I am using CAD right now to try to make a 3d design of my box. My question is if it is an 8 cu ft. box before displacement with external aeroports, what kind of internal bracing am I going to need even with a double baffle? This is getting a fully loaded 18" BTL by the way, with a Sundown 3000d. If I use 3/4" MDF will I have a problem with too much flexing? Also one question this is my first build, first system and I want to know what your guys preference is on MDF from different suppliers. All I really have around here is a Menards and I work there so I can get a small discount on it there. I just wondered what you guys think of the quality of Menard's MDF compared to other. Also I have seen a lot of guys just use bolts instead of terminals and they swear by it. Your not gonna be able to see it in my trunk setup anyways so I'm thinking about doing that.

Your definitely going to need internal bracing.

Would I need metal bracing or maybe like swiss cheese bracing or what? basically I am looking for the best way to brace it using the least amount of space.

That is a good question. I am going to need to brace my box I'm about to make. My plan was to take the scrap pieces of MDF and just cut it into triangles and sticks and screw away

The problem is I want a way that I can easily find out the displacement of my bracing because it's going to be ported.

the best easy to calculate thing you could use is 1x1 just add all the length up and divide by 1728 to get displacement use 1 rod per sq ft and you should have no flex with a single layer of mdf

In doing that how would I place the 1x1's? just glue them to the peices of MDF to help make it heavier or would I make them standing up like pillars. This is going to be top firing ported towards cabin. So the double baffle is going to be on the top.

menards mdf sucks,,, goto lowes or home depot..

Menards wood is flaky lookin and breaks real easy, i mean u can see and feel a texture

Lowes or home depot the wood is smooth and u can tell its been pressed real nice

bracing

http://mobile.jlaudio.com/support_pages.php?page_id=166

and yea the bolts and nuts work nice, just make sure u label them

Well lets just say lows and home depot are over an hour away from me, what something to use other than MDF then?

birch but its a lil more expensive

I used MDF from Menards. I looked at the same stuff at Lowes and HD. They were the same in appearance and texture. Just make sure its MDF and not Particle board. The guy saying to use 1 inch is right. I have a 15 and just cut an extra panel. using my jigsaw I cut out 4 small squares and used that as my main brace. It looks like a plus sign with a square around it of 1". My box does not flex at all. Was easy to figure displacement.

Most boxes flex, and the minimum I would do would be like this: http://www.creativesound.ca/pdf/sealed-SDX15-131107.pdf

I hope the guys at Creative Sound doesn't mind, but their plans are great. Some very serious builder said he never built a box that had a larger unbraced surface of 4". Calculating the shelf bracing is easy, if cumbersome, just measure the volume of each shelf and calculate each cylinder shape that you remove, add them up, and subtract.