Rocktron Utopia B200 - Manual (Page 25)

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The HUSH ® function is accessible in all presets - regardless of the configuration currently recalled.
HUSH is a patented single-ended noise reduction system. The HUSH system contained in the
UTOPIA B200, though modeled after the latest analog HUSH design, is a fully digital implementation
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 utilizes a voltage-controlled amplifier (VCA) circuit which can control the gain
between the input and the output from unity to 30, 40 or even 50(dB) of gain reduction. When the input
signal is above the user preset 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 begins. At this point the expander acts
like an electronic volume control and gradually begins to decrease the output signal level relative to the
input signal level. As the input signal drops further below the threshold point, downward expansion in-
creases. A drop in the input level by 20(dB) would cause the output level to drop approximately 40(dB)
(i.e., 20(dB) of gain reduction). In the absence of any input signal, the expander will reduce the gain so
that the noise floor becomes inaudible.
The HUSH circuit is located after the A/D converter in the signal chain to reduce any noise gener-
ated from the Bass and the A/D converter. This ensures a quiet input signal to the preamp section. Be-
cause the preamp section of the UTOPIA B200 is digital, it is virtually noise-free (even for the high-gain
6. HUSH ® Function
The HUSH I/O parameter simply determines whether the HUSH® circuit is ac-
tive for the current preset.
The EXP THRESHOLD (Expaner Threshold) parameter determines the level at
which downward expansion begins. For example, if the EXP THRESHOLD was
set at -20(dB) and the input signal dropped below -20(dB), downward expansion
would begin.
HUSH I/O
EXP
THRESHOLD
channels). Therefore, a quiet input signal to the preamp will result in a quiet output signal.
The PARAMETER SELECT knob will allow you to access these Hush parameters: