With FM Mode set to "Wave", the modulator is not always the selected wave.
Use these settings to verify:
- OSC 1 & 2 in Classic mode
- OSC 1 FM Mode "wave"
- OSC 1 & 2 with sine wave
- OSC Balance all the way to OSC 2
- OSC 1 transpose -48
- OSC 2 transpose +48
- Patch transpose -48
- dial in a small amount of FM (< 10%)
Now change the wave form of OSC 1 and hear how the FM of OSC 2 is affected:
- From 0 to 50% (Sawtooth): The modulator is always the selected wave (Sine, Tri, Complex 3-64)
- From 50% to 100% (Pulse): The modulator is always a rising (!) Sawtooth
Change OSC 1 to Wavetable and try the same as above, with similar result:
- From 0 to 50%: The modulator is always the same wave of the selected Wavetable
- From 50% to 100%: The modulator is always a rising Sawtooth
See this discussion:
Spectral Wave/Square Blend Workaround?