Rocktron Hush II Guitar Noise Reduction (Used)
Hush noise reduction is the standard with touring rigs worldwide. Now you can tap into the same great circuitry to wipe out hiss, pickup buzz, and unwanted feedback. The Rocktron HUSH pedal delivers 65dB of signal cleanup, while your signal integrity remains unaffected.
HUSH signal cleanup is provided with up to 65dB of effective noise reduction for eliminating hiss, unwanted feedback and noise from pickups and stage lighting.
Guitar Player Magazine wrote that a “HUSH” pedal will work for all guitar-related noise problems: it’s perfect” and “its potent noise-killing abilities will be fully appreciated.”
Rocktron’s patented HUSH® noise reduction is a single-ended system that combines the principles of dynamic filtering and low-level downward expansion.
Dynamic Filtering
Dynamic filtering is achieved by dynamically-controlling a low pass filter to open and close the bandwidth of the output signal depending upon the amount of mid and high band information present in the input signal. The filter bandwidth will only open far enough to pass the highest frequency information in the input signal, thus reducing the noise above it.
For example, if the highest frequency present in the input signal is 8kHz, the filter will open to pass up to 8kHz while the noise from 8kHz to 20kHz would be reduced. If a signal with frequency components up to 20kHz appears at the input, the dynamic filter will open to its full extreme (40kHz).
Downward Expansion
The second half of the HUSH® process incorporates downward expansion. The low level expander of the HUSH® system operates like an electronic volume control. The HUSH® system 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 preset threshold point, the VCA circuit remains at unity gain. (This means that the output signal level is equal to the input signal level.) As the input signal level drops below the user preset threshold point, downward expansion begins. It is at this point that the expander acts like an electronic volume control and gradually begins to decrease the output signal level relative to the input signal level.
Downward Expansion
The second half of the HUSH® process incorporates downward expansion. The low level expander of the HUSH® system operates like an electronic volume control. The HUSH® system 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 preset threshold point, the VCA circuit remains at unity gain. (This means that the output signal level is equal to the input signal level.) As the input signal level drops below the user preset threshold point, downward expansion begins. It is at this point that 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.