Instruments and Effects

626 Appendix Synthesizer Basics
Classic synthesizer literature encourages the use of the triangular wave for the creation
of flute-like sounds. In the age of sampling, however, it’s pretty hard to sell a triangular
wave as a flute sound to anyone.
The screenshot above shows a rectangular wave. The rectangular wave contains all odd
harmonics, the amplitudes of which decrease proportionately with their number. The
pulse width can be set to any value and serves as a modulation address.
Classic synthesizer literature likens the rectangular wave to the sound of a clarinet, as
the clarinet doesn’t feature any even harmonics in a certain frequency range either.
Envelopes
What does the term envelope mean in this context? In the image, you see an
oscillogram of a percussive tone. It’s easy to see how the level rises immediately the
top of its range, and how it decays. If you drew a line surrounding the upper half of the
oscillogram, you could call it the envelope of the sound—a graphic displaying the level
as a function of time. It’s the job of the envelope generator to set the shape of the
envelope.
The screenshot shows a recording of an ES1 sound created with these ADSR (attack
time, decay time, sustain level, and release time) parameter settings: attack as short as
possible, medium value for decay, zero for sustain, medium value for release.