How to Stop Subwoofer Bass From Traveling to the Neighbors

Subwoofers can produce deep, powerful bass that easily travels through walls and floors, disturbing neighbors. The unfortunate thing is, that most of it travels through air. So even if your subwoofer does not have a physical connection to the floor, your neighbors will hear it.

There are a few simple and some much more complicated things you can do to minimize that effect.

1. Reduce Subwoofer Volume or Adjust Settings

Lowering the subwoofer volume, especially at night, can prevent disturbances. Most AVRs today have a built-in dynamic range compensation (some call it Night Mode) that reduces the huge jumps in volume between dialog and action scenes. A more even volume will help reduce unexpected noise traveling to the neighbor. In addition, you can use a dialog lift and dynamic loudness to make it more intelligible when listening at lower volumes. 
It sometimes can help to use a subsonic filter to reduce the very low bass.

2. Positioning the Subwoofer

Place the subwoofer away from walls, especially shared ones. Bass frequencies resonate more when the subwoofer is placed in a corner or directly on a wall. Experiment with placing the subwoofer in different areas to find the optimal spot that minimizes travel to neighbors.
Also note, that a good subwoofer position will result in a smoother frequency response (without any major dips) and a fuller sound, so you do not need to turn up the subwoofer volume that much. 

3. Acoustic Modules

Though not really isolating the sound from your neighbors, acoustic modules like bass traps, typically placed in the corners of the room, help absorb low-frequency sound waves and convert them into heat. Resulting in a better decay and overall tighter sound. The same as with a good subwoofer position, you will not need to turn up the bass to hear it, as you will have a much smoother response. 

4. Install Soundproofing

The most effective and unfortunately complicated method is adding soundproofing measures like dense insulation, and soundproofing panels. These materials help block sound from leaving the room but require good planning and sometimes a renovation of the room to make it look pretty.
One very overlooked point is doors. A soundproof door does a lot in terms of containing sound and is a must in any good soundproofing concept.
Also, do not forget any air ducts and air leaks as bass will travel through those openings.

5. Isolating the Subwoofer

The last point on the list is isolating the subwoofer. These specific absorbers decouple the subwoofer from the floor, reducing vibrations and the amount of bass that travels through the building structure.
Unfortunately, that does very little to nothing in reducing the sound to your neighbors. As we mentioned before, the sound travels through the air and not through the subwoofer cabinet into the floor.
But in very old buildings, with very poorly isolated floors this can be worth a try. At least it will reduce the vibration you feel in your feet.