I've seen quite a few people put absorption panels behind their speakers. I understand that they need to be put at reflection points which are towards the front of the speakers on the walls and even some material on ceilings and floors. Bass traps also are placed in the corners. They look to be about 50mm thick so can't really be bas traps unless I'm wrong. What's the reason for panels behind the speakers, and if you've done this, does it work?
