Yamaha CS-15 Owner's Manual page 9

FUNCTIONS
VCO
The
VCO
1
and
VCO
2
blocks
consist of
oscillators
producing the sawtooth waves
correspond-
ing to the pitch of the keys
(CONTROL
VOLT)
from
the keyboard
and of
the
Wave Shape
Converter
(WSCJ
to convert
sawtooth waves
into
square or
triangle waves.
(D®
FEET
The
keyboard
covers three octaves with 37
keys.
By
making
use of
the
FEET
switches, the
sound
range
to
be covered can be
shifted
as
shown
in
the
diagram
below.
FEET
2FEET
4FEET
'
8 FEET
*~
16FEET
'
32
FEET
'
64FEET
'
~*
-i
® ©
WAVE
These
switches
select
the
waveforms of
the sound
sources.
A
:
TRIANGLE WAVE
Though
this
waveform
also has
harmonics of
the next
odd number
like
the square wave,
soft
sound
almost
equivalent to
sine
wave
(pure
sound)
can be obtained
since
it is
rich in
fundamentals.
K:
SAWTOOTH
WAVE
This
waveform
has
harmonics
of multiple
in-
tegrals.
Unlike
triangle
and
square waves,
it
has
richer harmonics, often being used
as
pseudo
sound
source for imitating instruments.
n_:
SQUARE
WAVE
This
waveform
has harmonics
of the
next odd
number, being very
like
the spectrum of
a
musical instrument such
as a
clarinet,
but
it is
possible to
change
the
harmonic
structure
by
the
PW
and
PWM
knobs and
thus
this
wave-
form
is
suitable as a
sound
source to
produce
sounds
peculiar to the synthesizer.
® ®
LFOMOD
This block modulates
the
VCO's
oscillating
fre-
quency by means
of
a
LFO.
If
this
knob
is
turned
towards
10, the
modulation
will
become
deeper.
© ®
PW
This
knob
changes
the pulse width of the square
wave
(50%
to 90%). Changing
the pulse
width
® © ®
changes
the
harmonic
structure
of
the square
wave
and
allows
it
to be used
as a
sound
source
different
from one produced by
a
symmetrical
square wave.
PW
= ^X10
—
w
Harmonic components
when
PW
is
changed.
rrvftnr
Frequency
(F)
<Q>
®
PWM
This
knob
changes
the pulse
width of
the square
wave
at
cycles equivalent to the setting
of
the
LFO's
SPEED
knob.
PWM:
Pulse
width modulation
jururu
© ©
<3
It
changes
in
the order of
LFO:
Sine
wave
©