Moog-music Slim Phatty User Manual download pdf (Page 61)

Page 62

Slim Phatty User’s Manual - Appendices

Page 63

Slim Phatty User’s Manual - Appendices

The Oscillator is the starting point of Subtractive Synthesis, for it is here that the initial sound is created. The

oscillator creates electrical vibrations which function in a manner similar to the strings of a guitar; they create the

signal source that the rest of the system will use to modify and shape the sound. The key oscillator parameters

are pitch and waveform.

The pitch of the oscillator is primarily determined by the keyboard, which creates specic pitches based on an

equal-tempered scale (more about the keyboard later).

The waveform determines the harmonic richness of the audio signal. There are four basic waveforms common

to most synthesizers: sawtooth, square, triangle and sine.

The sawtooth wave is the richest sounding of the four waves. It contains all

of the harmonics, and has a bright, buzzy sound. Sawtooth waves are ideal

for brass and string sounds, bass sounds and rich accompaniments.

The square wave possesses a hollow sound compared to the sawtooth,

owing to the fact that it contains only odd harmonics. This hollow

characteristic is ideal for distinctive lead and sustained (pad) sounds.

An interesting aspect of the square wave is that the waveshape can be

changed to make the top and bottom parts asymmetrical, creating a pulse

wave. By changing the shape of the wave, new harmonics are introduced.

Pulse waves are ideal for creating clavinet-like sounds, but are also useful

for creating lush pads. Many synthesizers allow you to dynamically control

the shape, or ‘width’ of the pulse wave using modulation sources such as a

low frequency oscillator (LFO). This type of waveform control is known as

‘pulse width modulation’, or PWM.

The Subtractive Synthesis Model

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Moog-music Slim Phatty User Manual Page 61