Thanks to all for replying I live in a southern state where humidity is high I know the difference between plywood,MDF and partical board I use MDF for pattern makeing for my SCMI CNC I buy the best I can fine. But the moster still gets to It. I would perfer to have plywood . I plan on getting a pair soon. That's why I would like to know when Klipsch started useing MDF. Glenn