Discussion about the Korg PolySix synthesizer

Are the oscillators in tune in themselves and amongst each other and only the whole instrument too low?

Then check the +/- 5V on KLM-369/VR2 (the overall TUNE knob). If this is OK you might want to change R18 on KLM-369 to a lower value, e.g. 470K Ohm, to give it a wider range.

Good luck!

Johannes