Digital Room Correction

Unless you're very lucky or specifically designed a room for audio, every room will be troubled by room modes that make the bass response uneven. It won't sound equally loud for the whole bass frequency range.

It is not practical for spaces like a living room to place thick bass traps. And even if you have them, they will not be able to make the bass response perfect on their own. The only practical way I see is using digital room correction (also called room equalization among other terms), which a DSP (Digital Signal Processor) or computer can execute. The easiest method is parametric EQ, because it won't cause much delay and can be used for real-time applications like watching TV/movies (and not lose lip sync), playing video games and playing digital instruments (like a keyboard/synthesizer) live.

This is by using PEQ. The resonances at 18 and 33 Hz are easy to explain. They match dimensions of my room. Caveats: This result is for a single listening position only. I have yet to optimize it for multiple seats. I also don't know yet what causes the broad dip between 70 and 200 Hz. I am amplifying that range with PEQ (more than 6 dB, which is generally advised as max), which may not be the best approach. It is better to understand the cause, which can help to find a way to solve the cause rather than the symptoms.