ISP raises the bar on ultimate guitar performance with the new, novel patent pending Decimator(TM) ProRackG. The Decimator ProRackG guitar noise reduction system defines a new standard for excellence in real time noise reduction performance. The Decimator ProRackG was designed to provide the maximum possible performance in a rack mount dual channel noise reduction system designed specifically for extremely high gain guitar amplifiers. The Decimator ProRackG is the only system in the world designed with two channels of single ended noise reduction configured specifically for high gain guitar applications allowing one channel to deliver noise reduction for the guitar directly and a second channel to eliminate amplifier gain noise. Channel one eliminates the 50 or 60 cycle hum, buzz, stage light noise and any other noise picked up directly by the instrument. The ProRack channel one output drives the front end of your guitar amplifier and eliminates all of the input noise picked up by the guitar. The control circuit of the second channel detects and tracks the guitar signal directly while the signal processing audio chain is patched into the effects loop of the high gain guitar amplifier. Now you can quiet down even the most insane amounts of noise with any amplifier system incorporating a series effects loop. The Decimator ProRackG will also solve the typical high gain feedback or squealing problem that the high gain guitar player fights. You know how difficult this problem can be. You play staccato notes and in between each note you have a squeal or burst of feedback that's virtually impossible to control. Problem solved with the Decimator ProRackG. By proper setting of the threshold for channel one and channel two you can eliminate this problem for good. The Decimator ProRackG has dual processing channels incorporating both low-level downward expansion and dynamically controlled low-pass filtering in a very easy to use single rack space unit. The Decimator ProRackG is based on ISP Technologies patent pending “Time Vector Processing” which provides the most adaptively dynamic release response characteristics of any real time noise reduction system. The patent pending Time Vector Processing dynamic response circuit is used to control the release time constant of both the downward expander and dynamic filter. Not only does the Decimator ProRackG deliver the most stunning noise reduction, it also solves the problem of needing to adjust the Threshold setting every time you change gain or switch channels. By using the input guitar signal to drive both channels' level detection circuitry, the ProRackG needs no other adjustments once the thresholds are set based on the guitar input. This will give you the correct threshold with clean, crunch and even monstrous amounts of gain and if you use pedals you can insert them in the loop between the output of the Decimator Channel 1 and the input of the guitar amplifier. The block diagram below shows the typical system connections for use

with a high gain amplifier.

Players keep asking how the ProRackG works without any required change in the threshold when changing from clean to distort, read on: As you can see from the above diagram, the ProRackG has two channels of noise reduction. The guitar plugs directly into the channel 1 input and the level and frequency detectors for both channel 1 and channel 2 measure the direct guitar input signal. This means that changing from a clean sound to a high gain distorted will not affect the signal seen by the detectors. This means that you can use the first Decimator channel to eliminate any noise that the guitar picks up directly like transformer hum, light noise etc. You simply adjust the threshold of channel 1 to eliminate this front end noise. The second channel is inserted into the effects loop of your amplifier (requires a series effects loop) and this channel will clean up the high gain preamp noise, ground loop hum, and any other noise that you have in this chain. The beauty of its operation is that the second channel is working to clean up this high gain noise but in response to the actual guitar signal, which typically has a much higher dynamic range than what you would see if this channel's detector's were detecting the high gain signal. By setting the threshold of channel 2 to eliminate all of the gain noise when the guitar signal decays into the noise this will also provide the correct setting for your clean channel.

Time Vector Processing is the core technology that makes the Decimator work with such amazing transparency.   The Time Vector Processing compares the long term envelope of the input signal with the short term envelope of the input signal and generates a "Time Vector" or "Time Correction" signal.   This time correction signal dynamically changes the release response of the expander and dynamic filter.  If the input signal is a slow decaying long sustained note the Time Vector Processing circuit senses that the envelope of the input signal is a slowly decaying signal and sets the release time for a slow smooth release.    If however, the input signal is a short staccato note with a fast decay the Time Vector circuit will produce a Time Correction signal which will instantaneously change the release time of the downward expander and dynamic filter to an extremely fast response.   The Time Vector Processing circuit continuously monitors the input signal and alters the release time allowing the Decimator to adapt its response to provide an optimized response for any guitar signal.   The Time Vector Processing circuit provides a variable response time ratio of greater than 1000 to 1.   No other real-time noise reduction system can offers this degree of adaptability and tracking.