Modules And Methods For Generating Signals - M-Audio Wayoutware TimewARP 2600 User Manual

3.5

Modules and Methods for Generating Signals

How can you get access to the signals and processes we've just described, so that you can play with them on
your own?
Throughout the past century people have been noodling around with electronic ways of generating audio signals.
In particular, beginning in the 1960's, people such as Bob Moog, Don Buchla, and Alan R. Pearlman began to settle
on some ideas that have become almost standard for audio synthesis: independent, modular functions for signal
generation and signal processing, capable of being controlled not only by hand but also by signals of the same
kind as they generate.
This was the idea of voltage-controlled operation, and it was completely revolutionary. Using independent, modular
functions made it possible to change one attribute of a signal without necessarily affecting any other attribute; so
the craft of synthesis became the craft of constructing, and tuning, integrated configurations of modules.
The cables that connected modules were called patchcords, and so connecting modules together came to referred
to as patching them, and so, finally, any working configuration came to be called a patch.
Let's take a look at some modules that generate signals.
3.5.1 Oscillators
A device that repeats the same motion over and over is an oscillator. In audio synthesis, oscillators typically
produce very simple geometrical-pattern signals such as sine, triangle, pulse, and sawtooth waves, named simply
for what their time-domain graphs look like.
In an analog synthesizer, the underlying medium in motion is usually electrical pressure, or voltage. In a digital
synthesizer, the signal is actually generated as a sequence of calculated numbers. (Conventionally, these are
generated at the standard sampling rate for music CDs, 44.1KHz.) This does not become motion until, at the output
of the synthesizer, the number stream is converted to variations in voltage, and then amplified, and then used to
drive a loudspeaker. (A loudspeaker is a motor that moves back and forth instead of around and around.)
Because oscillator-generated signals are periodic, their spectral components always form a harmonic series.
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