Korg SDD-3000 Owner's Manual page 16

Natural Echoes
The SDD-3000 normally produces crisp, clean echoes that are very desirable in most situations.
Sometimes, however, it is preferable to have echoes where the highs die off more quickly than the lows, as they do in a
large room. Other times, 'pipe' echoes with no bass or extreme highs may be needed. All of these effects, and more, can
be created through proper use of the HIGH & LOW Filters.
Echoes with Pitch Shift
Of course, the Delay time of an echo program can be modulated just like a flange or chorus. This produces a pitch-
shitting effect that is not a true pitch transposer, but is still useful for certain special effects. The Square and Envelope
Follower WAVEFORMS are most commonly used to modulate echoes, since the Square waveform w ill provide the
most consistent and usable effect (especially at low INTENSITY settings), while the Envelope Follower will produce a
predictable variation that interacts with playing style in Interesting ways.