Oberheim OB 12 Operating Manual - page 29
OB 12
Z-Domain Synthesizer
149
•
[WAVE SELECT]: you can use these keys to activate/deactivate the waveform associated to
them. The LEDs above the keys display the status of the waveform according to the following
rule:
-
LED on: waveform present
-
LED off: waveform deactivated
•
[WIDTH]: this trimmer controls the pulse width of the square waveform. The trimmer can be
turned to the minimum or maximum setting to enrich the harmonic spectrum of the sound.
•
[SYNC]
(Synchronisation)
: this button activates (LED on) and/or deactivates (LED off) the
synchronisation of the waveform leaving Osc.2 with that generated by Osc.1. This means
that whenever the Osc.1 waveform returns to its starting point the Osc.2 waveform will also
be reset (or returned to its cycle start). As the diagram below shows, the result is a more
complex waveform:
If the synchronisation effect is not very noticeable, increase the first slider on the left
[OSC1
ð
OSC2] in the OSCILLATOR COMMON section.
•
[LFO1 DEPTH]: regulates the depth of the frequency modulation by the LFO1 (first low
frequency oscillator) on the pitch (with cyclic variation) of the Osc.2 signal, thus generating
vibrato effects. With the knob turned completely to the right, Osc.2 will be affected by the
maximum depth of LFO1 modulation. With the knob in central position, the oscillator will be
unaffected by the modulation, and when it is turned completely to the left, the modulation
depth will be at the maximum but with opposite phase to that obtained with the knob turned to
the right.
•
[FINE]: regulates the fine tuning of Osc.2 in a range of
±
50 hundredths of a semitone. When
the trimmer is in the central position, there is no change in the pitch.
•
[RANGE]: regulates the tuning of Osc.2 in a range of
±
24 semitones. When the trimmer is in
the central position, there is no change in the pitch.
The main feature of these two controls is that they put the second oscillator out of tune with
the first. This allows you to generate effects giving space to the sound, and harmonisation
between the two oscillators (if the difference in pitch is set, for example, at 5-7 semitones).
•
[PWM DEPTH]
(Pulse With Modulation Depth)
: this trimmer can be used to regulate the depth of
modulation of only the square waveform generated by Osc.2 by the source specified by
means of the button below the trimmer itself. This button allows selection of the following as
source of the modulating signal:
-
LFO1: the first low frequency oscillator