Yamaha CS-80 - Velocity Sensitivity; Pressure Sensitivity

SECTION
V
-
UNDERSTANDING
SYNTHESISERS
4
i
40
This
section
first deals
with
several
basic
conceptual
questions
about
synthesizers.
While
we
have
distilled
the
information
as much
as
possible,
some
topics
have
philosophical
or complex
origins
that
do not
lend them-
selves
to simple
explanations.
The
balance
of the
section
provides
an
overview
of how
the
CS-80
operates,
much
of
which
can
also
apply
to
other
synthesizers.
What is a Synthesizer
A
synthesizer
is
an
audio
processor
that has
a built-
in
sound
generator
(oscillator),
and
that
alters
the
envelope
of the
sound with
voltage
controlled
circuitry.
Synthesizers
can
produce
familiar
sounds and
serve
as
musical
instruments,
or they
can
create many
unique
sounds
and
effects
of their
own.
The
synthesizer
oper-
ates by
creating
each basic
element
of sound
and
then
providing
you
with
separate
controls
for
each
element.
You
don't
have
to use all
the many
controls
on
the
synthesizer
to
create
a
complete sound.
In
fact,
often
only
a
handful
of the
available
controls
need
be
used,
depending
on the
sound
you
wish
to achieve.
The Difference
Between
Synthesizers
&
Electric
Organs
An
electric
organ
offers
a wide
variety
of preset
sounds
at
the
touch
of a finger.
Synthesizers
usually
offer
no presets,
or very
few
of them,
instead
pro-
viding
an
infinite
variety
of
adjustable
sounds.
The
CS-50,
CS-60
and CS-80
offer
many
presets
and
infinitely
adjustable
sounds
as
well.
Organs
utilize
different
means
to
generate
sound
than
do synthesizers.
Because
of this,
most
organs
are
polyphonic,
meaning
that
you can
play many
notes
simultaneously,
whereas
most
conventional
synthesizers
allow
you
to
play
only
one
note
at a time. The
CS-
Synthesizers,
however,
incorporate
additional
circuitry
that
allows you
to play
several
notes
at
a
time
(4 on
the
CS-50
and
8 on the
CS-60
and
CS-80).
Why Use
a
Synthesizer
Many
of the
sounds
that
can
be
created
with
a
synthesizer
would
be either
Impossible
or highly
impractical
to
create
with
acoustic
instruments.
Also,
the
synthesizer
can
give
you common
acoustical
sounds
with
much
greater
convenience
than
would
otherwise
be
possible. For
instance,
you
can
adjust
the
controls
to "stretch"
a
common
instrument,
like
gradually
transforming
a
piccolo
to a Bass flute,
or
even
to
a
20'
long
flute. If
there
were
such
a thing.
Similarly,
the
synthesizer
allows
Instant
or
gradual
transitions
from
the
sound
of
one
instrument
to
another.
The Elements
of
a
Synthesizer
One
section,
the
VCO,
establishes the
pitch
or
frequency
of the
note,
as well
as the
basic tone
(timbre).
Another
section,
the VCF,
shapes
the tone
or
emphasizes
portions
of
it. Another
section,
the
VGA,
affects
the
loudness
of the
notes. Either
the VCF,
the
VCA,
or
both
may
be
used
to "turn
on" and
"turn
off"
the sound
in
a controlled
pattern, forming
the
notes
as
you play
the
keyboard. The
control
that
forms
the notes
is
provided
by Envelope
Generators
(EG),
one for
the
VCA
and
one for the VCF.
The
synthesizer
also
houses
many
other
functions
to
modify
the
basic
sounds
for
a variety
of effects.
Yamaha
CS-series
synthesizers,
because
they
are
polyphonic,
are actually
equipped
with
several
VCO's,
VCF's,
VGA's
and
EC's:
16
sets
on the
GS-80 for
creating
each
of the
8
notes
times
2 voices
that
can
be
played
simultaneously.
Why
Voltage
Controlled
Circuits
are
used in
Synthesizers
& How They
Work
You
can
set up
voltage
controlled
circuits
to
make
changes
automatically.
Suppose
you have
a sub
oscillator
that
produces
a
continuously
changing
voltage
(AG),
such
as the slow
sine
wave from
the
CS-80's
Sub
Oscillator. If
you apply
that voltage
to
the
control input
of
a
Voltage
Controlled
Amplifier,
the
sound
passing
through
that
amplifier
will
go
up
and
down in
level—
creating
a tremolo
effect.
(This
is
exactly
what happens
when
you move
down
the
VCA
lever
In
the
Sub
OscillatorSection.)
At this
point
you
are listening
to one
sound
source
that is
being
modulated
or controlled
by
something
else,
a sine
wave. If
you Increase
the SPEED
of the
Sub
Oscillator,
the
rapid
changes
in control
voltage
will
make
the sound
level
change
so fast that
beating
occurs,
producing
secondary
tones.
You
can
also
adjust
a
voltage
controlled
circuit
manually.
If
you wish,
just
like
any
conventionally
controlled
circuit. For
example,
you might
achieve
the
same
slow-speed
tremolo
effect by
continuously mov-
ing
a
Volume
control
up and
down, If
you had
the
fingers
free
to
do
it.
However,
you
could
not
possibly
move
that
volume
control
fast
enough
or smoothly
enough
by
hand
to
produce
secondary
tones. Thus,
voltage
controlled
circuits
enable
you
to
do things
that
could
not
be
readily
accomplished
with
purely
manually
controlled
circuits.
Amplifiers
(VGA's)
are
not
the only
voltage
con-
trolled
circuits in
a
synthesizer;
filters
and
oscillators
may
also
be voltage
controlled.
In all
Instances,
the
amount
of
change
In
the
sound
is proportional
to
the
voltage
applied
to
the control circuit. The same sine-
wave
voltage from the Sub Oscillator that
created
tremolo
in
the
VCA when applied
to
the control
in-
put
of
a
VCF
would create
wah-wah,
or
when
applied
to a
VCO
would
create
vibrato.
It
is
not
at all important for a player to understand
about
voltages and
control circuits to program and
play
the
GS-80.
When
you set the
controls and
levers
so
the
sound
Is "right,"
you are probably adjusting control
voltages.