Hi Brock, Thank you for these really useful advices. It’s exactly what I’d like to do : create a Diatonic preset in my H9 and send #CC to change the scale/key according to the song.

I’ve tried to program that with my Musicom Lab EFX-LE, that allow to send #PC and #CC in a same preset. But the problem is that the EFX send informations simultaneously. If I send only #CC the H9 get it and change the scale/key. But if i send #PC and #CC in same time, the H9 change the preset but not scale/key, even if the  algo is already loaded.

Would you have a solution for  that problem ? How to change algo and key/scale with a simple preset in my EFX-LE ? 

How many milliseconds the H9 needs between #PC and #CC to take the whole informations ?

Thank you for your help.

Stephane