Is there a way to calibrate the expression pedal?

[MojoAxe]

There is a significant dead space where nothing happens when I rock the expression pedal back.  I took some measurements of the pedal on my Stadium and I found that the total rotation of the expression pedal is 16°, however no changes are registered for the first 4° of travel from the toe-down position. 

 

For instance, the Position parameter of the Wah effect ranges from 100% to 0%, but position indicator remains at 100% until the pedal has been rocked back a full 4°, at which point the parameter begins to change from 100 % to 99%, 98%, 97%, etc. 4° is 25% of the total travel of the pedal which seems excessive, so I'm wondering if there's a way to calibrate the pedal so that it begins to change parameters as soon as the pedal starts to rock back.  

[gbr13697]

I have had similar issues on Boss expression pedals, but caused by mechanical problems and poor engineering, not calibration.  If there are dead zones where the resistance does not change in parts of the pedal travel, there is nothing for the calibration to map. This happens on the heel end of the Boss pedals, and amounts to 25-30% of the pedal travel.

I have just checked my Helix Stadium, and found that there is a dead zone of about 17% at the toe end. I suspect that this is a deliberate gap before it gets to the EXP1/EXP2 toe switch. The pedal must unlink from the potentiometer as it moves beyond the maximum rotation of the pot, or it would just break the pot.

For the way I use my pedal, the parameter reaches 100% at toe-down, and the extra dead travel does not bother me. In fact I had not noticed it. By contrast, the dead zones at the heel end of the Boss pedals seriously annoyed me.

My work around on the Boss pedals was to insert a pad under the heel end of the treadle, to restrict its travel and stop it as it reached the dead zone. You could put a pad under the toe end of the Helix pedal in the same way, but that is obviously not an option if you do use the toe switch.