feet to about 4.3 at the most. Its still a big box and I think I did well. I could have made it bigger (and should have) once I realized how much more room I can fit in the trunk (Should have gone to 5cuFt). 4.3cuFt at the minimum should be a nice improvement from a 3.5.

Thank you lance, Steve, and sq! You guys are the shiznit +1 for you all

EDIT: I should have been more clear on assembling it -- I am going to use the glue on the edges and then screw it together, then once it dries put another layer of glue on the edges, let that dry and caulk it all, It took me two days alone just to MEASURE and CUT the effing box so my wood working skills are pretty sad.

Edited November 28, 2010 by Hell-Razor

[Hell-Razor 0]

That thing... is.. wtf kind of box is that?! where are you going to put it? lol.

Once I saw that I am not going to post my box.. its sad and has a thousand pen marks on it for all my lines and whatnot.

[Mac N Cheese 90]

you can always sand it down

[Hell-Razor 0]

you can always sand it down

True true

[Julian 641]

althread from top to bottom then all thread fro, the baffle to the back..

Best bracing you can do.

[Hell-Razor 0]

I am really hoping my "everything must be within a MM" while measuring and re-cutting for this box will pay off. And the glue and L bolts dont fail me. I dont want my DC tearing it apart in a few days / weeks / months or even a year...

[valladon 4]

Thats a good general rule going by 18"s

Put up some pics of the box

[sq_mgb 21]

That thing... is.. wtf kind of box is that?! where are you going to put it? lol.

Once I saw that I am not going to post my box.. its sad and has a thousand pen marks on it for all my lines and whatnot.

It's just a simple ported box with an isobaric pair of 10's tuned waaaaaaay low. Sometimes I wish I had tuned just a little higher, but when I find something with a pipe organ or the like, I just smile when the truck shakes...

Oh yeah, this is what it looks like in the truck...

To the OP, the only way to have too much bracing is to make the box a solid hunk of wood. I just finished listening to the new Blues 5.25" components in a .75 cu.ft. box where the dimensions are 18" tall x 9" wide x 12" deep made from .75" MDF. There are TWO braces running across the 18" span and the box still vibrates with just a 5.25 and tweeter. Wonder how much more force that 15 is going to exert on your box? Bracing is your friend!

Be sure to post pics when you finish building it, and anyway, what's the worst that could happen? You don't like how it sounds? Ok, that gives you an excuse to build another one and learn from the last one to make it better.

Good luck with it, I'm sure it'll turn out just fine.

[Hell-Razor 0]

Ill start a second build thread... post some pics and whatnot. Tomorrow though, tomorrow.

[Hell-Razor 0]

Good luck with it, I'm sure it'll turn out just fine.

Thanks. Is it just me or does that box look like its ~15 feet long?

[sq_mgb 21]

In some of the pics it looks like it's huge, but it's just the angle the picture was taken at. The front of the "box" is actually the port and it stops about 2" from the closest part of my dash/firewall. The rear of the box stops about 1" from the back wall of the cab.

I don't remember the exact dimensions, but if I were to build it again I would put another brace in and divide the box roughly into thirds to help make it even more solid. The 45's in the corners helped more than I thought they would to stiffen the box up and really helped with air flow into the port. If I ever re-do it, I'll probably raise the tuning up to 24-26hz just to get a little more "boom" but I don't want to go too high and lose the bottom I have with the 20hz tuning I have now. Still, I'm not sure how much audible difference it would make anyway.