A clearer understanding of the room generated problems and frequency response characteristics should make selecting the correct solutions a lot easier
You need to establish what the problem is .. where it is occurring .. and how to defeat it correctly with either absorption or diffusion
The other thing that is critical to understand is called .... the ÂSchroeder EffectÂ
Basically your room has a Transition Point .. above this Transition Point all frequencies behave like RAYs or BEAMs of light launching from your drivers in a straight line until they come into contact with a surface and are reflected
Frequencies below your rooms Transition Point behave like pressurizing modes .. pressurizing the entire room .. imagine your room is a balloon and you blow in and out .. the balloon expands and contracts evenly in all directions
So above the roomÂs T/P frequencies will beam like Rays of light and must be ÂAbsorbed where they strike ... below the roomÂs T/P the room will be pressurized similar to the balloon example
ItÂs not as important to know the point where your room transitions .. but the fact that it does and frequencies behave differently above and below it and must be treated separately
The problem with the pressurization is certain areas of the room naturally boost the response and add extra energy ... this is Room Gain and not to be confused with Standing Waves
The points of highest pressurization are the 4 corners of the room and at the mid point of each wall .. if you want to reduce bass energy with a resistive bass trap you need to place it in the corners where the problem is occurring and at the mid point of the wall where the pressure is also the highest
ThatÂs not to hard to understand .. above the T/P absorb at point of strike .. below the T/P absorb at the 4 corners and then any mid wall you can starting with the wall behind the speakers
The front of the room has a very large, curved, convex reflector made of wood.
I believe this is a diaphragm style Bass Trap meant to reduce the excessive energy at the mid point of the back wall
Lets start on the bottom as cleaning up the bass always improves the midrange .. so fix the bass first
In your room with the back opening into another area I would first put a basic 4 inch thick 2x4 foot Bass trap in each corner behind the speakers .. I would also add 1 or 2 more (side by side) Bass traps on the same back wall at the mid point spaced out 4 to 6 inches from the wall
What this does is dissipates some of the excess Bass energy that is created in the corners and wall mid points thus taming done the ringing
Next up the ladder and above the roomÂs T/P would be first reflections ... I understand you have issues with windows but she will never know if you toe the speakers in a bit ... this will not eliminate the first reflection problem but move the point where the RAYs hit the wall to a less offensive spot
Other issues to be treated are also all above the roomÂs T/P and behave like RAYs ...
Echo Slap or the sound bouncing between two parallel surfaces ... this could be your next move after the back wall .. place a 2 inch thick 2x4 bass trap directly to the sides of your speakers and against the side wall .. this will reduce the energy that is reflected off that part of the side wall and bounces back and forth between the the other wall causing ringing
Other room generated problems are comb filtering or the same frequency running by you ears numerous times due to being reflected and Long Decay Time (RT60s) where the note just lingers to long
HereÂs one for Long Decay times and sheÂll never see it coming ... install 6 or 8 inch curved crown molding around the ceilingÂs perimeter .. energy travels along the ceiling and up the walls and meets at the point where they intersect .. here the excess energy is reflected back into the room again extending the noteÂs ringing ...the curved crown molding diffuses the reflection and tames down the Long Decay Times