The Voltage-Controlled Filter; Emphasis - Moog MEMORYMOOG 345 Owner's And Service Manual

THE VOLTAGE-CONTROLLED
FILTER
O
The
job of the
FILTER
is
to
modify
the
signals
from
the
sound
sources (the
OSCILLATORS
and
the
NOISE SOURCE). The
FILTER
in
the
Memorymoog
is
the patented
Moog
24dB/octave lowpass
filter.
It*s
called a
lowpass
filter
because
it
filters
out
—
stops
—
high frequencies
from
getting
through and
lets
low frequencies
pass.
The
setting
of the
CUTOFF
control
(8.2)
determines
how many
high
frequencies
are
filtered
out and
how many
low
frequencies are
let
through.
All of the
modulation
voltage sources that
can
be applied to the
filter
affect
its
CUTOFF
frequency.
To
listen
to
the
effect
that changing the
CUTOFF
frequency has on the timber of the various wave-
shapes,
set
up
this
patch
starting
with
a
live
panel:
HEARING
WHAT CHANGING THE CUTOFF FREQUENCY DOES
o
OSCILLATORS
A
I//
WAVESHAPE
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f
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:
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PULSE WIDTH
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^„
waveshape:
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W::3M:'mi%k%¥MBB¥'iMti:i frequency
pulse
width
(%1"
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100
waveshape
# m #
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frequency pulse width
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EXPERIMENT WITH CHANGING
WAVESHAPES,
CHANGING
LEVELS,
CHANGING OCTAVES.
oniz]
VOLTAGE CONTROLLED
FILTER
]
KB track
• •
7/3 2/3
-5 5
2 8
10
2
^8
10
CUTOFF EMPHASIS
CONTOUR AMOUNT
700
1
1.5
1.4
f
3
5
1.4
f
3
400^1^3
800 ^\
1/^6
^\/^
800^\l/^6
100 6
200—
12
2
8
200
12
10^
\^9
20^/ ^18
-^/^
20^
\\l8
1MSEC
10
SEC 2
MSEC
20
SEC
10 2
MS
EC 20 SEC
attack DECAY SUSTAIN
RELEASE
• • •
•
-D-
-D-
-D-
—
Q"
return UNCONDITIONAL KEYBOARD RELEASE
TO ZERO CONTOUR FOLLOW
700
I
1.5
1.4
f
3
^\1//
1.4
2
3
800^X1
//6
100 6 200 12
2
8
200—
12
.0-;
\-»
ao-/
^,.
7^
20-^ \^18
1MSEC
10
SEC
2
MSEC
20
SEC
2
MSEC
20 SEC
ATTACK
DECAY
SUSTAIN RELEASE
VOLTAGE
CONTROLLED
AMPLIFIER
J
TURN CUTOFF FREQUENCY
SLOWLY, LISTENING TO THE
TONE OF EACH WAVEFORM.
LISTEN
TO THE EFFECT
THE CUTOFF
FREQUENCY
HAS
ON THE NOISE SOURCE.
Play a
low note on
the
keyboard. Slowly turn the
CUTOFF
control,
listening
to the
harmonics
being swept. You*lI notice
that
if
you play high notes and
turn the
CUTOFF
control
down
too
far
(counterclockwise to -3
or-
5)
you
won*t hear
any sound
at
all.
That's
because the
FILTER
CUTOFF
is
below
the frequencies of the note you're playing.
EMPHASIS
i
J
Turning
this control
up puts
z
resonant
peak
at
the
FILTER'S
CUTOFF
frequency.
When
the
setting
is
a
little
past
7,
the
FILTER
actually starts oscillating
on
its
own, becoming
another
sound
source.
Listen to
the
effect
of turning the
EMPHASIS
control
(see
diagram
on
the following page):
31