Yamaha CS2x - Manual (Page 16)

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Oscillators, Filters, Amplifiers And Envelope Generators
Synthesizers rely on three distinct electronic components to imitate or “synthesize” the soundwaves of musical instrument voices as well
as create entirely new sounds. In traditional analog synthesis the fundamental source sound pitch is generated by an
oscillator, its tone
is created by a filter, and its volume is determined by an amplifier.
Another key component is known as the envelope generator (EG). An envelope generator determines how the pitch, filter or amplifier
behaves over time to create greater dynamics. The EG affects specific sound levels over time through “ADSR” stages, or Attack (initial
fade-in time), Decay (the time it takes to reach the Sustain level), Sustain (the specified level while a key is held) and Release (the time
it takes for the level to reach zero after releasing the key).
The oscillator generates sound wave vibrations at controllable speeds, or frequencies
(“cycles per second”) to create pitch. A frequency cycle is the time it takes for a sound
wave to go from its zero position (represented by the dotted line in the illustration) to
its point of maximum peak (top), back past zero to its maximum trough (bottom), and
finally back to zero. Frequencies are measured in “Hertz” (Hz), where one cycle per
second is equal to one Hz. Synthesizer oscillators usually offer a range of frequencies
between 20 Hz and 20kHz to generate pitch, which is the range of the “audio
spectrum” that most human beings can hear. They also usually offer various types of
sound waveforms with specific shapes and sound characteristics, such as sine,
sawtooth, square, pulse and other waves. Oscillators in the CS2x, unlike traditional
analog synthesizers, consist of complete AWM2-type sampled “waveforms” with
stable tuning. You can use the PEG (Pitch Envelope Generator) parameters to directly
control the critical pitch characteristics over time.
Musical instrument sounds are made up of the basic tone that we clearly distinguish
with our ears plus additional harmonics, or overtones which exist at each octave
above the basic tone, but that we cannot distinctly hear. The filter provides control
over these harmonics. By manipulating the filter’s cutoff frequency (which determines
where to delete, or cut off the overtones) and resonance settings, you can thus
determine the tone. With the CS2x, you can use the FEG (Filter Envelope Generator)
parameters to directly control the critical tone characteristics over time, as well as
control cutoff, resonance and other parameters to shape the tone.
An amplifier controls the volume of the tone. The CS2x has an AEG (Amplitude
Envelope Generator) which lets you control various volume characteristics over time.
Amplifier Filter Oscillator
Controls Volume Characteristics Over Time Controls Pitch Characteristics Over Time Controls Tone Characteristics Over Time
Amplitude Envelope Generator Pitch Envelope Generator Filter Envelope Generator
1 octave
1 octave
1 cycle per second = 1 Hz
* Doubling the frequency increases pitch by one octave
** Halving the frequency decreases pitch by one octave
OSCILLATOR
Frequencies generate the pitch of specific notes
A2 = 220Hz
A3 = 440Hz
A4 = 880Hz
* **
* **
FILTER
More harmonics
creates a
brighter tone
Less harmonics
creates a
darker tone
Harmonics
Basic tone
The number of harmonics can be
increased and decreased
AMPLIFIER
A tone’s volume level can be controlled
over time
Lower volume level
Higher volume level
cCS2x_Basic 12/10/98 5:25 PM Page 16