Technical data
In
the
previous
exercise,
the
OSCILLATORS
are
actually
not
turned
"off,"
but
simply
removed
from
the
audio
signal
path
so
we
don't
hear
them.
The
OSCILLATORS
generate
audio
signals
continuously-
even
when
we
choose
not
to
listen
to
them.
The
OSCILLATORS
switch
is
placed
in
the
OFF
position
because
we
don't
want
to
hear the
oscillators,
but
wish
to
hear
the
sound
produced
by the FILTER
section
alone.
FILTER/OSCILLATOR
SYNCHRONIZATION
Some
unusual
sounds
can
be
made
if
either/both
oscillators
and
the
FILTER
section
are
used
as
sound
sources
simultaneously.
When
this
is
done,
the
filter
can
be
"synchronized,"
or
locked
together
at
harmonic
intervals
(whole
number
multiples)
to
the
oscillator.
If
you
use
the
CUTOFF
control
to
tune
the
FILTER
section
to
sound
the
same
pitch
as
the
oscillator,
they
will
be
"synched"
at
the
fundamental.
The
OCTAVE
selector
will
cause
the
FILTER
CUTOFF
to
move
in
octaves
as
well
as
the
pitch
of
the
oscillator(s).
The
following
exercise
illustrates
synchronization
of
an
oscillator
and
the
FILTER
section:
EXERCISE
4:
OSCILLATOR/FILTER
SYNCHRONIZATION
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1.
Note
that
both
OSCILLATOR
B
and
the
FILTER
sections
are
used
as
sound
sources:
the
OSCILLATORS
switch
is
set
to
NORM,
and
the
FILTER
MODE
switch
is
to
TONE.
2.
Hold
down
a
key
in
the
middle
of
the
keyboard.
3.
Adjust
the
CUTOFF
control
until
growling
and
beating
disappear
(should
be
around
"O.")
4.
Play
the
keyboard.
The
OSCILLATOR
and
FILTER
sections
are
"synched"
at
the
fundamental.
When
the
pitch
of
the
FILTER
section
matches
the
pitch
of
the
OSCILLATOR
B
section
(CUTOFF
to
about
"O"),
and
both
are
used
as
sound
sources
as
shown
above,
they
are
synchronized
at
the
fundamental
frequency
of
the
oscillator.
Continue
the
exercise:
5.
The
FILTER
section
may
be
synchronized
at
a
harmonic
of
the
oscillator
frequency.
Slowly
move
the
CUTOFF
control
clockwise,
controlling
the
frequency
of
the
FILTER
section.
When
the
beats
disappear,
the
FILTER
section
is
synchronized
to
a
harmonic
of
the
oscillator
frequency.
6.
Try
different
CUTOFF
settings
that
"synch"
with
the
oscillator.
Play
the
keyboard.
7.
Move
the
DOUBLING
control
clockwise
away
from
"O."
This
provides
a
tone
two
octaves
lower
than
the
pitch of
OSCILLATOR
B.
You
should
now
hear
three
tones:
two
from
OSCILLATOR
B
and
one
from
the
FILTER
section.
(END
EXERCISE)
When
the
FILTER
section
is
in
the
TONE
mode,
it
becomes
another
sound
source.
It
may
be
used
in
conjunrtion
with
the
oscillators.
When
DOUBLING
is
added,
and
both
oscillators
are
used,
it
is
possible
to
have
four
tones
which
will
follow
the
keyboard
in
parallel.
The
oscillators
produce
three
and
the
filter
produces
the
fourth.
(If
you
tune
the
oscillators
to
a
strange
interval,
the
filter
may
become
confused
as
to
which
to
synch
to;
experiment and
you'll
find
the
useful
settings.)
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