@rixthetrick, Broad-band absorbers can be bought from the likes of GIK etc. who charge crazy amounts for a simple thing so I prefer to make my own. There is much info on how to DIY them and a search on the net will turn up lots.
With an overhead panel (or cloud) and if you have sufficient height an excellent absorber can be fabricated. The thickness of and the distance from the wall or ceiling is what determines the frequency range of absorption. That's why carpets and thin drapes only effect a narrow range of frequencies which is not what we are trying to achieve.
Usually a frame 4" deep is built to accommodate 2 x 2" thick Owens Corning 703 fibre panels. These come in 2'x4'x2" With a ceiling absorber a frame 4'x6'x4" is worthwhile so don't waste effort on less. In the 4x6 frame you place 3 doubled up panels sided by side. Cover the frame in some nice fabric by stapling it to the back edge of the frame and attach it to the ceiling. Broad-band absorption in place! A pack of 6 panels is available for about $80 I have bought panels from demolishers for about $10 each.
Now for the best part: if you don't mind the looks and have the height you can vary the distance below the ceiling. Placed flat against the ceiling is fine but it's effect can be enhanced by lowering it from the ceiling. I suspend it by a few links of light chain from cup hooks. Greater distance from the ceiling will extend the lower frequencies that are absorbed. 2" helps, more if you have the height. I have hung some with the front of the frame 2" (edge closest to you) and the rear about 5 or 6" below. I like the look and it further broadens the range.
A friend's wife asked for the panels to be separated so we made 3 frames 2'x4' and spaced them about 3" apart and the end result was rather smart.
These can/should be used as first reflection point absorbers.