It's the same with the H9. You set Key, Interval and mix of each voice. For "simple" harmony effect I bought the Quadravox. Up to for voices harmony. There is also the Diatonic but it's to voice with independant delay and feedback if I remember well. I don't use these feature. May be you have a H9 Core with H949/910 algorithm which is not really an traditionnal harmonizer IMO.