Hi!
I have a strange problem that started occurring recently out of nothing.
When turning the mixer knob the pitch changes; a semitone up when turned to the left (DDS1) and a semitone down when turned to the right (DDS2).
This happens on every patch, including the init-patch (shit+manual).
Does anybody know how to fix this? 
I have the xos_v1.6 firmware on my UDO.
Best regards Petter
Because the shift follows the mixer control and is exactly about a semitone in opposite directions (DDS1 versus DDS2), I’d first separate a control-voltage/mixer-routing problem from oscillator tuning. With the init patch, tune one oscillator to a known A=440 reference and monitor it alone; move the mixer knob slowly. If that isolated VCO’s pitch changes, check the mixer’s VC routing/normalled CV and any modulation assignment (including MIDI pitch-bend), rather than the waveform level. If the isolated VCOs stay fixed but the combined sound shifts, look for a digital detune/voice setting or calibration issue. Also unplug MIDI/USB and repeat with pitch-bend centred: a stuck or mis-scaled MIDI pitch-bend can move pitch, although the opposite DDS1/DDS2 behaviour points more strongly to routing. Verify against the known A=440/patch-tune reference before recalibrating or changing firmware. For a quick refresher on hearing intervals and tuning checks, listening and frequency reference.