Waldorf Blofeld Keyboard - Manual (Page 91)

Sound Synthesis Basics
91 Blofeld User´s Manual
bow pulling the string slightly into one direction. At one
point, the string abruptly comes off the bow and swings
back to its original position. The bow is still moved and so
it catches the string again and the procedure is repeated.
The result is a waveform that looks like a sawtooth. The
same is true for a brass instrument. The string in this case
are the lips while the bow is the air. The lips are moved
by the air to a certain extent and abruptly move back to
their original position.
The Square Wave
The Square Wave is a special waveform generated by a
pulse waveform with 50% pulse width. This means that
the positive part of the waveform has equal length to the
negative part. The pulse waveform can have other pulse
widths as you will read later. For now, we´ll talk about the
square wave as a unique waveform. The square wave
consists of all odd harmonics in which the magnitude of
each harmonic descends by the factor of its position. This
means that the first harmonic has full magnitude, the third
harmonic has a third magnitude, the fifth harmonic has a
fifth magnitude and so on. The following picture shows
how the individual harmonics build up the sawtooth
wave:
Additive components of the square wave with 50% pulse
width
The square wave was thought as an abstraction of wind
instruments like a panflute or a recorder. They consist of a
1 3 5 7 9
Frequency
Magnitude
Time
Amplitude
+
=
1st Harmonic
Magnitude 1
5th Harmonic
Magnitude 1/5
7th Harmonic
Magnitude 1/7
Harmonics
+
+
+
.
.
11 13 15
3rd Harmonic
Magnitude 1/3