User Manual

14
Oscillator 1 and Oscillator 2 are the primary Subsequent 25 sound
sources. Each Oscillator generates four basic waveforms: triangle,
sawtooth, square, and pulse.
The triangle wave consists of odd-numbered harmonics only.
Its fundamental is very strong, and its overtones are very weak,
making it less harmonically complex than other waveforms. By
mixing a triangle from one Oscillator with a more complex wave
from the other, you can emphasize one particular harmonic without
mucking things up with unwanted overtones.
An unfiltered sawtooth wave is much brighter, because it contains
all the natural harmonics. As the harmonics ascend in frequency,
they grow weaker in amplitude. Sawtooth waves are useful for
synthesizing bass, simulating brass instruments, and more.
Although a pulse wave contains only odd-numbered harmonics, it
offers the most flexibility because you can change the balance of
those odd-numbered harmonics by changing its shape. Think of a
pulse-wave Oscillator as a switch you can turn off and on hundreds
or thousands of times per second. In a single pulse wave, the
“switch” is either on or off. Its pulse width is the proportion of the
wave that’s on, usually expressed as a percentage. A square wave is
simply a pulse wave with 50% pulse width, meaning that in a single
cycle, it is on half the time and off half the time. If its frequency
is 440Hz, that means it goes on and off 440 times every second, and the result you hear is the pitch
A above middle C. Every pulse width has its own characteristic sound, because each has a unique
harmonic structure, making a variety of basic timbres possible.
Unlike most synths, which simply switch between basic waveforms, Subsequent 25 allows you
to gradually change the Oscillator’s output from one waveform to another, so it can generate
something partway between a sawtooth and a square wave, for example. We refer to such controls as
continuously variable because there are no discrete steps between settings. In normal operation, either
the keyboard or external MIDI data controls Oscillator pitch. You can also apply the LFO or the Filter
Envelope to modulate Oscillator pitch and waveform.
OSCILLATOR CONTROLS
OCTAVE: This knob sets the pitch range for that Oscillator. Pitch range is expressed in feet, a
throwback to the age of pipe organs, when a pipe’s physical length determined its pitch. The
Subsequent 25 OCTAVE knobs cover four pitch ranges corresponding to four octaves. The lowest
setting is 16’, and the highest setting is 2’.
WAVE: This knob is used to control that Oscillator’s waveform from triangle to sawtooth to square to
narrow pulse wave. Turning the knob clockwise from the triangle to sawtooth position increases the
Oscillator’s harmonic content. Continuing to turn it to the square-wave position weakens and then
eliminates even-numbered harmonics while strengthening odd-numbered harmonics. Turning it from
the square to narrow-pulse position changes its harmonic content further by weakening the overtones
relative to the fundamental frequency.
FREQUENCY: This knob is used to fine-tune Oscillator 2’s pitch within its selected range. The knob’s
range is seven semitones higher or lower than its center position. At its center position, Oscillator 2 is
tuned to Oscillator 1. Turning it just slightly out of tune with Oscillator 1 can yield interesting detuned
or phasing effects.
OSCILLATORS