Every 5th note sound muted

[SamZam]

I have a strange problem. On any patch, most audible on the basic program, every 5th note is muted, very low volume. The problem only occurs when Take 5 is operated in polyphonic mode (Unison not activated) and if the filter knob is not in clock 5 (maximum position). Easy to reproduce by pressing the same note on the keyboard, no matter how slow or fast, and every 5th is pretty much silent.

I've tried to calibrate oscillators, try another keyboard via midi, reinstall the firmware (2.0), reset globals - anything I can think of.

Does anybody have any ideas how to solve this? 

[SamZam]

Update: when I turn on Take 5 it actually works for a while, so maybe it's somehow caused by the device to warm up.

[kpatz]

Do a calibration when you hear it happening and see if that helps.

[SamZam]

Do a calibration when you hear it happening and see if that helps.

Thanks for the tip, but it didn't help. I also tried clearing calibration tables and recalibrating with no luck. I guess one of the voices is broken.