I have only built boxes for singly sub woofers but my question is when building a box for 2 subwoofers should I put a board inbetween the two woofers on the inside or just have it a rectangle open on the inside and mount the two woofers in it?

 

It doesn't really matter when you are doing a sealed enclosure to be honest...about the only benefit to be gained from adding a seperator is that you can still run one sub if you blow up the other (after re-wiring of course)...

Actually, from what I have seen the interaction between two subs can be a benefit usually...

 

yeah, like P_J said, you don't need to and it makes the sub box way easier to build by not separating the compartments. The only problem you can run into if you make a really big sub box, you may need to add bracing to the inside so the larger walls of the box don't vibrate excessively.

 

I have 2 12's and built each in it's own box. This is because the box is very large and two of them would make installing and removing the box from the trunk would be very difficult cause it's soo heavy. Then I used brackets to bolt the two boxes together to help with security (try getting a 4'x2.5'x1.5x box which weighs 120lbs out of a trunk).