People often say the reason not to use EQ for fixing room issues is that it doesn't fix the ringing of a resonance through time, only the amplitude. This isn't the case. A standard normal EQ (parametric preferably) works in the amplitude and time domains (AKA phase).\n\nYou don't need expensive room EQ systems to work in the time domain. When you make a notch on a normal parametric EQ, what this basically does is set up a resonance in an electric circuit. These resonances obey much the same laws of physics as acoustical ones; the resonance occurs both in amplitude and in time.. So when you make a notch on an EQ unit that is equal but opposite in amplitude to the resonant peak in your room, what you get is that the resonance in the EQ circuit and that in the room cancel each other out. This not only gives a flat frequency response, but also the ringing of the resonances though the time domain also are opposite and cancel.\n\nIn practice acoustic resonances in room tend to be a bit more complex than the one in the EQ unit, but it still works well and the suggestion that only physical treamtents can aid the decay rate of a room mode is false.\n\nBelow is a real world example just taken from my room today. Note the resonance at 40Hz and the improvement of the decay.\n\nThis is without EQ.\n\n[IMG]http://i608.photobucket.com/albums/tt169/tenson_uk/40Hz-BeforeEQ_zpse5bf2112.jpg[/IMG]\n\nThis is after EQ.\n\n[IMG]http://i608.photobucket.com/albums/tt169/tenson_uk/40Hz-AfterEQ_zps7ea2b498.jpg[/IMG]\n\nYou can also see 3 modes piled up near each other around 60Hz. You could EQ these with a single notch on the centre frequency and a reasonably wide Q. However as you can see they are actually 3 resonances near each other. If you EQ them out with 3 parametric EQs of narrow Q then the time domain will be much improved over just using one general EQ bank. That's why graphic EQ is not ideal for room EQ; you want to identify the individual resonances at play.