Hi Grumpy,RE: Baltic Birch "Your finances may dictate the type of wood to use. Since you mention reusing the plywood baffles..."With planning to reuse the baffle panels, which I would not do re vent location, I got the feeling there might be a cost/savings issue involved here. Hence my suggestion of lower cost Fir plywood VS pretty expensive Birch. But he can still use even lower cost particle board if he wishes. For the record, below is what JBL says about box material (The Most Commonly Asked Questions About Building Enclosures, P. 5). Regards,Richard