Yamaha CS-5 Owner's Manual page 5

number
of
vibrations,
such
as 2-fold, 3-fold,
and
so
oil. It
is
seen
that the
waveform
will
gradually
come
to
resemble
a
saVk-tooth
waveform,
in addition
to
this,
it is
apparent
that
this
sawtooth waveform
has
a
cycle similar
to that
of
the
sine
wave
that has
been
used
as
the
basis.
The
sine
wave
with
the basic cycle
is
referred
to
as
the fundamental and
the
sine
waves
of
harmonic
overtones
as
the harmonics.
In the case of
musical instruments,
the
way
in
which harmonics
are
contained
in
sounds
will
depend on
the
arrangement
by which sounds
are
generated.
When we
discuss the
difference
in
tones (waveforms),
it is
the
same
as
dis-
cussing
what
kind of harmonics
the
sounds
contain.
Accordingly, one
can express
the three elements of
sound
in
another manner,
that
is,
as
1)
pitch. 2) the
manner
in
which harmonics
are
contained
(harmonic
structure)
and
3)
volume.
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WAVE
leve\
Ampl;tu<je
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A
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STRUCTURE
OF THE SYNTH
ESIZEft
In
the synthesizer,
sounds
are synthesized by
electronically effecting
control
on
the four properties
of
sound
(the three elements of sound
plus the
envelope), dividing
it
into
4
blocks.
Control of
pitch
is
effected
by
the
VCO.
that of
harmonic spectrum by
the
VCF,
that of volume
by
the
VCA
and
that
of envelope by
the
EG
(envelope
generator).
The
following describes the functions
of
each block.
Chanae
of
uratreforfft
o
Change
o{ hctrmorlics.
f
o
T
o
Cutotf
'
him«ii'5
'^
-fc
In addition to adjusting the cut-off frequency
by
means
of
a
knob,
the
tone
is
caused
to
undergo
a
temporal
change (from
the
time
the
sound
is
generated
to
the time
it
ceases) to give
it
an "enve-
lope".
This
is
accomplished by
effecting control on
the
filter's
cut-off frequencies
by means
of
the
envelope
generator.
VCA
The
VCA
block adds an "envelope"
to the
volume.
The
process
starting
from
the generation of
the
sound
up
to the point the sound
gradually fades away
is
governed
by
the
envelope
generator's
ATTACK
TIME,
DECAY
TIME,
SUSTAIN
LEVEL,
RELEASE
TIME
(A.D.S.R.),
changing the amplification degree
of
the
VCA
amplifier.
VCA
and
Ewe\oae
V^f\
Oatput
V
It
•
VCO
The
VCO
block produces sound
sources of
fre-
quencies corresponding
to
the
intervals of the key-
board.
The
sound
source waveforms
produced" by
the
VCO
are sawtooth waves and
square waves
that
include
many
harmonics
in a regular
manner. These
waves
are oscillated, using an electronic
circuit.
•
VCF
The
VCF
block determines
the tone, changing
the
harmonic spectrum of
the
sound
sources
by
cutting,
or
emphasizing,
certain parts of
the
harmonics by
passing
the
sound sources through
filters.
The
boundary between
the portion that passes through
(he
filter
and
the portion that
is
cut off
is
known
as
the cut-off frequency.
The
VCF
creates the charac-
teristic
harmonic
spectrum, by
varying the cut-off
frequency.
The
signals
from
the
VCO
reach the
VCF
where
they
undergo
a
change with
regard to
their
harmonic
spectrum
by
being passed
through
a filter.
The
sig-
nals,
now
containing
certain tone
characteristics, are
given
a
volume
"envelope"
at
the
VCA
and
then
fed
out. In
this
way,
all
elements of
the properties of
sound
are controlled
electronically,
by
utilizing the
three
elements of sound and
the "envelope." The
synthesizer
has,
in
addition
to the
blocks described
above, other blocks such
as
the
LEO
which
permit
further changes
in
the sounds. But
in
this case too,
the
job
is
performed by
controlling the three
ele-
ments
of sound and
the envelope.
We
hope
that the
points described
in this section
may
be helpful to understand
the
immense
possibili-
ties
and
great pleasure awaiting you on
a
path
that
will
lead
you
into
a
new
world of
music using
a
totally
new
musical instrument,
the synthesizer.
©