ncrement (our overall phase increment) is so much more negative
on the current sample than the previous one that the phase actually backs up.  (This is confusing to analyze because at this point in
the curve, the feedback is already holding the phase back, so we need to reach a point where the increase in the backup overwhelms the
increment on that sample, thereby backing up the overall phase beyond its previous held back value).
So the modulator phase backs into the
less negative part of the sine curve: ou