Rocktron Velocity VT60 - Manual (Page 8)

5
HUSH
About HUSH ®
HUSH ® is Rocktron's patented single-ended noise reduction system.
The low-level expander of the HUSH system operates like an electronic volume
control. The analog version of 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
50dB of gain reduction.
When the input signal is above the user-defined threshold level, the VCA circuit
remains at unity gain (i.e., the amplitude of the output signal is equal to that of the input
signal). As the input signal level drops below the user-defined threshold level, down-
ward 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
increases. 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.
The figure below shows the typical expansion ratio for various input levels.
V.I.R. Circuitry
The HUSH included in the VT60 also incorporates patented V.I.R. (Variable Inte-
grated Release) circuitry, which intelligently tracks the guitar signal. Long, sustained
notes are allowed to decay naturally without being cut off, while quick, muted notes
release quickly without a trail of noise following.
The HUSH threshold is adjustable via the front panel HUSH control. When set at its
lowest threshold setting (-70), the HUSH circuit is not active.
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