I had the sam question and it's answered in on e of the posts in this 45 pages, but you don't have to wade through it all; here's the answer I got:fese wrote:There's one thing though I don't understand: the DCO switch in the pitch section. I know DCO usually stands for "digitally controlled oscillator", but frankly, I didn't hear any difference soundwise if it is active or not.
* DCO off in poly mode: free running oscillators. Further more, voices are randomly detuned slightly against each other so that when playing octaves, there is a slight beating.
* DCO on in poly mode: phase locking of voices to a virtual master oscillator. Voices have perfect tuning relative to each other.
* DCO on in mono/legato mode: if a note is triggered after the synth was silent, phases of osc1 and 2 are reset at note start (so this is similar to retrigger option in other synths)
* DCO on (all modes): perfect relative tuning of osc1 and 2. Thus, if the oscs are tuned exactly 0,1 or 2 octaves relative to each other, no beating will occur. Very important to achieve certain effects (e.g. a phase-locked sub osc, or creating new waveforms via e.g. ring mod)
* DCO off (all modes): slight pitch drift between osc1 and 2
Finally, note that a global pitch drift happens regardless of the DCO settings.

