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Chapter 13 Sculpture 265
Sculpture LFO waveforms
The LFO Waveform pop-up menus set dierent waveforms for the LFOs. The table below outlines
how these can aect your modulations.
Waveform Comments
Sine Ideal for constant, even, modulations.
Triangle Well-suited for vibrato eects.
Sawtooth Well-suited for helicopter and space gun sounds.
Intense modulations of the oscillator frequencies with
a negative (inverse) sawtooth wave lead to “bubbling”
sounds. Intense sawtooth modulations of lowpass
lter cuto and resonance create rhythmic eects. The
waveform can also be inverted, resulting in a dierent
start point for the modulation cycle.
Rectangle Use of the rectangular waves periodically switches
the LFO between two values. The Rectangle Unipolar
wave switches between a positive value and 0. The
Rectangle Bipolar wave switches between a positive
and a negative value set to the same amount above
and below 0.
An interesting eect can be achieved by modulating
pitch with a suitable modulation intensity that leads
to an interval of a fth. Choose the upper rectangular
wave to do this.
Sample & Hold
The two Sample & Hold (S & H) waveform settings
of the LFOs output random values. A random value
is selected at regular intervals, as dened by the LFO
rate. The S & H waveform steps between randomized
values (rapid switches between values). The S & H Lag
setting smooths the random waveform, resulting in
uid changes to values.
The term Sample & Hold refers to the procedure of
taking samples from a noise signal at regular intervals.
The values of these samples are then held until the
next sample is taken.
Tip: A random modulation of pitch leads to an eect
commonly referred to as a random pitch pattern
generator or sample and hold. Try using very high
notes, at very high rates and high intensities—you’ll
recognize this well-known eect from hundreds of
science ction movies.
Filtered Noise Can be used for chaotic modulations, but it is
principally of use in conjunction with the LFO
envelope function, where you would introduce a brief
modulation at some point in the note phase—for
example, to introduce breath in a brass emulation, or
to control an organ key click or piano hammer noise.
The random nature of the noise waveform means that
such modulations would vary slightly each time.