Length
The maximum duration of the envelope. The mean-
ing depends on the rate knob and the sync switch. If
sync is disabled and rate set to center, the maximum
duration is given in seconds.
Velocity
With the Velocity knob, the envelope amount can
be varied according to the velocity of the MIDI key
pressed. At default center position, the velocity has
no effect. Set to negative values, low velocities will
have a stronger effect than high velocities. Set to pos-
itive values, higher velocities increasing the envelope
amount.
Making envelope amounts velocity-dependent is par-
ticularly important for FM sounds. Low velocities typ-
ically correspond to low envelope amounts (resulting
in a soft sound), while high velocities typically corre-
spond to high envelope amounts (causing a brighter,
more aggressive sound).
Keytrack
The key track knob allows to make the envelope rate
dependent on the MIDI key number pressed. Usually
key tracking is set to zero, so the MIDI key number
has no effect on the envelope. The higher the key track
value, the shorter the envelope when pressing higher
keys. The purpose of key tracking is to imitate the
behavior of acoustic instruments such as the guitar —
high notes on the guitar decay more quickly than low
notes.
Key tracking requires the sync switch to be turned
off, otherwise it has no effect.
4.13 LFOs
Using oscillators, the filter and envelopes, it is pos-
sible to control the basic properties of a sound, such
as timbre, volume and pitch. For bass and percussive
sounds this may be enough to get good results, but
for pad or lead type sounds, the sustain stage can still
sound dull. This is because the pitch, filter cutoff and
volume are steady in this stage and do not change.
This is where LFOs (low frequency oscillators) come
into play. LFOs work similar to ordinary oscillators,
and usually generate a periodic signal using similar
waveforms (see fig. 4.10). LFOs are inaudible, how-
ever, their only purpose is to continually change one
or more aspects of the sound. The most typical ap-
plications are modulating the volume, cutoff or pitch,
resulting in a vibrato or tremolo effect. Dune’s three
LFOs are much more capable than that, however, as
almost any sound parameter can be used as a modu-
lation destination. Additionally, LFOs can modulate
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DUNE 2 User’s Manual
Summary of Contents for DUNE 2
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