Doepfer A-111-1 High End VCO - Manual (Page 3)

doepfer System A - 100 VCO 2 A-111
3
3. Basics
3.1 Waveforms
Module A-111 puts out four waveforms simulta-
neously. All these signals have the same pitch, since
all are controlled by the same CVs at inputs ! and " .
Sawtooth
The VCO’s sawtooth waveform is available at output
/
. It has a ‘cutting’ sound, rich in overtones. All the
harmonics of the fundamental are present, with a
linear reduction in intensity as the harmonic series
progresses - so that the second harmonic is half as
strong, the third is one third, the fourth a quarter, etc.
(see Fig. 1).
Sawtooth waves are ideal for synthesizing sounds
which are rich in harmonics, such as percussion, brass
or vocal timbres, and as the carrier input to a vocoder.
Pulse wave
The VCO produces a square / rectangle wave at
output =. You can alter its pulse width (see Fig. 2) by
hand or by voltage control (pulse width modulation
or PWM for short).
Fig. 1: Harmonic spectrum of a sawtooth
A symmetrical pulse wave (ie. an exact square
wave, with a pulse width of 50%) has only odd harmo-
nics of its fundamental (see Fig. 3) and produces a
typically hollow sound.
Fig. 2: Rectangle waves with different pulse widths
f
1
f
2
f
3
f
4
f
5
f
6
f
7
f
8
f f
9
Harmonics ➨
0%
100%
1/f 1/f
a b
c