Clavia Nord Modular V3 User Manual download pdf (Page 200)

8. Synthesis basics: Subtractive synthesis NORD MODULAR V3.0

Page 192

2. By playing the keyboard: The keyboard is normally “hardwired” to the oscillator so that pressing dif-

ferent keys produce different pitches. In some cases this connection can be turned off, so that the

oscillator always plays the same pitch, regardless of which key is pressed. This can be done by deacti-

vating the Keyboard Tracking (KBT) function.

3. By modulation: Modulation allows you to make the pitch vary “automatically”. The most common

example is probably to use an LFO to make pitch go up and down, to create a vibrato. But you can

also put the pitch under envelope control, or make the pitch vary with your striking force (velocity).

The waveform of the oscillator affects its harmonic content and thereby its timbre. The three most com-

mon waveforms are sawtooth, pulse wave and triangle.

Looking at the shape of a waveform tells very little about how it sounds. Instead, there’s a better way to

show it, with a frequency

spectrum

. Let’s introduce some quick theory:

Mathematically, all waveforms can be considered as built from a number of

harmonics

, added together.

Each of the harmonics consists of a

sine wave

, the purest and simplest waveform there is (a sine wave has

no harmonics at all). In other words, if you add a number of sine waves together, each one with its own

pitch (frequency) and volume (amplitude), then you can build any waveform you like.

The lowest harmonic is called the

fundamental

. The fundamental determines the basic pitch of the sound.

If the fundamental has a frequency of 440Hz, we will perceive the entire sound as having a pitch of

440Hz.

Other harmonics are then added to the fundamental, called

overtones

. Normally the first overtone appears

at a frequency twice the fundamental (in our example 880 Hz). The next harmonic appears at a frequency

three times the fundamental (in our example 1320Hz) and so on.

In a spectral display of a waveform you can see the

frequency

(pitch) of each harmonic and its

amplitude

(level). This is done by drawing each harmonic as a line raising up from a horizontal scale. Each line’s

position on this scale indicates the harmonic’s frequency. The line furthest to the left is the fundamental,

the next is the first harmonic etc. To make life easier, one usually doesn’t label the horizontal scale with

frequency in Hz, but rather with the number of the harmonic. The height of each line represents the am-

plitude of each harmonic.

If you understand the principle, you also understand that if the harmonics with high numbers have a high

amplitude, the sound will be perceived as bright.

Let’s take a look at some common waveforms and their spectra. In the illustrations below, only some of

the first harmonics are displayed. In reality, waveforms like these have an infinite amount of harmonics.

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Clavia Nord Modular V3 User Manual Page 200

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