ISP Technologies THETA 212 Combo - Manual (Page 7)

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 COMBO 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.