For full-range floor-standing speakers, start out with the speakers as far out from the back wall as practical or your “significant other” will abide; remember they have to live there, too!. 2 to 3 feet should be your minimum with 5 to 6 feet desirable. In a very small room (i.e., 10 feet x 10 feet) figure on getting the speakers about 3′ from the back wall. The “Rule of Thirds” applies here, so a larger room will allow for speaker placement farther from the walls. Smaller speakers on stands and mini-monitors in particular may benefit from closer proximity to the back walls (it may help reinforce lower frequencies) though it’s still a good rule to keep them at least 2 to 3 feet out. Space the speakers as far apart as practically possible (5 to 10 feet center to center) while retaining at least 2 to 3 feet between their outside edges and the side walls. Check that the distances from each speaker to the back wall and side walls are the same (symmetrical).
Start with your listening chair about 8 feet back from the speakers and exactly equidistant from the side walls. Measure from the center of one speaker to the center of the back of the listening chair. Move the chair straight backwards and forwards until the measurement is the same as the distance between the center of the speakers. You will now have your head located at the approximate apex of an equilateral triangle described by the centers of the speakers and your listening position.
If the tweeters are at about the same level your ears will be when you’re seated, (or slightly above if the speaker is a simple two-way design) proceed to the next step. If the tweeters are too low, try tilting the speaker back slightly until the tweeters point toward your head. If this still doesn’t do it, consider putting the speakers on stands. If they’re too high, tilting the speakers down a bit may work, but in that case you’re better off padding or raising your seat until you reach the right height. Depending on the speaker design, you may find the optimum position for your ears to be right between the tweeter and midrange drivers.
Attach a piece of string or cord to the center of the back of your chair, long enough to reach beyond the speakers. The measuring string shouldn’t be stretchable. Unless the speaker manufacturer recommends facing them straight ahead, angle (toe-in) the speakers toward your listening position by standing directly behind them, sighting squarely over their tops, aligning them with both hands. Use the measuring string to confirm that both speakers are exactly the same distance from your listening position and angled the same amount. Just pull the string out to one corner of a speaker, hold the measurement, and swing it over to the other speaker to check that it’s the same. When all four measurements are the same, your speakers will be equidistant from and aimed directly at your listening position.
Now it’s time to listen. Play a record with decent soundstaging and a single vocalist center stage. If the soundstage you hear is nice and wide but the images in the center are blurred, move the speakers closer together. Make your string measurements again. If the center images are well-focused but the soundstage isn’t very wide, angle the speakers away from the listening position a little at a time until the soundstage becomes it’s widest without losing the center fill. Keep in mind that many speakers seem to like being pointed at your shoulders rather than directly at your head. Use your string again – your measurements will now be the same for pairs of corners, not all four. Once you find a position that seems to offer the best compromise, try moving your listening chair straight forwards or backwards a little, paying close attention to subtler changes in perceived frequency response (i.e., highs rolled-off or too bright, forward or backward shifts in the soundstage). You may find an ideal chair placement, or “sweet spot”, depending on the dispersion pattern of your particular speakers. If you decide to move the listening position more than a foot or so in either direction, you should start all over with the spacing vs angling tests.
Excellent results can occasionally be achieved by listening at a greater distance from the speakers, but then room interactions play a major role in perceived sonics, i.e., you wind up listening to your room rather than the original recording venue. Alternatively, there’s what’s commonly referred to as “nearfield” listening, which has distinct advantages. Of course, if your room is small, you may not have a choice. Many rooms are not symetrical to start with, are L-shaped, or have different wall materials, etc., so you may have to resort to some simple room treatments to get the best sound.
Above all, don’t be afraid to experiment. These are just guidelines, not hard and fast rules. However, if you insure equidistant spacing and angling (with the string measurements), you will vastly improve the overall performance of your system. Naturally, if you do discover a “sweet spot”, make sure it’s your chair!