Fourm Key Calibration Guide

Calibrating individual keys for poly-aftertouch is simple and only requires a few steps. If you are looking for a lighter or heavier feel across all keys, try adjusting the Aftertouch Curve Global setting before running calibration. 

When should I calibrate?

When pressing into a key's polyAT sensor, the feel and range of travel should be relatively close from key to key. Black keys and white keys will have a slightly different feel and range of travel, but this is to be expected. We recommend calibration if keys feel off, if keys reach max too quickly, or if keys don't reach a maximum assigned value. 

What does key calibration do? 

Key calibration simply sets the max pressure value for an individual key. In short, you push however hard you want, then press a button to set that 'maximum' pressure point. The amount knob in the polyAT section scales this max value, which can be negative or positive. If polyAT is assigned to oscillator pitch with the amount knob fully clockwise, the maximum pressure will be 2 octaves. 

How to calibrate individual keys

1. Enter the debug menu by holding Transpose Up + Down + Global
2. Use the Select encoder to scroll to item 7 'Key AT Cal', then push the encoder down and press 'inc'.
3. Press and hold down an individual key to a comfortable maximum pressure, then hit 'inc' to set the max value.
4. Repeat step 3 for any number of keys.
5. Press 'Dec' when complete.

How to calibrate individual keys while hearing audio 

It can be helpful to hear audio while calibrating to get a sense of where the max value hits in a musical application. To do so, follow the steps outlined below. 

1. Initialize a basic program by holding Transpose Down + Program
2. Assign Aftertouch to Osc A Freq and set the Aftertouch Amount knob to max. When max pressure is applied to a key, you should hear 2 octaves of travel.
3. Enter the debug menu by holding Transpose Up + Down + Global
4. Use the Select encoder to scroll to item 7 'Key AT Cal', then push the encoder down and press 'inc'.
5. Press and hold down an individual key to a comfortable maximum pressure, then hit 'inc' to set the max value. If a key doesn't reach a perfect two octaves, pressing 'inc' and setting a new max value at a lower pressure should improve the range of travel.
6. Repeat step 3 for any number of keys.
7. Press 'Dec' when complete.

How to return keys to their default calibration values

If needed, the default calibration values can be reloaded. Reloading the default values will overwrites any user calibration data. 

1. Enter the debug menu by holding Transpose Up + Down + Global
2. Use the Select encoder to scroll to item 8 'Re-Init AT Cal', then push the encoder down and press 'inc'.
3. Press any number of keys to return their max value to the factory default.