Roland SH-09 - VCO Waveform Selection; Sub-Oscillator Function; Audio Mixer Functionality; VCF Functionality

Waveform Switch
This
rotary
switch
selects the
VCO
output
wave-
form,
providing
a basis pure
tone tor
the SH-09
to
shape and
process. The
basic
waveforms
.
include Noise
(a hiss
including
all
frequencies,
for
various sound
effects), Sawtooth wave
(a rich tone
for
strings, brass and full synthesizer
sounds),
Square
wave
(a tone very similar
to a clarinet
or
xylophone),
and Pulse
Width
Mod
(a
variable
Pulse
wave
sounding from
Square
wave
to very
nasal
in
tone).
The
Pulse
Width
Mod.
section
includes
a
three
position
Mode switch
including
Manual,
LFO
and
ENV
modulation
options,
and
a Pulse
Width
slider control
to
manually
adjust
Pulse
Width
or
the
amount of LFO
or ENV
modulation.
SUB
OSC
(Sub-Oscillator)
The
Sub-Oscillator
is
actually
a part of the VCO
and produces any one
of
three parallel
tones
including
a
Square wave
at
one or
two
octaves
below or
a Pulse wave
two
octaves
below the
VCO.
The Sub-Oscillator follows
the
VCO
pitch
in
all
particulars including LFO
and Bender modula-
tion.
Audio Mixer
Section
The
Audio Mixer mixes
the
VCO,
Sub-Oscillator
and
External Input signals in infinitely variable
pro-
portions before
sending
them
on
for
processing.
VCF
(Voltage
Controlled
Filter Section)
The VCF
is
used to
alter
the tone of the
Audio
Mix-
er
output by cutting or
boosting harmonics
in
that
sound. The
tone may
be
altered manually
or
automatically
through voltage
control
as a note
is
played. The
VCF
is a
24
dB/octave
Low Pass
filter
which
passes low
frequencies and
blocks high
fre-
quencies
Cutoff
Frequency
Control
The
Cutoff Frequency
Control
determines
how
much of
a
tone will
be filtered away
by the VCF.
In
its highest
position
the sound will
pass unchanged.
As it
is lowered
the sound will
become
progres-
sively
more mellow
until it
is filtered
away
to
silence
at
its
lowest
position.
This
control
acts as
a
starting
position for all
other
control functions
within
the VCF
section.
Resonance
Control
This
control emphasizes
the
frequencies
at the
point where
the Cutoff Frequency
begins
to
filter
a
sound. It is most often
used to emphasize
motion
within
the filter. At
its lowest level
it has no
effect
increasing
as the slider is
raised until it
begins
to
self-oscillate
near
the top of
the slider travel. In
this
position, the VCF
becomes
a separate sine wave
audio oscillator
which
is controlled
by all
the
Modulation
controls
within
the
VCF
section.
Envelope
Mode
Switch
This
three position
switch
determines the
source of
Envelope control
for
modulation of
the
VCF. In
the
/N^
(positive
Envelope)
mode,
the filter
cutoff
fre-
quency
will rise and
fall following
the
shape of the
Envelope. The
tone will
become brighter
and then
more mellow
once each time
the Envelope
Generator
is activated,
providing
the manual
Cutoff
Frequency control
is lowered
to make room
for
this
sweep.
In
the Kjf (Inverted
Envelope)
mode,
the filter
cutoff
frequency will fall
then rise
agaia following
a
mirror
image of
the Envelope
pattern
set The
tone
heard will
begin
bright
become
more mellow,
then
more
bright
agaia
Beginning
and ending
tone is
determined
by the position
of the VCF
Cutoff
slider.
The ENV
FOL'R
(envelope
follower)
position will
use the
changing
volume of
any
audio signal
appearing
at the EXT
AUDIO IN
jack
on the back
panel
to modulate
the VCF
cutoff
point in
a posi-
tive
direction. In
this
mode,
the filter
cutoff
will
rise
and fall
as
the
External Audio
Input
grows
louder
and
softer, providing
the
manual
Cutoff
Frequency
control
is lowered
to allow
for this
movement