This step is for all types of X axis. However, you may not be able to be as precise when using an original Prusa axis.

Launch the Pano Tuner app and place your smartphone on the heated bed. Make sure there is no noise in the room that could disrupt the measurement (like a ceiling fan).

Move the extruder to the middle of the X axis.

Pluck the lower portion of the belt to make a sound. Don't pluck it too hard as it might touch the x carriage and distort the sound.

Adjust the belt tension until you have a frequency close to 90Hz. Between each adjustment, move the extruder all the way to the left and right and then centre it again.

It is very important to move the extruder between each measurement, this ensures that the belt is evenly tensioned.

If your belt is new, you can repeat this procedure after a few prints. A new belt will loosen in the first several hours of use.