Four rooms, one scale

One scale for all four · width × length, facing down the longer side · chair from 38% of the length · monitors in an equilateral triangle · panels at the mirror points

How the numbers are made, and where each rule comes from (all checked 2026-10-08). Each room faces down its longer side, as RealTraps advises. The chair starts 38% of the way down the room, the starting point of Wes Lachot’s rule as RealTraps gives it; Genelec instead says anywhere in the front third, at least 1 m from every wall and never the exact middle. The monitor centres sit 35 cm from the front wall, inside the “close to the wall” zone that Genelec (front under 0.6 m) and ADAM (under 0.5 m) both describe, and they form an equilateral triangle with your head. The triangle is never wider than a third of the room’s average side (ADAM); when it would be, it stays at that width and the chair comes forward instead, which in the 20 and 30 m² rooms lands it in Genelec’s front third. Reflection points come from the mirror method. A warning appears where a room breaks ADAM’s 1 m minimum spacing or Genelec’s 1 m from the walls. All of it is a starting point: move a little and listen, or measure.