8
above. Gates are thus members of the general class of TIMING
signals; other timing signals are TRIGGERS. The Oberheim
2-voice synthesizer does not use trigger signals.
8. These three knobs set the constants
attack time
,
decay time
,
and
sustain voltage level
for ENV 2.
NOTE: as you can determine by examining the control voltage
select switches for the two VCO's and the VCF, ENV I can be
used to control VC0 1, and ENV 2 can be used to control VCO 2
andlor the VCF. in ordinary keyboard use, i.e. without special
effects, ENV I will be used only to control the VCA, and ENV 2
will be used only to control the VCF.
9. Each voice module contains a LOW-FREQUENCY OSCILLATOR. The
output of this oscillator is a sine wave and is available to
control the VCO's and/or the VCF through the voltage select
switches described under #lb, 2b, and 5. The actual frequency
of the LFO is set by the knob indicated here.
10. Normally the VCA is controlled by ENV 1 (see
NOTE
above).
In order to simplify the operation of the voice module while
learning, or whenever it is necessary to hear continuous sound,
this VCA BYPASS SWITCH can be moved to the
on
(right) position.
This disconnects ENV 1 from the VCA control input and leaves
the VCA permanently wide open so that signals pass through it
completely unaffected; in effect, the VCA is "bypassed." Moving
the switch to the left closes the VCA again and reinstates the
control voltage from ENV 1.
11. This light indicates the presence of a GATE signal (see #7
above) at the input to the two ENVELOPE GENERATORS. Press a
key; depending on the position of the 2ND-VOICE switch at the
left of the keyboard, one or both of the indicator lights will
go on.
NOTE: Even before hearing any sound from the synthesizer, you
can use these indicator lights to understand the function of
the VOLTAGE ASSIGNMENT SWITCHES (minisequencer #2). Move the
two left switches up to the SIH position, and press a key or
two; note that the lights do not now go on. Start the CLOCK
(minisequencer #5) and note that they go on and off regularly
at a rate that increases as the clock frequency increases.
