Doing a thread search, I've seen requests for this going back years and I'm shocked this hasn't yet been taken care of:
For sound and feel the Kemper Profiler rotary speaker effect is so much better than my HX Effects, (and while my Boss Rotary pedal had the features i need and sounded good, I noticed a drop in presence when in bypass.) But despite the advantages of the Kemper effect, for the things I use Rotary Speaker for, the slow speed is too slow and the fast speed is way too fast. If you can adjust the rate of virtually any other mod effect and you can adjust the ramp time between the fast and slow settings, why hasn't an an adjustable minimum and maximum rotor speed been added to the Rotary Speaker effect?
I can't tell you how many times I've suggested this over the years, just to be ignored. I don't understand why this would be any harder to program than anything else this amazing company has done.