User Manual

22
MODULATION
Controlling modulation (abbreviated as MOD) is an important
aspect of programming and playing synthesizers. When
you modulate a synthesizer’s audio signal, you are changing
something about the way it sounds. When you modulate a
control signal, you are changing something about its effect on
whatever it’s controlling. Synthesizers route their control signals
from modulation sources to modulation destinations. On the
Subsequent 37, a changing control signal can modulate pitch, lter
cutoff, waveform shape, VCA level, LFO rate, noise level, EG time,
and a variety of additional destinations available via the PRESET
EDIT MENU.
The Subsequent 37 has two modulation busses labeled MOD 1 and
MOD 2. They are nearly identical except that, by default, the overall
depth of MOD 1 is determined by the MODULATION wheel. You can
access and edit this, and other extended modulation parameters by
pressing the CONTROLLERS button.
Low-frequency oscillators generate repeating waveforms in the
sub-audio frequency range. The Subsequent 37’s LFOs also have a
HI RANGE button, which allows the LFOs to generate frequencies
well into the audio range as well. At sub-audio rates, the LFOs are
useful for generating repeating effects. At audio rates, the LFOs add
harmonic complexity to their destinations.
When an LFO modulates an oscillator’s frequency, the oscillator’s
pitch follows the shape of the modulating waveform. If the
LFO’s output is a triangle wave, the pitch rises and falls at a regular rate. At the proper rate and
depth, this type of modulation is called vibrato. Many performers rely on vibrato to add expression
to their performances. A violinist or guitarist employs vibrato with a shaking motion of the hand as it
applies pressure to the string. A singer subtly uctuates their vocal pitch. A synthesist uses an LFO
to modulate an oscillator’s frequency. The LFO RATE knob controls the rate of modulation, and the
MODULATION wheel controls its depth.
MODULATION CONTROLS
LFO RATE
By default, the LFO RATE knob varies the low-frequency oscillator’s modulation rate from 0.1Hz (one cycle
every 10 seconds) to 100Hz (100 cycles per second). This can be multiplied 10x by using the HI RANGE button.
SOURCE
Use this knob to specify whether the modulation source is one of 5 LFO waveforms, the lter envelope,
or a programmed source. At its most counterclockwise position, the LFO generates a triangle wave,
which is particularly useful for vibrato. Turning the knob clockwise, the next position generates a
square wave, which is useful for performing trills and tremolo effects. The next two positions generate
sawtooth and ramp (reverse sawtooth) waves. Applied to pitch, sawtooth-wave modulation is useful
for simulating alarms, ray guns, and other ascending and descending effects.The fth position uses
sample-and-hold as a modulation source. Think of sample-and-hold as a source of random control
signals. (Think 1970’s Hollywood sound effects of a computer “thinking”.)
When SOURCE is set to F. EG/PGM, the LFO is bypassed and by default, the lter’s envelope settings
are used as a source of modulation. A variety of additional modulation sources are also available to
you by pressing the CONTROLLERS button. To learn more about the MOD CONTROLLERS menu, go
to page 50.