12. Synthesis basics: Additive synthesis
NORD MODULAR G2 V1.1
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Additive synthesis basically is the opposite of Subtractive synthesis. Instead of using waveforms with rich
harmonic content, such as sawtooth and pulse waves, and attenuating and amplifying different parts of
the harmonics with filters, you build your waveforms by adding together a number of sine waves. This is
how tonewheel organs work, for example.
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To show the basic principle of additive synthesis, lets create a “rough” triangle wave out of several sine
waves. The triangle wave does not have very strong harmonics. Furthermore they only appear at odd har-
monic numbers. The first fact makes the tone pure, a bit like a flute, and the second fact gives the sound
a slightly “hollow” character. Since a “perfect” triangle wave consists of an infinite number of sine waves,
it’s not practically possible to get a perfect result, but we can get pretty close. In the example below, we
use six different sine waves to create our triangle wave. Note that the levels of the different oscillator har-
monics is only schematic. The resulting waveform shape is also a rough estimation:
Why should you use additive synthesis to create complex waveforms, when you can easily get similar or
even better results using subtractive synthesis, you may ask. Here is an important difference:
• With additive synthesis, you have total control over each single harmonic in the waveform. This makes
it possible to really tailor-make your waveform. With subtractive synthesis, you can only control seg-
ments of the harmonic content.
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Osc 1
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