Expression Pedal doesn't seem to be linear

[kirky_roger]

I got my Yamaha FC7 Expression pedal and connected it to ableton. I'm able to map the pedal to any knob or slider but it seems that if I push the Pedal down the changing of the value isn't linear.

Let's say I have a knob with values from 0 to 127. My Pedal is at minimum position, value is at 0. I move the pedal very gently forward (0.5 cm) but the knob goes so fast to a value of about 70-90 that I would almost call it jumping. Now there's still 90% of the way to go to get to the maximum postion of the pedal, where the value is just slowly increasing until it gets to 127.

Does anybody have an idea what the problem might be?

Thanks!

[ChiefNugget]

I think it's a 50k linear taper pot in the FC7, which should work fine with most MIDI controllers. There is no real standard value for the pot resistance, but 10k linear seems to be more widespread. Linear taper is generally preferred over audio taper for MIDI expression pedals.

The FC7 may have the tip and ring wired in reverse polarity from what your MIDI controller expects to see. I've had this issue with other expression pedals and they had similar symptoms. You could use two TRS Y-cables to invert that polarity, wire up a cable that inverts the polarity (tip to sleeve and sleeve to tip from one end to the other), or open the FC7 and rewire it. I'd try the cable test before rewiring the FC7.

[theophilus]

I got my Yamaha FC7 Expression pedal and connected it to ableton. I'm able to map the pedal to any knob or slider but it seems that if I push the Pedal down the changing of the value isn't linear.

Let's say I have a knob with values from 0 to 127. My Pedal is at minimum position, value is at 0. I move the pedal very gently forward (0.5 cm) but the knob goes so fast to a value of about 70-90 that I would almost call it jumping. Now there's still 90% of the way to go to get to the maximum postion of the pedal, where the value is just slowly increasing until it gets to 127.

what are you connecting it into? it sounds sort of (i think) that your pedal is linear, and whatever you are plugging it into expects logarithmic (like a volume pedal).