INSTRUMENTS / GENERATORS
Sytrus - The Operator (Oscillator) Module
In FM Synthesis Oscillators are called 'Operators', this is because they can be used to modulate other operators.
The operator modules are central to the Sytrus synthesis engine as this section is used to define the operator shape and pitch. The module supports full articulation section (envelopes and mappings
of volume/pitch/phase, etc.)
NOTE: In Sytrus 1.5 and later, harmonics have been vastly enhanced and moved into their own tab. To learn more, see Working with the Harmonics Editor.
Shape Preview Window
The shape preview window shows the operator/oscillator shape after it is processed with the harmonics and other modifiers. There are 3 switches above the shape window (from left to right):
- Half - Uses only the first half of the shape phase in the sound generation.
- Even - Each odd phase of the shape is rendered
- Absolute - The shape values are made absolute
(only above the middle line).
The modifiers are a set of parameters which can help you in adjusting the
operator shape to suit your needs. Alt+click a modifier to reset it to its
- Shape (SH) - Allows to morph the shape to sine, triangle and pulse (via
the other modifiers you can also achieve saw and other shapes).
- Tension (TN) - Sets the tension (distortion) of the base operator shape.
- Skew (SK) - Allows you to "skew" the base operator shape.
- Sine Shaper (SN) - Applies a transform which is useful for certain patch
types (such as bells).
- Pre-Filter (FL) - Applies a smoothing (low-pass) filter to the shape. This
can reduce potential aliasing artifacts but makes the sound less bright.
- Noise (NS) - Mixes 'white' noise with the operator. At maximum it only plays white noise, in the middle its half white noise, half the operator.
This can be useful with plucked mode (which requires rich spectrum) and drum/percussion samples.
Pitch Offset & Multiplier
Here you can set the base pitch of the operator. Position the cursor over
a digit from either display and drag up/down.
- Frequency Offset allows you to adjust the
pitch as an absolute offset in Hz.
- Frequency Ratio is a multiplication over
the base pitch. The default value is 2. To increase the pitch with an octave,
multiply by 2
(x2, x4, x8, x16, etc). To decrease with an octave divide by 2 (x1, x0.5,
- Center - A DC offset removal.
- Declick - Applies a special filter
to avoid clicks when starting a voice (useful for operators with sharp attack).
- B.Limit - Band limits the waveform.
- Pluck - Plucked mode turns the operator
into a plucked string simulation unit. The unit basically starts with the original spectrum as set by all harmonics
and modifiers then a gradual "damping" occurs which filters that spectrum to a sine wave with the pitch value of the operator.
For this mode to work it is recommended to start with a spectrum rich operator (if you start with a simple sine there is no audible effect).
The damping amount is controlled via the DAMP articulation target (see articulation below). Note that an operator
in plucked mode can not be frequency modulated (FM) by other operators,so its FM row in the matrix will be disabled while plucked mode is on
(however ring modulation /RM/ is still available).
- Phase (PHS) - Sets the initial phase offset for the operator when a voice
is started (or global offset, depends on the next option).
- Global - Enable this option to use a "global" phase
for the operator in all voices (i.e. sync the phase between all voices for
- Volume (VOL) - Sets the operator volume.
The modulation levels in the matrix can not be automated, however this volume
property has the same effect for modulators and can be automated.
- Pitch Envelope/LFO Amount (PE) - This property
sets the range the pitch articulators operate with (the default value is
You can copy all the settings defining the oscillator and paste them to a
different operator by using the Copy/Paste Oscillator
Settings command in
the Options menu
The menu also contains the Reset Oscillator Settings in
case you need to quickly revert all oscillator settings to their default position.
The articulation section allows you to apply an envelope, LFO, map keys, velocity
or unison mode voices to a set of predefined properties. To see the full list
of envelopes/mapping in the articulation section and their meaning, please
check the envelope editor page.
The filter mode supports the following articulation targets (controlled parameters):
- Panning (PAN) - Sets the operator output
panning (graph bottom = left panning, graph top = right panning).
- Volume (VOL) - Sets the operator output volume
(graph bottom = no output, graph top = maximum output).
- Modulation Influence (MOD) - Defined the
amount of 'influence' other operators (as modulators) can have on the current
operator (graph bottom = no modulation, graph top = maximum modulation).
- Pitch Offset (PITCH) - Sets an offset to
the operator base pitch (graph bottom = -100% offset, graph top = +100% offset).
- Phase Offset (PHASE) - Sets an offset to
the operator phase (graph bottom = -100% offset, graph top = +100% offset).
If you vary the phase via the LFO articulation unit, the result is a
- Plucked Damping (DAMP) - This target has
effect only if the plucked strings mode is enabled for the operator. This
envelope/mappings set controls the plucked string dampening amount (graph
bottom = 100% dampening, graph top = no dampening).
- Oscillator Harmonics Editor (OSC) - A feature-rich harmonics editor and external sample analyzer lets you adjust the oscillator for every operator in Sytrus.