Rocktron Taboo ARTIST, User Manual, Page: 28 / 79

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HUSH
®
Function
The
HUSH
®
function is accessible in all presets - regardless of the current configuration.
HUSH
is Rocktron's patented single-ended noise reduction system. The
HUSH
system contained in the Artist is a fully
digital implementation, modeled after the latest analog
HUSH
design, achieved through Digital Signal Processing (DSP).
How HUSH works
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, down-
ward expansion will begin. It is at this point that the expander acts like an
electronic volume control, gradually decreasing the output signal level rela-
tive to the input signal level. As the input signal drops further below the
threshold point, downward expansion increases (see figure at right). A
drop in the input level by 20dB would cause the output level to drop ap-
proximately 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 be-
comes inaudible.
The
HUSH
circuit is located after the A/D converter in the signal chain
to reduce any noise generated from the guitar and the A/D converter. This
ensures a quiet input signal to the preamp section. Because the preamp
section of the Artist is digital, it is virtually noise-free (even in the high-gain
mode). Therefore, a quiet input signal to the preamp will result in a quiet
output signal.
HUSH parameters
P
ARAMETERS
HUSH I/O
HUSH THRESH
D
ESCRIPTION
The HUSH I/O parameter simply determines whether the HUSH
®
circuit is active for the current preset.
The HUSH THRESHOLD parameter determines the level at which downward expansion begins. For
example, if the HUSH THRESHOLD was set at -20dB and the input signal dropped below -20dB,
downward expansion would begin.
Hush