Subwoofer direction matters less than placement, Engadget guide says

The guide explains that low-frequency sound waves are enormous—a 40Hz bass wave stretches about 28 feet from peak to peak—so subwoofers radiate bass energy equally in all directions rather than beaming it like a speaker. As a result, a properly placed subwoofer should not reveal its location, and a slight change in orientation will not make or break sound quality.

However, direction is not completely irrelevant. Ported subwoofers, which have a vent or tube on the front, rear, or bottom, need at least 2 to 4 inches of clearance around the port to breathe properly. Blocking the port can significantly reduce bass output. Sealed subwoofers, lacking a port, are more forgiving, and orientation is almost a non-issue acoustically.

For placement, the guide recommends putting the subwoofer in a corner directed toward open space to reduce dead spots and provide an easier-to-equalize response. Alternatively, placing it along the front wall beside the main speaker often blends better with the center channel and mains. For dual subwoofer setups, placing them in opposing diagonal corners yields smooth bass across multiple seating positions.

To find the best spot, the guide suggests a crawl test: place the subwoofer at the main listening position, play a track with a steady bassline, then move around the room, listening at knee height in each potential location. The spot where bass sounds most balanced and full is where the subwoofer should go. At the end, the guide concludes that the room, placement, and acoustics shape bass experience far more than driver orientation, so experiment and trust your ears.