Manual

Synthesizer Voice A-111-5 System A-100 DOEPFER

5 VCO Rectangle Pulsewidth

6a VCO Pulsewidth Modulation Source

6b VCO Pulsewidth Modulation Level

This group of elements is responsible for the additional

rectangle wave ("second" waveform) that can be added to

the waveform chosen by switch 4 . Control 5 is used

adjust the pulsewidth of the rectangle manually. In the

center position the pulsewidth is about 50% (provided that

no Pulsewidth Modulation is active). In the fully CCW (or

fully CW) position the rectangle wave is "off". This position

has to be chosen if only triangle or sawtooth is desired as

VCO waveform.

The pulsewidth adjusted by control 5 can be modulated by

means of the switch 6a and control 6b . This function is

called Pulsewidth Modulation (PWM) and used to obtain a

fatter sound (especially if a slow triangle is used for the

modulation) or for other sound effects.

Switch 6a is used to select the PWM source:

upper position: LFO2 = PWM source

center position: no internal PWM

lower position: ADSR = PWM source

Control 6b is used to adjust the intensity of the internal

pulsewidth modulation.

Pay attention that the rectangle waveform can be turned off

also by means of the PWM. If for example the manual

control 5 can is set to position 2 or 8, LFO2 (triangle) is

used as PMW source the rectangle wavform will disappear

periodically if the PWM level control 6b is increased

beyond a certain position. Same applies if ADSR is used but

in this case the disappearance is controlled by the ADSR

signal. If the rectangle waveform of LFO2 is chosen, the

VCO rectangle can be turned "off" and "on" periodically with

the frequency of LFO2.

In addition to the internal PW/PWM controlled by 5 , 6a

and 6b the control voltage applied to the "VCO PW" socket

2 modulates the pulsewidth of the VCO rectangle

waveform as described in chapter 3.