11
now, so that the synthesizer "produces" a sound only when you
have pressed a key. Experiment with various settings of the ENV
2 controls, and with setting various relationships between the
VCF frequency control and the knob (#5) that determines control
signal amplitude.
NOTE: These relationships are the most crucial ones in the syn-
thesizer; until they are mastered, you will not be getting
the most that you can from your instrument. A quick summary
of the most important points to learn: (verify each one as
you read.)
a) in many keyboard setups the filter is either closed, to
open only under control of ENV 2, or (less often) open,
to be closed only under control of ENV 2.
b) a highpass filter is closed when its frequency is high; a
lowpass filter is closed when its frequency is low; a
bandpass filter is closed when its frequency is either
high or low; and a notch filter is always open.
c) when the control input attenuator is rotated left, the
incoming signal from ENV 2 drives the filter frequency
down; as it is rotated to the right, the ENV 2 signal
drives the filter frequency up.
d) as the filter resonance is increased, its output level
will--generally--increase. Compensate by lowering
slightly the level of the input audio level. At maximum
resonance a very small input signal is enough to produce
full output from the filter (in a very narrow band of
frequencies).
C. INTERRUPTED SOUND
If the filter manual frequency setting is at minimum, and the
mode control is set for lowpass operation, and the control
input attenuator is at maximum right, the filter alone will be
capable of producing "events" under keyboard control. In other
words, with these settings you will hear nothing until a key is
depressed, thus gating the ENV 2 "on" which opens the filter to
allow a signal to pass through.
In many cases, however, you will want to use the filter for
some other purpose--perhaps controlled by the LFO, or even not
controlled at all except manually. Good oboe and bassoon tim-
bres, for example, require a resonant filter at a constant fre-
quency.
In all of these cases, you will need to use the VCA to inter-
rupt the continuous source sound and produce "events."
