Since i have a square room, most spots give terrible accuracy with bloated, high or mid bass. The spot i have the sub is very accurate. It's right behind my right speaker and blends great.
However the sub is on the edge of the wall, where the front living room meets the hallway left wall. The sub is under the right very edge of the tv entertainment system, about 2". That's why the sub can't be anymore than 19" tall.
The sub is 14-1/4" wide, and is flush with the edge of the wall, where it meets the hallway. Anymore than that 14-1/4", and the sub sticks out in the hallway. That's why I didn't want anymore than 15" wide. With the sub backed all the way to wall where the cords are only bent enough to get by without damage, and leave about 3" from the rear port of the sub to the wall, is 22" overall. 21" for the sub with its power cord plugged in, and its knobs and connectors taken into the dimension. So sub can be no more than 19" tall, 15" wide or 21" deep. My front living room wall is short because it has the hallway to the right and a foyer to the left. Just long enough for tv entertainment center, front speakers, and stereo component rack. That's why sub is behind the right front speaker.
Right sidewall has bookshelves leaving only corner which has poor sound. Rear wall has chair and sofa, leaving only corner which has poor sound Left wall is all picture window with chair, table, and light, leaving only spot that has weak bass.
So I'm limited to front wall, behind right front speaker for good subwoofer sound quality.