[LAU] DIY acoustic absorbers?

Hi! I recently moved to a new flat, and I've just got my studio properly setup in one of the rooms. Problem is, the room is rather horrible acoustically. As this is the room I've got to play with, I'm going to have to make the best of it acoustically. So, my question is about DIY acoustic absorbers. I'm most likely looking to build absorbers both for mid/hi-end (I'm thinking the classical rock wool ones you place spaced out a bit form the walls) and for the lower end, but I am very much open for suggestions. Here's some specs of my setup: - The room is roughly 3.60m wide, 3.40m long and 2.50m high. I think at least one wall is concrete. - My mixing position/monitors is in the middle of the front wall. I sit about 1.20m out from the wall. - My monitors are small, a set of Adam A3X (so 3" elements I guess). It basically gives very low bass response, so I can hear fairly OK down to about 80hz, rapidly declining down to 60hz where there's nothing left. - I am not terribly dependent on mixing at high volumes, if that matters. What I currently have is: - Two large bookshelves along the wall right behind my mixing position acting as diffusors. These go almost all the way up to the ceiling, and has stuff unevenly stacked at different heights/positions in the bookshelf. They cover 1.60m in the middle of the back wall. - I also have a fairly large carpet on the floor in the middle of the room. It probably doesn't do that much, but maybe it does a little. My question then is; are there any effective ways of acoustically treating this room? Of course, given the topic of the e-mail, I'm very much willing to do my own DIY solutions, if that's a viable option. What I have been thinking is doing what I mention above; classical absorber "panels", and bass traps. But, before I start anything, I'd very much like input from people who actually know what they're talking about (I'm looking at you on this list ;) ). So, does anyone have thoughts/suggestions for me? Any recommended way of doing this? Thank you very much for any help and any replies!