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OPTIMOD-PC
There are two independent gating circuits in OPTIMOD-PC. The first affects the AGC
and the second affects the five-band compressor. Each has its own threshold control.
The multiband silence gate causes the gain reduction in bands 2 and 3 of the five-
band compressor to move quickly to the average gain reduction occurring in those
bands when the gate first turns on. This prevents obvious midrange coloration un-
der gated conditions, because bands 2 and 3 have the same gain.
The gate also independently freezes the gain of the two highest frequency bands
(forcing the gain of the highest frequency band to be identical to its lower
neighbor), and independently sets the gain of the lowest frequency band according
to the setting of the DJ B
out introducing obvious coloration, the gating smoothly preserves the average
overall frequency response "tilt" of the five-band compressor, broadly maintaining
the "automatic equalization" curve it generates for a given piece of program mate-
rial.
If the
MB GATE
tion screen) is disabled.
DWNEXP ("Multiband Downward Expander Threshold") determines the level below
which the single-ended noise reduction system's downward expander begins to de-
crease system gain and below which the high frequencies begin to become low-pass
filtered to reduce perceived noise. There are two controls: the MB D
control sets the expansion threshold in Bands 1-4, while the B5 D
trol sets the expansion threshold in Band 5. Activate the single-ended dynamic noise
reduction by setting these controls to a setting other than O
The single-ended noise reduction system combines a broadband downward ex-
pander with a program-dependent low-pass filter. These functions are achieved by
causing extra gain reduction in the multiband compressor. You can see the effect of
this extra gain reduction on the gain reduction meters.
Ordinarily, the gating on the AGC and multiband limiter will prevent objectionable
build-up of noise and you will want to use the single-ended noise reduction only on
unusually noisy program material. Modern commercial recordings will almost never
need it. We expect that its main use will be in talk-oriented programming, including
sports.
Please note that it is impossible to design such a system to handle all program mate-
rial without audible side effects. You will get best results if you set the MB D
E
control of the noise reduction system to complement the program mate-
XPANDER
rial you are processing. The MB D
is noisy and lower when the input is relatively quiet. The best way to adjust the MB
control is to start with the control set very high. Reduce the control
D
E
OWN
XPANDER
setting while watching the gain reduction meters. Eventually, you will see the gain
increase in sync with the program. Go further until you begin to hear noise modula-
tion—a puffing or breathing sound (the input noise) in sync with the input program
material. Set the MB D
noise modulation. This is the best setting.
boost control (in the Equalization screen). Thus, with-
ASS
control is turned
, the
O
FF
E
OWN
XPANDER
control higher until you can no longer hear the
E
OWN
XPANDER
control (in the Equaliza-
DJ B
ASS
OWN
.
FF
should be set higher when the input
OPERATION
E
OWN
XPANDER
con-
E
XPANDER
OWN
3-49
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