It uses three or more subwoofers with asymmetrical or "random" placement. Figure 4 shows some example layouts with three subs (Geddes also recommends lifting one sub closer to the ceiling if possible). Note: as part of the optimization process, the delay of individual subs will be changed. ...
FIG. 23 depicts Loudspeaker and Color Organ placement for the Dolby 5.1 emulation. The placement of the Effects channel loudspeaker (labeled SubWoofer in FIG. 23) is not critical and is shown directly behind the listener for clarity of illustration only. ...