For a 12'' Zcon in 3 cubes at 32hz. How big does the box need to be gross? I can do 30 wide and 15 high, trying to figure out how deep the box needs to be.

http://products.soundsolutionsaudio.com/index.php/product-information/zcon.html

 

Pre-Designed Enclosures

Figure out the port area you need. Then see how long that needs to be for 3 cubes. Then you can figure out how much more space than the 3 cubes you need. . And remember the sub and any support displacement . . And dont forget to account for the thickness of the wood

Wasn't trying to do all the math, I prefer to let someone else design and build it, just wanted to make sure I could fit the 3 cube box in and out the trunk before I had someone build it for me.

Find somebody to do it for free, or ask and pay for it : I usually use Ram-designs. It's "cheap" and efficient.

Good luck !