Roland SH-1 Instruction Manual page 5

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CONTROLLE
D
VCO
PITCH =
FREQUENCY
VCF
TONE COLOR
=
HARMONIC CONTENT
VCA
LOUDNESS
*
AMPLITUDE
CONTROLLER
\
KEYBOARD The most
common
use
of the key-
board
control
voltage
is
for the
control of the pitch of a
VCO;
the
pitch
produced
will
correspond
to
the
key
pressed.
The tone
color of
most instruments
will
vary with
pitch; higher pitches
often produce brighter tone colors,
lower
pitches
darker tone colors.
For
this
purpose, the
VCF
can be
controlled
by
the
keyboard.
The
control of loudness by
means
of
the
keyboard
is
of
little
practical use;
the SH-1 has no provision for
this
type of control.
ENVELOPE
With some sounds,
it is
desirable to
incorporate pitch
changes during the
production
of
each
note.
The SH-1
contains a special
envelope
generator (autobend) provided exclu-
sively for this
purpose.
The
tone color of
many
instruments,
particularly
the
wind
instruments,
changes during the production of
each note. This
effect
can be produced
with envelope generator control of
the
VCF.
Raising the
VCF
RESO-
NANCE
control
will
produce sounds
possible
only on the synthesizer.
The loudness pattern
(or
articulation)
of
a
sound
is
produced by using the
output of
the envelope generator to
control the
VCA.
LFO
(MODULATOR)
The
LFO
(Low Frequency
Oscilla-
tor)
produces low frequency
wave
forms. Using the
LFO
sine
wave
out-
put to
control the pitch of the
VCO
will
produce
vibrato effects.
The
LFO
square
wave output
will
produce
trills.
With
some
sounds, the tone color
will
vary
at
the
same
rate as
vibrato.
This can be done with
LFO
control
of the
VCF.
Raising the
VCF
RESO-
NANCE
control
will
produce "growl"
effects.
The
SH-1 does not
provide for
LFO
control of the
VCA; however,
the
square
wave
output of the
LFO
can
be used for
triggering
the envelope
generators
to
produce rapidly repeat-
ing notes.
BASIC
SYNTHESIZER
THEORY
In
the synthesizer, then, the three qualities
of
sound
are
controlled
by
the
VCO
(pitch),
VCF
(tone color),
and
VCA
(loudness).
The
tremendous
versatility of
the synthesizer
is
due
to the principle of voltage control.
The
above
table
shows some
of the
possibilities.
The
keyboard has
two
outputs:
a
control voltage
and
a
gate pulse.
The
level
of
the control
voltage
will
correspond
to the
last
key
pressed.
The
control voltage
output
is
most often used
to
control the
frequency
of the
VCO,
thus,
when
8
key
is
pressed, the
VCO
will
produce the
pitch
which
is
related to that key.
The
key-
board produces
a
gate pulse each time
a
key
is
pressed.
The
gate pulse
is
most
often
used to
trigger the envelope
generator
into operation.
The
control voltage
output of the envelope
generator, then, "opens" the
VCA
to
let
the
sound wave
out,
thus
the
synthesizer
produces
sound
each time
a
key
is
depressed.
The shape
of
the envelope
is
controlled
by the
envelope generator
sliders.
When
the sliders are
set, the
envelope generator
will
generate
a
con-
trol voltage
which
corresponds
to the
shape
of
the desired envelope.
When
this
control voltage
controls the
VCA,
it
regulates the loudness
level
of
the
sound
so that the
loudness
will rise
and
fall
in
the desired pattern.
Fig.
4 shows the
output
sound wave
when
the
envelope generator
controls
are set
to
produce
a
violin-like
envelope,
and
Fig.
5
shows
the
output
sound
for
a
piano-
or guitar-like
envelope.
The
tone color of
many
types
of
sound
will
often
change during the production of
each
note. This can be
done
with the
synthesizer by
using the
output
of
the envelope generator to
control the
VCF.
There
are
two
other sources of control voltage:
the
LFO
(Low
Frequency Oscillator)
and the
S/H (Sample and Hold), each
of
which can be
used
to
control various synthesizer functions.
In
the following pages, the functions of each of
the synthesizer elements
is
explained
in detail.
When
trying various sounds, try
to analyze
exactly
what
is
happening;
this will give
you
a
better
understanding
of
thesynthesizer.
Synthe-
sizer
sounds are very
much
enhanced by
the use
of effects units
such
as
echo chambers,
re-
verberators, chorus effects,
phase
shifters,
flangers, etc, thus their use
is
highly
recom-
mended.
FIG.
-VIOLIN-LIKE
SOUND
FIG. 5
-PIANO-LIKE SOUND
FIG.
6
- PARTS OF ENVELOPE
-A*|*»D-