Technical data
1.
Hold
down
any
key
on
the
keyboard.
The
tone
sounding
is
static
in
timbre;
the
cutoff
frequency
of
the
filter
is
not
being
moved.
2.
Move
the
CONTOUR
AMOUNT
control
to
"+5."
Now
hold
a
key
down.
The
timbre
is
dynamic
because
the
filter
cutoff
frequency
is
being
contoured
by
the
FILTER
CONTOUR
section.
You
could
get
the
same
effect
by
manually
moving
the
CUTOFF
control.
3.
Play.
Move
the
CONTOUR
AMOUNT
control
back
towards
"0"
to
progressively
attenuate, or
lessen
the
amount
of
contour.
The
CONTOUR
AMOUNT
control
lets
you
determine
the
amount
of
the
signal
from
the FILTER
CONTOUR
that
is
allowed
to
control
the
filter
cutoff
frequency.
As
you
probably
realize
from
looking
at
the
graphics,
the
CONTOUR
AMOUNT
control
also
attenuates
an
inverted
version
of
the
contour
signal.
(See
drawing
for
the
"-5"
side
of
the
CONTOUR
AMOUNT
control.)
For
now,
let's
look
at
the
positive
or
"normal"
side
of
the
CONTOUR
AMOUNT
control
to
avoid confusion.
Continue
the
exercise:
4.
Return
the
CONTOUR
AMOUNT
control
to
5.
Play.
Contouring
of
FILTER
section
is
heard.
6.
Place
the
ATTACK
control
in
the
FILTER
CONTOUR
to
"100"
(msec).
The
rise
time
of
the
contour
is
now
faster.
7.
Place
the
RELEASE
control
in
the
FILTER
CONTOUR
to
"100"
(msec).
The
release
time
of
the
contour
is
now
faster.
The
setting
on
the
ATTACK
control
determines
the
time
it
takes
the
FILTER
CONTOUR
to
raise
the
cutoff
frequency
of
the
filter
to
a
maximum.
The
CONTOUR
AMOUNT
determines
the
value
of
that
maximum.
The
RELEASE
control
determines
the
time
it
takes
the
FILTER
CONTOUR
to
return
the
cutoff
frequency
to
its
starting point.
Continue
the
exercise:
8.
Play
and
hold
a
note.
Notice
that
the
cutoff
frequency
is
sustained
at
a
maximum
as
long
as
you
hold
a
key.
Only
on
release
of
the
key
does
the
RELEASE
control
go
into
effect.
9.
Move
the
FILTER
SUSTAIN
switch
to
the
right.
Now
play
and
hold
a
key.
The
pattern
generated
by the
FILTER
CONTOUR
section
now
has
only
(wo
parts
whose
timing
is
determined
solely
by
the
ATTACK
and
RELEASE
controls
in
the
FILTER
CONTOUR
section.
10.
Play
and
hold
a
key.
Note
that
when
all
keys
are
released,
the
LOUDNESS
CONTOUR
RELEASE
control
is
still
operable
(note
hangs
on.)
This
shows
that
the
FILTER
SUSTAIN
switch
and
LOUDNESS
SUSTAIN
switch
work
indepen
dently.
11.
Place
the
RELEASE
switch
to
the
right.
Now
play
and
release
a
key.
Notice
that
the
final
release
will
now
be
abrupt.
The
RELEASE
switch
provides
immediate
release
of
both
the
LOUDNESS
CONTOUR
and
FILTER
CONTOUR
sections
when
placed
to
the
right.
(END
EXERCISE)
The
preceding
exercise
illustrates
that
the
LOUDNESS
CONTOUR
and
FILTER
CONTOUR
sections
are
identical
in
operation.
Each
is
a
controller.
The
LOUDNESS
CONTOUR
section
is
used
to
control
the
gain of
the
VCA
within
the
Multimoog.
The
FILTER
CONTOUR
is
used
to
control
the
cutoff
of
the
VCF
(FILTER
section).
On
the
Multimoog,
the
connection
of
the
LOUDNESS
CONTOUR
section
to
the
control
input
of
the
VCA
is
made
at
full
strength
internally
to
assure
the
best
signal-to-noise
ratio.
But the
connection
of
the
FILTER
CONTOUR
section
to
the
control
input
of
the
FILTER
has
the
CONTOUR
AMOUNT
control
which
allows
us
to
determine
the
amount
and
direction
the
cutoff
frequency
will
be
moved.
When
the
CONTOUR
AMOUNT
control
is
in
the
negative
region
(counterclockwise
from
"0"),
the
contour
generated
by
the
FILTER
CONTOUR
section
is
inverted
(turned
upside
down).
The
"-5"
position
then
represents
the
maximum
amount
of
this
inverted
signal.
Look
at
the
panel
graphics
to
get
an
idea
of
this
situation.
The
CONTOUR
AMOUNT
control
is
called
a
"reversible
attenuator;"
it
attenuates
the
amount
of
a
signal
as
it
is
moved
toward
"0"
for
either
normal
or
inverted
contours.
It
will
require
some
thought
to
understand
what
happens
when
you
use
a
negative
CONTOUR
AMOUNT
setting.
Everything
is
reversed
from
normal.
The
voltage
from
the
FILTER
CONTOUR
doesn't
start
at
"zero"—it
starts
from
a
maximum
vol
tage.
Instead
of
falling
to
"zero"
when
you
release,
the
voltage
will
rise
to
maximum.
The
following
diagrams
illustrates:
r
44