I’ve got the Expression Slider from OBNE. When I use it with the H9 the expression curve is logarithmic for some reason. The first 50% of the slider is around 88% of the range with the remaining 12% spread over the last 50% of the slider. I haven’t seen this behavior on other pedals I’ve controlled with the slider. Is there a setting I can change to make it linear?
The OBNE expression slider uses a 100 Kiloohm potentiometer. For best performance, Eventide recommends expression devices with 10 K – 50 K potentiometers. Using anything higher will cause the behavior you’re experiencing.
You could try putting a 100k resister in parallel with the slider. That would bring the total resistance down to 50k Ohms. It is not ideal but might be close enough.