Acoustic Treatment of Asymmetrical/Open Room

I’m looking into treating my listening area and haven’t quite been able to get the left/right soundstaging nailed.
Overall, the issue is the room configuration itself, but unfortunately that can’t be changed. The listening position can’t be changed either due to space constraints. So this is an exercise in just making it as good as it can be.

My listening area is open to my kitchen on the right side. So there is a wall down the whole left side which is fairly close to the left speaker (1.5 ft or so), the wall on the right side is 3.5 ft away from the right speaker and extends from the front wall towards the listening position approx. 4ft and then stops to open to the kitchen.

I’ve been playing around using soundstage test tracks and positioning absorption (just using cushions/pillows etc.) and I can’t get the far left (off-stage left) position correct. It sounds like it’s coming from the right hand side even though the first reflection points on the right have been treated. It’s strange, it sounds like a lot of reverb originating from the right side of the soundstage when the voice should be originating from well outside the left speaker (I know…there’s a wall there!!). The other soundstage positions sound good.

So, I’m hoping maybe someone here has already dealt with this type of situation successfully and can point me in the right direction (without putting up or tearing down a wall or moving!!) or at least help me with the following questions as I continue my investigating/trial & error:

  1. Which speaker and wall (boundary) interactions come together to create the off-stage left (very far left) image?
  2. Is there a way to make a wall act like an open space? (ie: mimic my right side open kitchen on the left hand wall)
  3. Is diffusion the key, rather than all absorption?

Thanks for any thoughts/ideas.

Tube Traps work well for this issue, and can correct for reflections as well as bass irregularities.

@eldrick, how would corner bass traps work to open up the left side of my room so that the off-stage left image comes from well outside the left speaker?
(I’m not questioning your suggestion, I just want to understand how they would work in the context of my problem)

I can successfully widen or narrow the off-stage right side image by adding/removing absorption in certain locations but the Left side doesn’t seem to move no matter what I do. (as mentioned in original post, I’ve only tried absorption though)

I have a similar room setup and found that knocking down the 1st order reflections using 2" absorbers combined with convolution filters have worked magic.

Convolution works in frequency and time domains to correct for asymmetry. Email Thierry at Home Audio Fidelity for advice.

I use the 9-inch ones for side and back walls - they are made with one edge reflective of mid-range/treble, and the other side absorbing.
I use the larger bass traps in the closed front corner to balance with the open front corner.

You might not be able to tell, but the left side of the room is open. I lucked out and have a buddy who is a pro acoustic engineer from Colorado School of Mines with a sound level meter who measured my room first by popping balloons. Turns out the room was better than I thought from the start, but this is how the exercise ended…