Placement of a single subwoofer

If you use only one subwoofer, the placement will take some experimenting to get the most out of it. There is a classical method based on a principle saying that the acoustical transmission between two points in a room is equal in both directions. This method consists of placing the subwoofer on the sofa in the best listening position (with the woofer where the head is normally placed. Then you play some good (well mixed, with bass content) recording, and finally you crawl around on the floor to find the place where it sounds the best, because that's where the subwoofer should stand! This method has been cherished in most HiFi magazines, but it has several weaknesses that might be helpful to know.

1. It is not at all certain that what is appointed, almost axiomatically, "the best listening position" in the first phase of the experiment, is really the best. It may even be a disastrous listening place, where bass of good quality is almost impossible to get. Try to rearrange the furniture, it may be rewarding. Avoid listening places in the middle of the room.

2. An inexperienced listener may have a hard time judging what bass sound is best/most true, especially when the parameter of adapting them to the sound of the main speakers, and establish correct completeness is included. To separately judge just a part of something complex is often difficult.

3. How do you know how the recorded bass notes should sound when they are reproduced correctly? This is maybe the greatest problem with all the manipulated recordings today.

4. When placing more than one subwoofer, the method is useless since you cannot reverse the process, i.e. placing the subwoofer on the sofa and simultaneously be in several places and listen at the same time. It may still be meaningful to listen in one place at the time to check that it does not sound too bad. It is however essential that they are approximately at the same distance from the listening position.

5. The method is completely subjective, and the risk to choose a sound that at the time feels groovy, but eventually, maybe after playing 100 records, appears obviously colored and makes all sources sound the same. And then you have to put on the knee protectors again...

6. The thesis of equal sound transmission in both directions is not true, at least not without reservation! This is because a subwoofer as a sound generator does not have infinitely high mechanical impedance, it will therefore play the room resonance a little weaker when it is placed in the corner itself, than when it is placed in the sofa and we listen in the corner.
As a sum up, I would recommend trying to choose a placement from acoustical considerations/scientific analysis, a placement you may check out and maybe fine tune with the sub-in-the-sofa method.