I read a lot about the basics (38% into the room, as many bass traps for small rooms as possible, treat first reflection points,...).
For my home studio/home cinema I'm building a riser out of three of these: [IMG=http://img260.imageshack.us/img260/9999/eurpalette.jpg][/IMG] [IMG=http://img260.imageshack.us/img260/eurpalette.jpg/1/w120.png][/IMG]
As I've learned from the kind people of GIK, I won't be getting any benefits regarding absorption with this, but I need to fill it to avoid ringing. Now, what do I need to use? The same as for an absorption panel (Rockwool, rigid fiberglass) or is there something else that would prevent the boxes from resonating?
Thank you for any tip