Rocktron Cyborg Delay - Manual (Page 11)

HUSH ® is Rocktron's patented single-ended noise reduction system, and is available
in all presets. The HUSH system provided in the Cyborg is a fully digital implemen-
tation, modeled after the latest analog HUSH design, achieved through Digital
Signal Processing (DSP).
The low level expander of the HUSH system operates like an electronic volume
control. The analog version of the HUSH system utilizes a voltage-controlled amplifier
(VCA) circuit which can control the gain between the input and the output from unity
gain to 30, 40 or even 50dB of gain reduction. When the input signal is above the user-
set threshold point, the VCA circuit remains at unity gain. (This means that the
amplitude of the output signal will be equal to that of the input signal.) As the input
signal level drops below the user preset threshold point, downward expansion will
begin. It is at this point that the expander acts like an electronic volume control,
gradually decreasing the output signal level relative to the input signal level. As the
input signal drops further below the threshold point, downward expansion increases
(see figure below).
A drop in the input level by 20dB would cause the output level to drop approximately
40dB (i.e., 20dB of gain reduction). In the absence of any input signal, the expander
will reduce the gain so that the noise floor becomes inaudible.