Try to avoid multiples of two in your monitor’s placement, since you will excite the room modes of the room.
Monitors placement and listening position in the room it´s a very important factor that brings a better or worst frequency response. The situation of these element impact on nodes and antinodes in standing waves.
As a rule of thumb, you have to situate your sweet spot or listening position on 38% of the long wall it´s a starting point.
Apart from avoiding multiples of two, you need to know the room modes of your room for making a better position.
Here a great Room mode Calculator.
Let´s see an example of a room of 5,20 x 3 x 2,40 in meters.
Here we have main room modes:
Bass frequencies are our big problem on the studio. We have to situate the monitors and sweet spot avoiding resonances or pressure points as far as possible.
Maybe you are planning to build your studio. Here you have a great tool to calculate an optimal shape of the room: Room Calculator.
“With an optimum room ratio, you will have fewer problems with room modes or standing waves“
Now you are ready with your monitor’s position, let´s see isolate your monitors, to reduce coupling.