I am getting ready to build a box for a btl n2 18 and I found these cut sheets on the forums Fi links to from their home page.

http://www.soundsolutionsaudio.com/forum/topic/44518-btl-box-cut-sheets/

The dimensions just so happen to be perfect to fit in my escape in the area I have left. I have 3 questions.

Is this a decent box design?

Is there any problem laying the box on its back to fire sub up port up? ( too close to back hatch I think to fire back )

And it shows the hole the sub goes in as 16 3/4 diameter. Is that right for an 18 inch btl? I figured it would be close to 18 inches?

Those boxed are good designs.

Your can try the box in any orientation, and see which works best for you.

Yes the cut out ID is 16.75"

Those boxed are good designs. Your can try the box in any orientation, and see which works best for you. Yes the cut out ID is 16.75"

If i flip it on its back will i need any additional bracing or reinforcement or should it be strong enough by itself?

I have never seen an 18 in person so i guess the 16.75 just kinda weird ed me out.

Edited February 5, 201312 yr by QmarcesQ

I would definitely use some sort of bracing, no matter the orientation. Some 1.5" dowel rods or 2x2's will do great for bracing and not use up enough internal space to affect tuning any noticeable amount.

For example, three 2x2 braces, two at 21 inches long to brace top to bottom, one at 19.75 to brace front to back on one side of the sub only take up .142cuft of internal space. Dowel rods would be a little less than that. With 7cuft of space that .142 just won't make any noticeable difference.

Alton got it covered, could not have said it better.

I would definitely use some sort of bracing, no matter the orientation. Some 1.5" dowel rods or 2x2's will do great for bracing and not use up enough internal space to affect tuning any noticeable amount. For example, three 2x2 braces, two at 21 inches long to brace top to bottom, one at 19.75 to brace front to back on one side of the sub only take up .142cuft of internal space. Dowel rods would be a little less than that. With 7cuft of space that .142 just won't make any noticeable difference.

what would you use to secure the dowel rods in place?

the adhesive i was told to use for the box is titebond 2 or an industrial floor sealer, and coarse thread drywall screws to hold it all in place. is there any way you recommend other than that? this will be my first box build

cut 2 4x4 inch squares or so with a hole in the center for the dowel to slide in. slide the squares on the dowel set the dowel in place in the box then push the squares up to the inside walls of the box with plenty of glue on all contacting wood.

like this

cut 2 4x4 inch squares or so with a hole in the center for the dowel to slide in. slide the squares on the dowel set the dowel in place in the box then push the squares up to the inside walls of the box with plenty of glue on all contacting wood.

Idea stolen! Tanks

Much appreciated y'all.

is there an adhesive you guys prefer to use over any other?

and someone suggested i line the inside of the box with acoustic dampening material, is that really necessary i have never seen that before on any box i have had built for me.