Autodexr,
Unfortunately what has probably happened is that you have cleaned up the lower midrange significantly - so you now notice the room modes much more (as they last longer).
The sub has a Q of around 0.5 - so this is definitely musical not HT - your next step should be to investigate a PEQ to tame room modes - there are probably two big bumps and one of them is probably the main culprit. Room modes appear strongest as you jack it up - it is like the room "hums" as it resonates not unlike a tuning fork.
Unfortunately what has probably happened is that you have cleaned up the lower midrange significantly - so you now notice the room modes much more (as they last longer).
The sub has a Q of around 0.5 - so this is definitely musical not HT - your next step should be to investigate a PEQ to tame room modes - there are probably two big bumps and one of them is probably the main culprit. Room modes appear strongest as you jack it up - it is like the room "hums" as it resonates not unlike a tuning fork.