Doepfer A-146 LFO 2 (variable Waveform) - Manual (Page 5)

doepfer System A - 100 LFO 2 A-146
5
• Variable pulse width
In using the square wave for AM or FM in the audio
range, it’s possible to control the timbre by adju-
sting the pulse width, because the amount of over-
tones (and sidebands) present is directly related to
the width of the pulse.
The A-146’s pulse width control also comes in
useful when using the LFO as a trigger or gate
generator for repeated sequences. The patch in
Fig. 3 is an example: the envelope (set to a dura-
tion t
G,
which is shorter than the LFO’s half-cycle),
gives the rhythm a more percussive feel. Whereas
with the A-145, an extra A-162 trigger delay module
would have to be used to adjust the gate duration
(Delay = 0, Length =...) to t
G
, that’s not the case
with the A-146: you simply have to adjust the pulse
width.
• Positive square wave output
This output has the useful function of being able,
unlike a normal positive/negative square wave, to
create pitched repeats which stay in tune.
Fig. 3: Producing gate pulses of variable duration
In Fig. 4 on page 6, the pitch of a VCO is controlled by
a CV from a keyboard, but also from the square wave
output of the A-146, via input CV2. The voltage at CV2
is set with the attenuator to exactly 1 volt.
A-145 A-162 ADSR
t
G
t
G
A-146 ADSR
t
G
t
G