I am on the verge building an 8 cube sealed box for a Fi Q18 which I will be buying in the next 2 weeks. I was set on everything until I came across one question. Do I need to have a 1 inch baffle? I plan on double baffle flush mounting. I was going to build is all from 3/4" MDF with a lot of internal bracing. No polyfill since I am maxing out the dimensions.

My dimensions are: W:40" D:21" H:21" (will fit nicely in the spot of the room i picked )

Besides the baffle question, does anyone see any problems with my plans?

i've never had a double baffle for any of my systems and haven't had any problems.....but if u have the space for it i would say go ahead

Well my main question is do I need a 1 inch baffle or will 3/4" all around be the way to go.

3/4 wouldn't hurt, it wold just be heavier, lol

i don't really see u gaining anything from it though

I'd say just use 3/4" all the way around with the bracing you mentioned, then double up the 3/4" for the front baffle that the sub mounts onto.

Okay, that answers my question. Thanks a lot.