@hilde45, I looked at your REW frequency response curves. At a quick glance, they don't look that bad to me. Most rooms that are not custom built for audio that are well treated will still show plus or minus 5 dB below 300 Hz. I usually change the scale so I can get a good feel for the plus minus range. I would suggest you also click on the spectrograph and waterfall tabs and generate the plots. You should be able to see where your long decays are. If you have long decays in higher frequencies, that can make a room sound bright even if your frequency response is pretty flat. Also take a look at the impulse graphs. I like to see the impulse graph achieving room noise level by about 300 ms. You might like a bit more. It looks like your deep nulls are in the statistical zone where moving your mic an inch or two can really change the graph. In other words, don't pay attention to the details above 400 Hz or so. You could look at the psychoacoustic smoothing frequency response and get a feel for what kind of balance you have between low and high frequency.
I don't know what to make of the asymmetry in that sharp null close to 200 Hz. It must be associated with the room asymmetry on the right and left sides. It looks like a pretty deep null, but it is narrow, so it may not give you much trouble. But you might figure out what the exact frequency is and play that tone while you are walking around the room.
I don't know what to make of the asymmetry in that sharp null close to 200 Hz. It must be associated with the room asymmetry on the right and left sides. It looks like a pretty deep null, but it is narrow, so it may not give you much trouble. But you might figure out what the exact frequency is and play that tone while you are walking around the room.