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I figure i will use chipboard above and begind the the sub, green glue, drywall for finishing.

This is known as constrained layer damping and is extremely effective in reducing panel resonance. I would also suggest putting horizontal dividers inside the column to break the large panels into a series of smaller panels with a higher resonant frequency: pushing the resonant frequency above the range of the sub. MDF or ply will do just fine. Anything you can screw and glue to the chipboard.

Fred

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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!