Roland SH-1 - VCF Frequency and VCA Adjustments

2.
RESONANCE CONTROL
This
control accents the frequencies
at
the
cutoff point of the VCF. At
"0",
the
RESONANCE control has
no
effect. The
effect will become stronger, the higher
the
control is raised.
With the
RESONANCE control
at a
high
position, moving the CUTOFF FREQ slider
will produce sounds peculiar
to
the synthe-
sizer.
At about
"8",
the
frequencies
at the cutoff
point
are accented so
strongly
that the
VCF
starts
to oscillate
by
itself, or in
other words, it begins generating a sine
wave even with no input
to the
VCF.
The
frequency
of this sine wave will
depend
on the
position of the VCF
CUTOFF FREQ control.
When
the
KYBD slider is
raised, the
pitch
can
be
controlled
with the keyboard to
play music. In addition, a variety of
effect
sounds are also obtained
by
the oscillating
VCF.
When the resonance control
is set at a
high
position,
total
volume may fall. The volume
should be compensated for with the
volume control.
3.
ENV-1
CONTROL
With this control raised, the
cutoff
point of
the
VCF will change during the production
of each note,
following
the pattern dictated
by
the setting
of ENVELOPE GENERA-
TOR 1. This type
of VCF
modulation
is
very
often used with brass sounds.
For example, with the ENV-1 controls at
around A=0, D=5, S=0, R=5, thek_ type
envelope controls the VCF. The
VCO
waveform,
a
square
wave in this case, is
modified from A
to
E as shown at the right
each time a key is depressed.
At the instant a key is
depressed,
the
cutoff
frequency is
high and the original
VCO wave
passes unchanged.
As time passes, the envelope voltage falls
and the cutoff frequency lowers, changing
the waveform from
B to D.
If
the
cutoff frequency
slider is
lowered
below
a
certain level, signals
are
blocked as
shown
at
E.
With
the
ENV-1 polarity in the inverted
position
(V^hthe
VCO
waveform changes
in
the
opposite way. Normally, the Polarity
switch is set in the
normal
positionf/^-J.
The
inverted
(
\y^ ) envelope is used for
producing special effects.
»
FUNCTION
OF
RESONANCE
CONTROL
t
FREQUENCY
CONTROL
OF VCF
BY
ENVELOPE
(K_)
VCF
^
B
VCF
VCF
No
signal
passes.
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