ISP Technologies THETA Head - Manual (Page 6)

5. SWEEP FREQUENCY CONTROL
This control works in conjunction with the MID boost/cut control and adjusts the
center frequency of the MID boost or cut signal. At the full counter clockwise setting
the midrange frequency will be at 300Hz, at the full clockwise setting the center
frequency of the midrange will be at 6KHz. NOTE: when the MID control is set at
12:00 straight up the SWEEP will not have any affect on the signal since there is not
boost or cut being applied.
6. TREBLE CONTROL
The TREBLE control adjusts the boost or cut that is applied in the high frequency
portion of the spectrum of CLEAN CHANNEL. The maximum TREBLE boost and cut
range is +/-15 decibels.
7. REVERB LEVEL CONTROL
The REVERB control adjusts the amount of digital reverb that is added when using the
CLEAN channel. The digital REVERB in the THETA amplifier has a bandwidth of 18KHz
and also includes a digital implementation of the Decimator noise reduction to ensure
that the digital reverb has a dynamic range greater than 110db.
8. DECIMATOR NOISE REDUCTION
The CLEAN channel DECIMATOR control adjusts the threshold of the CLEAN channel
noise reduction. The DECIMATOR noise reduction is a down low-level downward
expander incorporating ISP‟s patent pending TIME VECTOR PROCESSING.
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.