The Ekdahl FAR - Calibrations

Automatic calibration

The bowing motor speed, bowing pressure and mute all offer automatic calibration. As machines are not infallible and programmers certainly are not (meaning me as of this writing), the automatic calibrations may sometimes not do a great job and may have to be run two or more times in order to work properly. Furthermore you have to do the calibrations in the proper order or it will not work.

The most basic calibration is the bowing motor speed calibration, this measures the minimum and maximum speed of the motor. This is done at assembly and should in theory only have to be done again if you change the bow motor voltage or for some reason replace the motor. If you are using a bowing wheel that puts an abnormal strain on the bowing motor you may also have to do this.

Usually you start with the bow pressure calibration. This should be done any time you change the string, bowing wheel or change the physical position of the pressure motor. This calibration tries to gauge where the bowing wheel first touches the string (the engage position) and where the pressure makes the motor exceed its power limit (the max position). The rest position is set to a preset value below the engage position. This calibration uses the previously measured min and max motor speed as the basis of it's tests.

Second you run the mute calibration, this test needs to be performed when the position of the mute motor has changed, a string with a different thickness has been put on the instrument, or the bridge heights have changed. The mute calibration works by playing the fundamental of the instrument and digitally analyzing the sound of the pickup while moving the mute into different positions. Therefore the instrument must have gone through the pressure calibration and it should be reasonably in tune, if this is not the case you will most likely get garbage values.