This is a classic example of a system that can benefit from a properly integrated sub. In almost every room there will be a place where the speakers image best and have the most even natural response above 150Hz. There will also be a place where the speaker’s bass response will be the most even. I have yet to work in a room where those two places are the same. You likely don’t have the floor space to optimally place a sub, so there will be concessions.
In my experience, proper listener and speaker placement is always preferable to any amount/type of EQ, but your hands are tied. You’ll have to work with EQ to tame this, but try to use the absolute minimum that gets you an acceptable balance between engaging sound and a resonant mess.
And anything that you do to try to fill in dips in the response using EQ will be a disaster! What you’re seeing in that response curve is cancellations and emphases. If you can knock the peaks down, even by 1-2dB with better placement of speakers and listener (stay away from that back wall as much as possible), it should also bring many of the troughs up. You’ll be chasing a series of tiny victories that will add up to the best your system will get in that room.
I suggest that you try using a more acoustically transparent plug for the speaker ports, as the ones that come with most speakers are so dense that they create enough back pressure to stifle the natural sound of the driver(s) that share the port cavity. This won't help the excess bass but it will likely improve the overall sound.
I agree that the best way forward on the 120Hz issue is to do a nearfield measurement of each speaker separately to see if the issue is with your speakers, mic, or a room resonance. Common room resonances are often caused by light lamps, wall sconces and recessed light fixtures. If you have a signal generator, input a 120hz (+/- 5Hz) steady-state sine wave into the system and you’ll likely find the problem pretty quickly.
In my experience, proper listener and speaker placement is always preferable to any amount/type of EQ, but your hands are tied. You’ll have to work with EQ to tame this, but try to use the absolute minimum that gets you an acceptable balance between engaging sound and a resonant mess.
And anything that you do to try to fill in dips in the response using EQ will be a disaster! What you’re seeing in that response curve is cancellations and emphases. If you can knock the peaks down, even by 1-2dB with better placement of speakers and listener (stay away from that back wall as much as possible), it should also bring many of the troughs up. You’ll be chasing a series of tiny victories that will add up to the best your system will get in that room.
I suggest that you try using a more acoustically transparent plug for the speaker ports, as the ones that come with most speakers are so dense that they create enough back pressure to stifle the natural sound of the driver(s) that share the port cavity. This won't help the excess bass but it will likely improve the overall sound.
I agree that the best way forward on the 120Hz issue is to do a nearfield measurement of each speaker separately to see if the issue is with your speakers, mic, or a room resonance. Common room resonances are often caused by light lamps, wall sconces and recessed light fixtures. If you have a signal generator, input a 120hz (+/- 5Hz) steady-state sine wave into the system and you’ll likely find the problem pretty quickly.