6
Synthesis Tutorial
Oscillators and Waveforms - The Mixer
The diagrams below show how these waveforms look on an
Oscilloscope and illustrate the relative levels of their harmonics.
Remember, it is the relative levels of the various harmonics present in
a waveform which determine the tone of the final sound.
In summary, the Oscillators generate Waveforms at a controllable
pitch. These Waveforms determine the initial character (Timbre) of the
sound.
Sine waves
These have just a single frequency. This waveform produces the
purest sound because it only has this single pitch (frequency).
Triangle waves
These contain only odd harmonics. The volume of each is the inverse
square of its position in the harmonic series. For example, the 5th har-
monic has a volume of 1/25th of the fundamental.
Sawtooth waves
These have a rich proportion of harmonics, containing all the harmon-
ics of the fundamental frequency. The volume of each harmonic is
inversley proportional to its position in the harmonic series.
Square waves
These only have only the odd harmonics present. These are at the same
volume as the odd harmonics in a sawtooth wave.
Noise waves
These have no fundamental frequency (and therefore no pitched ele-
ment). All frequencies are at the same volume. Because they have no
perceivable pitch, noise waves are often useful for creating sound effects
and percussion type sounds.
To extend the range of sounds that may be reproduced, a typical
Analogue synthesizer often has more than one Oscillator. By using
more than one Oscillator when creating a sound, it possible to achieve
very interesting harmonic mixes. It is also possible to slightly detune
individual Oscillators against each other which creates a very warm
‘fat’ sound. The K-Station has three independent Oscillators and a sep-
arate Noise Oscillator.
For flexibility, a mixer section is included so that the amplitude (volume
level) of each of the Oscillators may be adjusted independently and
mixed together to form a harmonically complex waveform.
As well as mixing together the individual Oscillators as shown in the
diagram above, the mixer section of the K-Station also allows the rela-
tive volume levels of the Noise Oscillator, Ring Mod and any external
sound source to be set.
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