ISP Technologies THETA PRE AMP PEDAL - Manual (Page 7)

DECIMATOR CONTROL NOISE REDUCTION CONTROL
The DECIMATOR control adjusts the THRESHOLD of the Decimator G-String II. The
Decimator works with both the Clean PREAMP and the DISTORT circuit and will switch
completely out of the signal path when both the PREAMP and DISTORT circuits are
switched off. If either the PREAMP or DISTORT circuits are switched on the
Decimator circuit will be automatically switched into the signal path. The DECIMATOR
noise reduction is a down low level downward expander incorporating ISP’s patented
TIME VECTOR PROCESSING. The Decimator is covered under multiple patents
including 6,944,305, 7,532,730 and 7,957,546 with other patents pending.
A BRIEF EXPLANATION OF THE DECIMATOR NOISE REDUCTION SYSTEM
Low Level Downward Expansion is performed by use of a high quality voltage
controlled amplifier controlled by an RMS based audio level detection circuit. A Time
Vector Processing circuit is used which varies the release response over a 1000 to 1
ratio and controls the release response of the Downward Expander. The release
response will be extremely fast, on the order of 2 milliseconds, if the input signal has
a fast decaying envelope and upwards of 2 seconds if the input signal has a slow
decaying signal. Downward Expansion takes place when the input signal level drops
below the preset threshold. For example: if the threshold is set for 0db and input
signal of 0db with produce no expansion. As the input signal drops below 0db
downward expansion starts and increases exponentially the farther the input signal
drops below the threshold point. The figure below shows the response of the
Expander with a 0db threshold.