How to Solve High-Frequency Suckout in Room?

@milpai good idea. I will try your suggestion to block off the “jut-out” on the right side, but I’ll need a LOT of cardboard, and it will be tough with the 12ft vaulted ceilings. I won’t be able to block it off practically but I can partially and I will see if it helps.

@ghdprentice , I’ve uploaded photos of my room. I know the room needs to be treated, but other than the one issue mentioned here, there are no other glaring issues with the sound. Before you say it might be the L-shaped couch, I thought it was too, and tried simulating equivalent dampening on the left side, using a large amount of outdoor couch pillows and many heavy and large blankets. This did not help. I’ve tried putting large pillows on the right hand wall, and large couch seats, as well as against the island on the left. Tried covering the TV with a blanket.  I’ve tried all of these measures at the same time and nothing has helped. Lastly the second set of speakers is temporary, as I’m selling my old ones. The issue in question existed slightly before I got my new speakers. But with more detail coming through with my upgraded speakers the problem is more pronounced now.

I think @milpai may be on to something, I will try blocking off the gap on the right side.  But that is obviously not a solution from a practical perspective.   If I walk towards my speakers, the stereo image snaps perfectly into place with high frequencies coming through on the right,  just as I get to the gap on the right.

I do think treatment in the left would help as others have suggested but there is no place or wall for the treatment to go…

@nyev 

You will need a cardboard that is ONLY as tall as the speaker. And it will be only 2 feet wide to accept the first reflection of the speaker. This will direct the sound waves towards your seating position, rather than to the back of the room where they are currently going. Hope this helps.

Narrow directivity speaker like Dutch and Dutch 8c, Kii3,  would work better in that room.  Or a horn speaker maybe JBL 4367. 

theaudiomaniac, I also experiment as there is too much mid, what's the cause?

@erik_squires and @audphile1 , I was thinking about your suggestion to put dampening on the left. I was thinking that to the left of the couch, maybe I need a freestanding panel/divider with some dampening installed to it. Do you think this might help, if the panel was as wide as the couch and maybe slightly higher than the speaker?

I don’t know why this works but if I hold a pillow to the left of my left ear, it sort of centres everything, which is why I think your suggestion could be on the right track.