I know mdf and fiberglass is the most common. But what type of birch wood and what thickness is needed for a sealed 1000rms 12" sub box? Is there anything else better than that? I know people that can get any type of wood cheap so cost isnt that important.

 

3/4" birch would work.

 

baltic birch is the best but hard to find and real $$$...i used birch ply from HD for 2 boxes and I love it. the wood is alot lighter too.

 

for baltic birch. It does take a bit of tracking down to locate it, but you can typically talk to a custom cabinet shop (if you have one nearby) and they will probably have some or can order it for you. I bought a 10'x5' section for about $60 if that gives you an idea of the cost.

Otherwise, 3/4" MDF is always a good option as well.