Expression pedal for GCP

[SlapHand]

Hello!
I've tried to get my Ernie Ball volume pedals to work as expression pedals on my GCP. Not much success. They have a logarithmic response curve and push almost all the CC# from about 60% of the pedals travel and up.

What would be a good expression pedal to use with my GCP?

I´m grateful for any answers!

Thx!