Yamaha CS-10 Owner's Manual page 5

such
as
2-fold, 3-fold,
and so on.
You
will
see that the
wave form
will
gradually
come
to
resemble
a
saw-tooth-
like
wave
form.
In
addition
to this,
you
will
see that
this
saw-tooth
wave form
has a cycle similar to that
of
the
sine
wave
that has
been used
as
the
basis
.
This
sine
wave
that has
the
basic cycle
is
referred to
as
the funda-
mental sound and
the
sine
waves of harmonic
over-
tones as
the harmonics. In the case
of
musical
instru-
ments,
the
way
in
which harmonics
are
contained
in
sounds
will
depend on
the
arrangement
by which
sounds
are
caused
to
generate.
When we
discuss
the difference
in
tones
(wave
forms),
it
is
the
same
as discussing
what
kind of harmonics
the
sounds contain
.
Saw-tooth
wave
Wave form
obtained
by
adding
harmonics of the 2nd
-
10th
to
fundamental wave.
Wave form
obtained
by
adding
the
2nd harmonics
to funda-
mental wave.
Wave form
obtained
by
adding
the
2nd and
3rd
harmonics
to
fundamental
wave.
VCF
renders the harmonic spectrum with
characteri-
stics,
by
varying the cut-off frequency.
Wave form
variation
Filter
(LPF) Wave form
changes.
Harmonic
structure variation
r
Level
Harmonics
t
! ,
Level
h
^
f
'
Level
Disappears
by
'being
cut
off.
Fundamental
Cut off frequency
In addition to adjusting the cut-off frequencies
by
means
of
a
knob, the tone
is
caused
to
undergo
a
change
with time (from the time the sounds generate
to
the
time they
die
away)
to give
it
an
"envelope''. This
is
accomplished by
effecting control
on
the
filter's
cut-off
frequencies
by
means of
the
envelope
generator.
VGA
The
VCA
block functions to
give
volume
an envelope.
The
mode
of volume
starting
from
the generation
(positive
edge) of the sound,
up
to
the point the
sound
fades
away
leaving reverberations
is
produced by
con-
trolling
the envelope generator's
A.D. and
S.R.,
which
in
turn, controls the amplification
degree of the
VCA
amplifier.
STRUCTURE OF SYNTHESIZER
In the synthesizer,
sounds
are synthesized
by
effect-
ing
control
on
the four properties
of sound
(the three
elements of sound
plus
the envelope), dividing control
into
4
blocks.
Control of
intervals
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 gene-
rator).
The
following describes the controls
by
each
block.
VCO
The
VCO
block produces
a
sound
source
of
fre-
quencies corresponding
to
the intervals
of
the
keyboard.
The sound
source
wave forms produced by
the
VCO
consists
of such waves
as
saw-tooth waves and square
waves
that include
many
harmonics
in
a regular
manner.
These waves
are oscillated, using
an
electrical circuit.
VCF
The
VCF
block
makes
the tone,
by
changing the
harmonic spectrum of
the
sound
sources
by
cutting,
or
emphasizing,
a part
of the
harmonics by
passing the
sound sources through
filters.
The boundary between
the portion that passes
through
the
filter
and the portion
that
is
cut off
is
known
as
the cut-off
frequency.
The
VCF
signals
Envelope generator
VCA
output
The
intervals oscillated
by
the
VCO
reach the
VCF
where they undergo a change with
regard to
their
harmonic spectrum by
being passed through
a
filter.
These
signals
rendered with
certain
tone
characteristics
are
given a
volume envelope
at
the
VCA
and
are
fed out.
In this
way,
all
elements of
the properties
of sound
are
controlled
electrically,
by
utilizing
the three elements of
sound and
the envelope.
The
synthesizer has,
in
addition
to the blocks described, other blocks such
as
the
LFO
that
renders
delicate
changes to the sounds. But
in this
case,
too, the job
is
performed
by
controlling the three
elements of
sound and
the envelope.
We
hope
that
you
have
fully
understood
the points
described
in this section in
order to enjoy
the
immense
pleasure
of opening
a
path
that
will
lead
you
into a
new
world of music
using
a
new
musical instrument,
the synthesizer.
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