My opinion is that room treatments for midrange, treble and sound stage imaging are very important, especially first reflection points on the side walls when dynamic speakers with typical dispersion patterns (non dipoles) are utilized. Some treatments on the front wall behind and between the speakers can also provide significant benefits.
However, I'm not a fan of bass room treatments mainly because they're large, ugly, mainly ineffective and expensive. Bass soundwaves, in a typical room, just behave totally differently than midrange and treble soundwaves.
Bass soundwaves spread out in all directions from a dynamic woofer driver, are nondirectional (you cannot determine their source under about 100 Hz), are extremely long (a 20 Hz wave is 56' long, a 30 Hz wave is 38' and a 40 Hz wave is 28'), continue to bounce or reflect off of all room boundaries until they run out of energy (which results in bass room modes that are heard as bass exaggeration, attenuation and even bass absence at various spots in the room) and are very difficult to control or absorb with room treatments.
I've discovered good in-room bass response is best attained through the use of multiple subs since they smooth out the multiple bass peaks, dips and cancellations inevitably existing in almost any room for better perceived bass response, require no bass room treatments or room correction as well as increase bass detail, dynamics and impact. I use the Audio Kinesis Swarm 4-sub distributed bass array system for near state of the art bass response in my 23' x 16' room with an 8' ceiling. It works like a charm, here's a link to an Absolute Sound review of the Swarm that is very accurate:
https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/ Midrange and treble soundwaves are highly directional, we're easily able to determine their source location, are relatively short in relation to bass soundwaves (a 20,000 Hz soundwave is a fraction of an inch long), also continue to bounce or reflect off all room boundaries until they run out of energy (which also results in midrange and treble room modes that are heard as exaggeration, attenuation and even cancellation at various spots in the room but most perceive this as a desirable 'airy' quality to the midrange and treble.) and are very easy to control or absorb with room treatments.
Because of the above factors and reality, I decided to consider and configure my system as a combination of two systems, a bass system and a midrange/treble/soundstage imaging system, and have strived to seamlessly blend them as a unified, detailed, accurate and high quality whole. It's proved to be a very effective and enjoyable solution thus far without the use of much room treatment besides wall to wall carpeting with an upgraded and fairly thick underlying padding layer.
I also use dipole Magnepan main speakers that don't seem to require the traditional first reflection point room treatments that more traditional transducers usually benefit from. However, I try to keep an open mind about potential further improvements and suggestions while always being willing to experiment.
Enjoy,
Tim
