Oberheim OB 12, Руководство по эксплуатации

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OB 12
Z-Domain Synthesizer
8.2 EDIT OSCILLATOR 2
168
opposite signal phase originating from LFO1), 0 (no modulation), +50 (maximum modulation).
•
PWM DEPTH FROM LFO1
(Pulse Width Modulation Depth From LFO1, [PWM DEPTH] of OSCILLATOR 1
section assigned to LFO1)
: regulates the depth of modulation of the pulse width (PWM=Pulse With
Modulation) generated by Osc.1 by LFO1. The range of values is –50 (maximum modulation
with opposite phase), 0 (no modulation), +50 (maximum modulation).
•
PWM DEPTH FROM LFO2
(Pulse Width Modulation Depth From LFO2, [PWM DEPTH] of the OSC.1
section assigned to LFO2)
: regulates the depth of modulation of the pulse width generated by
Osc.1 by LFO2. The range of values is –50 (maximum modulation with opposite phase), 0 (no
modulation), +50 (maximum modulation).
•
PWM DEPTH FROM EG
(Pulse Width Modulation Depth From EG, [PWM DEPTH] of the OSC.1 section
assigned to EG)
: regulates the depth of modulation of the pulse width generated by Osc.1 by the
envelope generator (EG). The range of values is –50 (maximum modulation with envelope
reversed), 0 (no modulation), +50 (maximum modulation).
FREQUENCY MODULATION IN THE OB-12
The OSCILLATOR 1 section offers two types of frequency
modulation: that performed by the second oscillator (Osc.2)
and that carried out by the two low frequency oscillators (LFO1
and LFO2).
In the first case the frequencies of the modulant signal
(received from Osc.2) and the carrier (the Osc.1 signal) assume
almost the same value. This means that the spectrum content
of the modulated (carrier) signal is considerably enriched. In
this case, while the carrier determines the height and intensity
of the signal, the modulant establishes its timbre.
In case of modulation by the first or second LFO, the modulant
signal (received from the LFO) has much lower frequency
than the carrier signal. If the carrier is thus modulated with a
triangular waveform, a “vibrato” effect is produced, while
modulating with a square waveform provides a “trill” effect.
For sound generation, the OB-12 offers two oscillators having output waveforms which are already
complex (i.e. not the single triangular, pulse or ramp waves). This makes available two complex
signals which can be added together by means of the OSC.COMMON section. The combinations
of waveforms which can be obtained, generated by the second oscillator, are infinite in number,
and are displayed by setting the SCOPE parameter of the video page of the same name at
OSCILLATOR2 (see point 6.1).
To set this section of the generation chain, select option 4-OSCILLATOR 2 in the EDIT TIMBRE
MENU video page.
With regard to setting of the waveform, the display video pages relating to the three primitive
waveforms are identical to those already discussed for Osc.1, as follows: