Telex Integrated Signal Processor ISP-100 - Manual (Page 109)

8-39
Processing Components - Gain
Gain
Figure 8-17 Gain component.
Gain (see Figure 8-17) is the first function applied to all ISP-100 input
data. The gain component performs many operations, including metering
of raw input data (pre-fader), application of up to 18 dB gain, 96 dB
attenuation, or full-muting, metering of data after the level has been
changed (post-fader), and polarity inversion.
Metering
Gain includes peak-reading meters. The meters show the amplitude
of the individual digital samples having the largest absolute value.
The meters are graduated in dB and referenced to digital clipping
(dBFS; dB relative to Full Scale).
Because of their peak-reading nature, gain meters are not useful for
monitoring average signal levels as the peak level of a signal can
exceed its average by a tremendous amount. The advantage of true
peak-indicating meters in a digital signal processor like the ISP-100
lies in their ability to indicate digital clipping. Regardless of the
average level of a signal, if any peaks in the signal are clipped then
the Gain meter reads 0 dB.
Gain and Polarity
Application of attenuation within the gain component is accomplished
by multiplying each data sample by a number whose absolute value
lies between 8.0 (+18 dB) and 0.000015625 (-96 dB). Muting is
accomplished by multiplying each sample by zero. Polarity inversion
is accomplished by multiplying by a negative number. All gain and
polarity changes are soft, meaning that they are gradually changed
from the old setting to the new in order to help prevent the
occurrence of clicks or pops.
Bypass
Bypassing the gain component is equivalent to setting its attenuation