Yes, I tried quality=5, too. But this did not change the wobble. To correct my first message: It's not really a wobble, it is a beat signal (I had to look for the translation).
At first I was confused, since I tried to add some sine waves for a simple sawtooth emulation, for a check (V1 = 4V @ 100Hz, V2 = 2V @ 200Hz, V3 = 1V @ 300Hz, V4 = 0,5V @ 400Hz, V5 = 0,25V @ 500Hz). It looked nice in the beginning. However, while running and adding some other stuff to the circuit the signal was slowly changing into a shaky line and then back to a kind of sawtooth again..