Sequential PROPHET-600 - 7-1 OSCILLATOR A

7-1 OSCILLATOR A
OSC A is
an audio-frequency source always under
control of its
FREQUENCY knob,
the
keyboard, PITCH wheel,
and MASTER TUNE
knob. Its
frequency
(FREQJ
can
be
modulated by
the LFO-MOD and
POLY-MOD systems.
PULSE-WIDTH (PW) can also be
modulated
by the LFO-MOD
system.
4
5
B
S
10
FREQUENCY
V
YN
A
/\
SHAPE
n
10
PULSE
WIDTH
Figure
7-1
FREQUENCY knob: Adjusts
oscillator
pitch
in semitones, over a
four-octave range.
For basic "concert"
tuning, where the middle A on the
keyboard equals WO Hz, set the
FREQUENCY
knob two octaves above
"0"
on the dial. Exact
oscillator pitch is fine-
tuned
with the
MASTER
TUNE
knob.
SYNC switch: Forces OSC A to
follow
OSC
B in "hard"
synchronization. Depending on
the setting of the OSC A FREQUENCY
knob,
OSC A
will either lock to
harmonic
frequencies of OSC
B, or produce unusual timbres at the
next lower harmonic of OSC
B.
If
SYNC is on, and a
very narrow
or
wide pulse is selected for OSC A,
and
OSC B's
frequency is set much higher than OSC A,
the output from OSC A may disappear.
(Because the
pulse is not
given
a chance to discharge
before being re-synced, it
degenerates from audio to dc.)
Even
if
no
OSC
B waveshapes are switched on, SYNC still
operates, so the overall
pitch range of
the program will be determined by the OSC B FREQUENCY
knob
setting.
.
.
SYNC is used
in Factory Programs 17, 26, 76, and others.
SAWTOOTH
SHAPE switch: Enables full-level waveshape
containing
all
harmonics.
This basic
shape is often described as "brassy."
TRIANGLE
SHAPE switch: Enables full-level triangle
wave, containing little harmonic
energy, thus having a dull tone.
PULSE
SHAPE switch: Enables full-level
waveshape whose harmonic content, thus
timbre, depends on the setting of
the PULSE WIDTH knob.
If no
waveshape switch is on, OSC A will
have no
audio
output. If two or three
waveshape switches are on, all
waves are mixed at full level and supplied as OSC
A's
output to the MIXER.
CM600A 12/82
7-3