How to understand tuning sounds in Objekt?

[Mistro17]

Not sure if I used the right words in the title. I'm currently going for an amplified electric harp sound. But I don't know how to bring the harmonics to a place where I don't hear something out of tune especially when playing bass notes along with the upper notes. Is there a set of mathematical things to keep in mind?

[jam-s]

Isn't there a tuning knob/button that should adjust the harmonics to be in tune? I think I remember something like this from the introduction videos that Ryan did.