4ms Shaped Dual EnvVCA, Руководство пользователя

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For this example we want to invert the envelope, so turn Level all the way counter-clockwise, and turn
Offset to around 2:00. ENV B will now be outputting an inverted envelope that rests at about 5V and
then ducks down when the kick drum plays. Patch this inverted envelope into Channel A’s VCA CV
jack. Run the audio that you want to be ducked (e.g. a drone sound) into Channel A’s Audio In , and
listen to the output on Audio Out . You should hear the drone play at normal volume, and then briefly
get more quiet whenever the kick drum fires. Try listening to the drone and the kick drum
simultaneously to get the full effect.
Adjust Channel B’s Rise and Fall sliders to control how quickly the envelope responds. If the sliders
are set too fast, the envelope will trace the individual peaks of the sound wave, not the overall
envelope, and the result will be like a subtle AM effect. If the sliders are set too slow, the volume won’t
change much when the kick drum fires.
You can also adjust Channel B’s Offset and Level knobs to control the dynamic range of the ducking. If
you want less ducking, turn Level towards center to reduce the amplitude of the envelope. On the other
hand, if the kick drum is quiet you may need to turn Level towards the extreme counter-clockwise
position to generate an envelope with enough amplitude to get the amount of ducking you want. Offset
almost always needs to be between 1:00 and 3:00. If it’s too low, the output will be too quiet, and if it’s
too high, the output will be at maximum volume with very little ducking.
Using Non-Linear Shapes With Follow
When you feed a signal into the Follow jack, the ENV output jack produces different waveforms
depending on the Shape settings. Figure 8 illustrates variation between the outputs with the Shape
slider in different positions. The blue trace is an audio recording of three drum hits, which is fed into the
Follow jack. The magenta trace shows the output when Shape is set to linear: the peaks of this output
are roughly proportional to the peak levels of the input signal.
Since exponential curves change a small amount to small signals, and a large amount to large signals,
when Shape is exponential, low voltages (near 0V) will be diminished, and higher voltages (near 5V)
will be amplified. This can be seen by the orange curve in Figure 8: only the loudest peaks of the blue
trace cause any noticeable output.
On the other hand, logarithmic curves change a
large amount to small signals, and a small amount
to large signals. Setting Shape to this curve
produces the green trace: tiny signals cause
relatively large peaks in the output, while large
differences in the input peaks cause little differences
in the output peaks.
These differences between Shape settings when
using the Follow jack can be used to select the
types of signals you want a channel to respond to.
For example, if you want to only output an envelope
when a loud kick drum occurs, then using an
exponential shape would be the best choice. On the
other hand, if you wanted a signal that responds to
loud and quite signals with relative equality, a
logarithmic shape would be the better option.
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Figure 8: Blue is audio fed into Follow jack. Magenta is
ENV output with linear shape; orange is expo shape;
green is log shape.