User Manual

21
Controlling modulation (abbreviated as mod) is an important
aspect of programming and playing synthesizers. When you
modulate a synth’s audio signal, you’re changing something about
the way it sounds. When you modulate a control signal, you’re
changing something about its effect on whatever it’s controlling.
Synthesizers route their control signals from modulation sources
to modulation destinations. On your Subsequent 25, a changing
control signal can modulate pitch, filter cutoff, and waveform
shape. You control the modulation signal’s depth using the MOD
wheel immediately to the left of the keyboard.
All LFOs generate repeating waveforms in the sub-audio range.
The Subsequent 25 LFO has an extended range capable of
generating audio frequencies as well. At sub-audio rates, the LFO
is useful for generating repeating effects. At audio rates, the LFO
adds harmonic complexity to its destination.
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 fluctuates vocal pitch. A synthesist uses an LFO to
modulate Oscillator frequency. The LFO RATE knob controls the
rate of modulation, and the mod wheel controls its depth.
MODULATION CONTROLS
LFO RATE: By default, this knob varies the low-frequency Oscillator’s modulation rate from 0.1Hz (one
cycle every 10 seconds) to 100Hz (100 cycles per second). You can change this range in Shift mode
(see Hidden Parameters on page 30).
SOURCE: This knob specifies whether the mod source is the LFO or the Filter Envelope, as well as
the LFO waveform. At its 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 fifth position uses sample-and-hold as a mod source. Without going into a lot of technical
explanation, think of sample-and-hold as a source of random control signals.
The SOURCE knob’s most clockwise position, labeled FILTER EG, bypasses the LFO and routes the
Filter Envelope to the modulation destinations, which are determined by the settings of the PITCH
AMT, FILTER AMT, and WAVE AMT knobs below.
PITCH AMT: This knob specifies the depth of pitch variation applied to the Oscillators when the MOD
wheel is engaged. If the mod source is the Filter Envelope, you can control changes in pitch using the
Envelope’s Attack, Decay, Sustain, and Release settings.
MODULATION