Equilateral Triangle RuleThe fundamental rule for monitor placement: monitors and the listener form an equilateral triangle, and the listener must sit on the room width symmetry axis. The 38% rule gives a starting depth guide — 38% of the room length from the front wall — but this is a modally-friendly starting zone, not a guaranteed optimum. The final listening position should be fine-tuned against symmetry and how the stereo image behaves on pink noise.