room gain?

[jwmbro]

What do you mean by "subsonic"? The first mode would be much lower in frequency. But we're talking about acoustically small rooms, not halls.

Sorry, I meant infrasonic.

 

[markus76]

An EQ can not change the modal behavior of a room. If the output of your speakers are heavy at 50Hz, sure, use an EQ to fix that. If your room has a build-up at the listening position at 50Hz, don't use an EQ to fix that. You should install some bass traps instead.

let's say the variance at some problem frequency is 10dB from one side of the couch to the other. Using an EQ does nothing to change the variance problem.

With enough force, I can use a hammer to drive a screw, but it isn't the correct tool.

Only multiple subs or an unpractical amount of absorption can change the seat to seat variance. If one has to optimize a single position only, EQing can be an easy fix.
This is the frequency response at my listening position (one subwoofer in a room corner, elevated to 3 ft; DSpeaker Anti-Mode 8033):

An externally hosted image should be here but it was not working when we last tested it.

 

[jcx]

I believe Toole and Geddes both point to multiple subs in diverse spatial positions to give different mode couplings for each, then you can have enough degrees of freedom for eq of the multiple subs to give OK response over a reasonable listening region

 

[davygrvy]

an unpractical amount of absorption

There's more in the toolbox than just absorption... diffraction from an LFD (which is big) and specular with regards to the wall and ceiling angles. Sonotubes can make great helmholtz resonators and even act as diffusers when mounted on the wall.

 

[markus76]

Sounds not very practical for domestic living rooms.

 

[davygrvy]

sonotube resonators, easy

 

[markus76]

Building something might be easy but it's still not practical for listening spaces that double as living rooms. What you really want is effective broadband low frequency absorption that works below and around a room's Schröder frequency. Single Helmholtzabsorbers are not flexible and effective enough for their size.