Why does pulling out main speakers from wall improve sound?

@jumia  

While most posts answering your question suggest pulling your speakers several feet off the rear wall, Focal, who know something about speakers, do not ascribe to this theory.  Focal uses a flexible equation to find the best speaker placement.

“Optimisation For perfectionists, here is a formula for optimal positioning: If A is the distance from the centre of the woofer to the nearest floor or wall, B is the distance to the next closest floor or wall, and C is the greatest distance (A < B < C), the equation B2 = AC defines the ideal loudspeaker position. • Example: If the centre of the woofer is 20” (50cm) away from the rear wall (A) and 24” (60cm) above the floor (B), then the side wall will be ideally 28” (72cm) away [C = B2 ⁄ A = 28” 

I found this a little confusing at first, but it became clear in short order.  There are three distances involved.  Floor to center of woofer, Side Wall to center of woofer and rear wall to canter of woofer.  The shortest distance is always “A”.  This is usually floor to center which is the only constant.  The next shortest distance is always “B”, and the longest distance is always “C”.  The distance “C” is always (B x B) divided by A. 

By example, if your floor to woofer is 24 inches, and you are 6 feet off the back wall, you would need to be 42 inches off the sides wall.  If you wanted 8 feet center to center on your speakers, your room would need to be 15 feet wide. 

In a nutshell, Focal suggests there is no rule about distance from back wall as long as C = (B x B) / A

Great thread!  Great question. Here’s my simpleton take:

The sound from your speakers bounces all over the place, like light in a mirrored room.  When speakers are near back and/or side walls, the sound off the wall comes back to yours ears so fast that the reflected sound interferes with the sound coming from your speakers. Moving the speakers into the room lets you hear more sound from your speakers, less of the reflected sound from the walls. Moving the speakers into the room can also actually help the reflected sound improve the sound of your speakers. 

Even a couple inches change in speaker placement can have outsized changes in sound quality. Experimenting with placement is a lot of fun…

According to an expert speaker guy, whom I don’t recall his name said 5’-6 is the magic number for speaker setup, the ear can pick up on the timing difference below this distance, so if your ears are 10’ from the speakers and a reflection path distance from a sound wave is 16’ then all is good, however if it’s less, then it will muddy the sound stage, so the if the speakers are 2’ from the back wall, we’ll that’s 4’ timing offset to your ears… so you pull them away 3 or more feet from the back wall to be greater than 5’-6… I think this would apply to the front wall too…

whose right… who knows… always fun to experiment though….

Steve

As I reflect back on all the hours viewing system set ups as lovely as they are with all those expensive components, I dare say most of these pictures have the speakers pretty damn close to the wall.  Dealers Display the speakers pretty damn close to the wall.  Then I began noticing a few set ups where the speakers looked weird being pulled so far from the wall. 
 

My large basement on the habitable side has my speakers right in the middle of the room and they are older and they really fill the room extremely well. I thought it was just the speakers but it was more than that.  In my other rooms and systems it's tougher to get those speakers very far from the walls, but I am rethinking things with a goal of pulling the speakers way the hell away from the walls.  Rectangular rooms are difficult where the long wall is being used for the system.  Points of egress and windows and doors make it difficult to use the Wall on the short side of the room for the system, very sad.

@aewarren ,

“I suggest you find a new dealer”

agreed.