Orban OPTIMOD-FM 5500 Operation Manual page 152

3-28
OPERATION
processing (such as a CLASSICAL preset). The AGC is also ordinarily defeated if you
are using a studio level controller (like Orban's 8200ST). However, in this case it is
better to defeat the AGC globally in System Setup.
AGC DRIVE control adjusts signal level going into the slow dual-band AGC, and
therefore determines the amount of gain reduction in the AGC. This also adjusts the
"idle gain" — the amount of gain reduction in the AGC section when the structure
is gated. (It gates whenever the input level to the structure is below the threshold of
gating.)
The total amount of gain reduction in the Five-Band structure is the sum of the gain
reduction in the AGC and the gain reduction in the multiband compressor. The total
system gain reduction determines how much the loudness of quiet passages will be
increased (and, therefore, how consistent overall loudness will be). It is determined
by the setting of the AGC D
or PPM is peaked, and by the setting of the M
AGC REL ("AGC Master Release") control provides an adjustable range from 0.5
dB/second (slow) to 20 dB/second (fast). The increase in density caused by setting the
control to fast settings sounds different from the increase in density
AGC R
ELEASE
caused by setting the Multiband's M
trade the two off to produce different effects.
Unless it is purposely speeded-up (with the AGC R
gain control (AGC) that occurs in the AGC prior to the multiband compressor makes
audio levels more consistent without significantly altering texture. Then the multi-
band compression and associated multiband clipper audibly change the density of
the sound and dynamically re-equalize it as necessary (booming bass is tightened;
weak, thin bass is brought up; highs are always present and consistent in level).
The various combinations of AGC and compression offer great flexibility:

Light AGC + light compression yields a wide sense of dynamics, with a small
amount of automatic re-equalization.

Moderate AGC + light compression produces an open, natural quality with
automatic re-equalization and increased consistency of frequency balance.

Moderate AGC + moderate compression gives a more dense sound, particularly
as the release time of the multiband compressor is sped up.

Moderate AGC + heavy compression (particularly with a FAST multiband release
time) results in a "wall of sound" effect, which may cause listener fatigue.

Adjust the AGC (with the AGC D
AGC action, and then fine-tune the compression and clipping with the Five-Band
structure's controls.
AGC GATE ("AGC Gate Threshold") control determines the lowest input level that
will be recognized as program by OPTIMOD-FM; lower levels are considered to be
control, by the level at which the console VU meter
RIVE
ULTIBAND
R
ULTIBAND ELEASE
control) to produce the desired amount of
RIVE
ORBAN MODEL 5500
D (compressor) control.
RIVE
control to F , and you can
AST
control), the automatic
ELEASE