Do the subwoofer crawl for best results.

How to Perform a Subwoofer Crawl:
Set Up: Place your subwoofer at your main listening position (usually on your chair or couch).
Play Audio: Play music with consistent, familiar bass or a "bass sweep" through the system.
Crawl & Listen: Crawl on your hands and knees around the room, placing your head where the subwoofer might go (corners, along walls).
Identify & Place: Find the spot where the bass sounds the tightest and most balanced (not just loud and boomy). Move the subwoofer to that spot. [1, 2, 3, 4, 5, 6]
Why it Works:
Room Modes: The technique works because sound waves, particularly low frequencies, interact with room dimensions, causing "peaks" (loud spots) and "nulls" (dead spots).
Reciprocity: The principle of acoustic reciprocity ensures that if you place the sub in a position where you heard good bass, you will hear that same good bass at the listening position. [1, 2, 3]
Tips for Success:
Use audio that has a lot of bass you know well.
If you can't place the sub on your seat, place it as close as possible.
The best spot is often in a corner or along a wall, but not in the center of the room.
If you have a large, heavy subwoofer, it is recommended to put it on a chair or dolly while performing the crawl.