Synthesis Engine
Synthesis Engine
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Regardless of the perceived loudness of the tone up to now, it will disappear by fading
out. Similar to the Attack segment, the Release time can be sensitive to the key-up
velocity.
As explained, the key velocities can influence the perceived loudness of the tone as well
as the speed of its start and demise. In addition, the Key Tracking parameters deter-
mine how much the key position influences both the levels and times of the envelope
segments.
In conclusion, an Envelope group can model quite a lot of dierent tonal processes with
varying degrees of realism. It can produce spiky impulses as well as long, complicated
and seemingly artificial contours. All parameters, but especially the timing are highly
precise and their sensitivities to the performing user can be carefully defined as well.
Finally, three more aspects are quite worth mentioning. Whereas the times of the first
two segments (Attack, Decay 1) are well defined by (finite) transitions, the remaining two
segments (Decay 2, Release) approach their destinations exponentially. This means, the
signal takes an asymptotical path towards a specific value, but actually never reaches it.
In order to define the speed of this infinite process by a particular time, the definition is
as following: When the signal drops from 100% towards zero (as described for the Gate
signal), aer the given time the signal will be at approximately 37% still. This relationship
may sound arbitrary or random, but actually reflects countless natural processes (like the
behavior of a plucked string).
Secondly and up to now, all three Envelope groups (A, B, C) have been described at once.
A major dierence of Envelope C as a global modulation source is, that its Breakpoint and
Sustain levels are bipolar. This renders Envelope C more versatile and can make tonal
evolutions even more complex.
At last, another note on the Release segment in the context of the modulation mecha-
nism. All segment times are represented as modulation target parameters, so they can be
influenced by the Macro Controls. And whereas the times of the first three segments can
be precisely tuned between zero and 16 seconds, the Release Time (target) parameter can
be further set to infinite, allowing the Release segment to „freeze“. This allows for the inte-
gration of a „Sustain Pedal“, modulating the Release time up to infinity while holding it.
In total, there are four envelope signals to be taken use of. Three of them are flexibly
definable, as provided by three parameter groups called Envelope A, B and C. Whereas
Envelopes A and B are applyable in the two branches (Oscillators and Shapers), Enve-
lope C can be used more globally for the modulations of pitches, cuto frequencies,
resonances or feedback levels. In addition, a non-parametric Gate signal is produced and
applied for feedback control and the decay of the Comb Filter.
The Gate signal is a very simple envelope that jumps to 100% intensity when a key
is pressed. When this key is released, the signal drops back to zero within a few
milliseconds.
The signals of the other three envelopes are way more advanced. Lots of parameters
define the behavior of each envelope, including variable sensitivities to the velocities and
pitches of played notes.
For a particular envelope (A, B or C), there are four consecutive segments defining the sig-
nal progression. When a key is pressed, the signal starts by rising from (usually) zero to the
peak level within the Attack time. The peak level can depend on the key-down velocity,
whereas the time can range between zero and 16 seconds and also can depend on the
key-down velocity (shortening it for higher velocities). The Attack curve is linear by default
but can be tweaked to get a concave or convex shape. With a concave shape it starts with
a smaller slope and gets steeper, with a convex shape it is the opposite. The time and
curve of the Attack segment determine the perceived sharpness of the beginning tone.
When the signal has reached the peak level, a new transition to the Breakpoint level
(between zero and the peak level) will begin. This segment will be active within the given
Decay 1 time (also between zero and 16 seconds). It will impact the early evolution of the
produced tone. The first two segments determine the start transients, which are import-
ant for the perceived character of a sound.
When the signal has reached the Breakpoint level, the Decay 2 segment will become
eective. Within a given time, the segment will exponentially approach the Sustain
level (between zero and the peak level as well). The Sustain level defines how much the
perceived tone will persist at a stationary level while holding the corresponding key. High
Sustain levels are typical for pad and organ sounds, for example. If the sustain level is low
or zero, a percussive tone character will emerge, with the Decay 2 time controlling if it
sounds shorter or longer. The sustain level will hold as long as the key remains pressed.
The final segment, called the Release phase will become eective as soon as the corre-
sponding key is released. Within a given time the signal approaches zero exponentially.
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