One of the heisenbergs has resonating harshness in the frequencies which I think is coming from the bell lead preset. But either way what I would recommend doing is going to the oscillator settings right near the modulation on the right corner where you see the little knobs. You could possibly turn one of those down to reduce the harshness. I think it's how someone made the synth itself and not really necessary for eqing unless it's really really harsh.