Originally Posted by erwinfrombelgium
According to Ethan Winer, the best spot is 38% distance from front to back. Second best is 38% from back to front.
Originally Posted by sdrucker
So, if you've a 24' length room, with the display maybe three feet from the front, the best spot is about 9' away from the front wall, for about a 6' viewing distance from the display?
Always from the wall(s). The best acoustically balanced spot (MLP) is always calculated from the walls; the length, the width and the height (floor to ceiling).
It don't matter where your TV or speakers are, only your walls count, and where you put your couch (chair, MLP). ...And the height too.
The rule of thirds, or fifths, 7ths, 9ths, 11ths, 13ths, 15ths, 17ths, 19ths, 21ths, ...odd fractions are the best.
In Erwin's quote above, the best spot is 38% from the front wall for the room's length (front to back).
And the second best spot (MLP) is 38% from the back wall (back to front).
In your case your room is 24 feet long, so 38% from your front wall is 9.12
feet. This is the best spot. ...Or 6.12 feet from your display.
...And second best is 9.12 feet from your back wall, or 14.88
feet from your front wall. ...Which is 11.88 feet from your display.
* 2/5 = 40% (good spot too; odd fraction...fifths)
* 3/8 = 37.5% (even
fraction...eights...very close to Ethan's recommendation)
* 5/13 = 38.46% (odd fraction...a little closer to 38%)
* 8/21 = 38.09% (odd fraction...even closer)
* 11/29 = 37.93% (odd fraction...a tiny bit closer still to 38%)
Ethan is an expert, so I'll go with 11/29 from the front wall (number one), or 11/29 from the back wall (number two) ... 37.93% is close enough to 38%
And then, there is the room's width...you do the same...odd fractions...to get close to the center, but not exactly @ the center.
For example, 14/29 of the room's width.
And last, the height; check your ears and adjust to the closest inch or fraction of an inch...always using odd fractions...your ears from the floor...or from the ceiling.
You will end up @ the perfect spot, like inside a vise grip. ...When you're there don't even move an inch.
But seriously, it's what I just mentioned above.
And furthermore, your center channel can also be measured that way, and from the front wall, from one of the side wall, and even from the floor.
And all your other speakers too; your two front main flankers...from the front wall, from their respective side walls, and the woofer driver(s) from the floor. And! You don't want the same distance from the front to side walls and the woofer drivers from the side wall to be equal to the distance from them to the floor.
Even the voice coil of your subwoofer; it should not have the same distance to any wall and floor. ...They should be all different, and as all your speakers; never a multiple of each other.
Acoustics is a serious science, and with precise mathematics. ...Very true. ...Every surface in your room is to be taken into consideration as to where you sit, where your speakers and subwoofers are positioned, with precise measurements. You have options though, because of your furniture, etc.
...From best positions to second best, third, fourth, fifth, etc.
Regarding subwoofers; usually against the longest wall(s) of your room...so that the standing waves can travel the furthest without being obstructed or bounced back by shorter walls. ...And the rule of thirds, fifths, etc., still applies.
Floyd E. Toole has some coordinates on mutiple subwoofer's positioning for various room's shapes. ..."L" shaped for example...rectangles...square like 12' (L) x 12' (W) x12' (H) is bad, real bad. There are some ideal room's dimensions, and those too follow some good mathematical algorithms for best sound acoustics. A room of 24' x 12' x 8' is no good...all multiples of 4.
Books and the Internet abound on best acoustics.