10.6

484Logic Pro Instruments
Logic Pro Sculpture LFO waveforms
The LFO Waveform pop-up menus set different waveforms for the LFOs. The table outlines
how these can affect your modulations.
Waveform Comments
Sine Ideal for constant, even, modulations.
Triangle Well-suited for vibrato effects.
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 filter
cutoff and resonance create rhythmic effects. The
waveform can also be inverted, resulting in a different
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 effect can be achieved by modulating
pitch with a suitable modulation intensity that leads
to an interval of a fifth. Choose the upper rectangular
wave to do this.
Sample & Hold The three Sample&Hold (S & H) waveform settings
of the LFOs output random values. A random value is
selected at regular intervals, as defined 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 fluid changes to values.
The S&H from CtrlA setting is controlled by the
CtrlA modulation source. For example, you could
assign aftertouch as the CtrlA source to trigger S & H
modulation of pitch.
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 effect
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 effect from hundreds of
science fiction 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.