Technical data
EXERCISE
10:
KEYBOARD
CONTROL
OF
OSCILLATOR/FILTER
SECTIONS
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LBUDWIM
CCJIMI
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1.
Set
up
the
sound
chart
and
play
up
and
down
the
keyboard.
The
frequency
of
(both)
oscillators
is
being
controlled
by
the
keyboard.
Notice
that
the
OSCILLATORS
switch
is
in
the
NORM
(normal)
position.
2.
Place
the
OSCILLATORS
switch
in
the
DRONE
position.
Now
play
the
keyboard.
(No
pitch
change—pitch
"drones.")
The
NORM
position
of
the
OSCILLATORS
switch
places
both
OSCILLATOR
A
and
B
under
keyboard
control.
That
is,
it
connects
the
keyboard
to
the
frequency
control
inputs
of
the
oscillators.
The
DRONE
position
of
the
OSCILLATORS
switch
removes
the
oscillators
from
keyboard
control;
playing
the
keyboard
will
have
no
effect
on
oscillator
frequency.
Notice
that,
in
the
NORM
position,
the
levels
coming
from
the
keyboard
have
been
scaled
to
create
a
diatonic
(12
tone)
scale.
Other
scales
are
possible
with
"open
system"
manipulation
of
the
keyboard
output.
(See
OPEN
SYSTEM
section).
Also,
if
you
listen
carefully
you
will
hear
a
change
in
tone
color
when
the
OSCILLATORS
switch
is
in
the
DRONE
position,
even
though
the
pitch
is
not
changed.
Let's
explore
this
by
continuing
the
Exercise:
3.
Leave
the
OSCILLATORS
switch
in
the
DRONE
position.
4.
Alternately
play
the
lowest
and
highest
keys
on
the
keyboard.
The
pitch
doesn't
change,
but
the
timbre
of
the
sound
does.
Notice
that
the
FILTER
MODE
switch
is
presently
in
the
NORM
position.
5.
Place
the
FILTER
MODE
switch
in
the
FULL
position.
Now
the
difference
in
timbre
between
the
lowest
and
highest
keys
[s
more
pronounced.
The
preceding
shows
that
the
cutoff
frequency
of
the
FILTER
section
is
under
keyboard
control
in
both
the
NORM
and
FULL
positions
of
the
FILTER
MODE
switch.
In
the
NORM
position
only
half
of
the
keyboard
voltage
is
allowed
to
control
the
cutoff
frequency;
in
the
FULL
position
all
of
the
control
signal
from
the
keyboard
controls
the
cutoff
frequency.
Continue
the
Exercise:
6.
Leave
the
FILTER
MODE
switch
in
the
FULL
position;
Leave
the
OSCILLATORS
switch
in
the
DRONE
position.
7.
Place
the
GLIDE
control
to
switch
to
ON.
'5."
Switch
GLIDE
8.
Again,
play lowest
and
highest
keys
alternately.
Timbre
"glides"
between
keys
now.
This
indicates
that
the
GLIDE
control
affects
the
keyboard
signal.
Judging
from
some
gliding
pitch
sounds
that
are
heard
from
the
synthesizer,
one
might
think
that
the
GLIDE
control
does
something
to
the
oscillator—this
is
not
the
case.
The
GLIDE
control
slows
down
the
output
of
keyboard
changes;
the
keyboard
output
then
glides
between
voltage
steps
instead
of
jumping
between
them.
Since
we
have
been
using
the
keyboard
to
control
only
the
cutoff
frequency
of
the
FILTER,
use
of
the
GLIDE
control
causes
only
the
timbre
to
glide
between
keys.
If
we
choose
to
control
oscillator
frequency,
the
gliding
keyboard
control
signal
will
cause
the
pitch
of
the
oscillator
to
glide.
Let's
hear
it:
9.
Place
the
oscillators
under
keyboard
control
by
moving
the
OSCILLATORS
switch
to
the
NORM
position.
10.
Play
the
keyboard.
The
pitch
of
the
oscillators
glide
when
under
keyboard
control
and
GLIDE
is
used.
The
keyboard
signal
that
is
controlling
pitch
is
gliding.
11.
Remove
the
oscillators
from
keyboard
control
by
moving
the
OSCILLATORS
switch
to
DRONE.
12.
Play.
Oscillator
pitch
is
no
longer
under
keyboard
control,
but
the
filter
cutoff
frequency
is,
as
evidenced
by
the
gliding
tone
color
changes.
13.
Return
the
GLIDE
control
to
"0."
Now
play;
there
will
be
no
gliding
of
tone
color,
or
timbre.
39