The goal is to make the cabinet very rigid, to get good clean bass. Thus, either approach should be fine for that goal. I chose the 1/2" plywood (basically, I did what Wayne did), and it sounds great. I can tell you that the completed cabinets are each nearly 100 lbs! If you use double-thickness MDF, they will be significantly heavier than that.

Off the top of my head, and without thinking it through carefully, it might be easier to construct the double-thickness MDF cabinets, since you would not have to carefully measure and place the plywood (which was a minor hassle, especially with the braces).

Cheers,

jIyajbe

thank you for your reply