As we stated in the previous tech tip regarding subwoofer placement for surround systems, electronics is not an exact science. The real world imposes conditions on the design and function of circuits and components that cause variations in behavior and response. Additionally, what may be a fact today can become fiction as technology changes. This is particularly true in the field of surround sound, which introduces a multitude of variables in room characteristics and their responses. At present, there are certain guidelines being followed and much of the mechanics of surround mixing and speaker setup are still being debated. However, certain conventions are starting to emerge. With that in mind, let’s discuss speaker placement for surround mixing.
These are general guidelines and cannot completely describe the optimal sounding room; however, they are based on existing international standards for reference listening conditions for small- to medium-sized control rooms and provide a good starting point. Our primary goal is to create a listening room that allows us to predict with a fair amount of accuracy, how our surround mix will translate to other listening environments – particularly the home theater surround system.
While many room shapes may work, the ideal room is symmetrical along the line between the center speaker and the reference listening position. An environment with no parallel walls (including the floor and ceiling) helps prevent the buildup of low frequency standing waves. A minimum height of 3 meters (9 feet) is desirable.
Front-Speaker Placement
The three front speakers (L, C, R) should be the same distance from the reference position. The center channel should be directly to the front of the reference position. With reference to the line formed between the center speaker and the reference position, L and R should be +/- 30 degrees horizontally. Each front speaker should be the same height as the reference position (1.2 m/4 ft). All front speakers must be +/- 0 degrees vertically referenced to each other unless the center speaker needs to be positioned above or below a video monitor, forcing the acoustic centers of the three front speakers out of alignment. If this occurs, attempt to situate the speakers so the tweeters are in as close to a straight, horizontal line as possible. This may require either an inverted or a lateral orientation of the center speaker, as well as rotating the center tweeter (when possible). In any case, keep the speakers equidistant from and directed to the reference position.
Surround Speaker Placement
The surround speakers should also be the same distance away from the reference position as the front speakers and located 110 degrees +/- 10 degrees from the reference line. They may be elevated to a position not to exceed 15 degrees above the reference position, as long as they remain equidistant from and directed to the reference position.
Without the availability of a visual diagram, perhaps the easiest visual representation of surround speaker placement would be to imagine that you are looking at the face of a clock. (Not a digital one.) The center speaker would be at 12 O’clock, left and right front speakers would be at 11 and 1 O’clock respectively, (actually, they would be closer to 12 O’clock on either side) and the rear left and right speakers would be at 8 O’clock and 4 O’clock respectively. From this representation, you should be able to draw a more accurate diagram using the aforementioned angles and distances. On the other hand, if you were one of those in high school who said “When am I ever going to use geometry?” … Now would be the time.