Orban OPTIMOD-FM 8600Si, Operating Manual

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OPERATION ORBAN MODEL 8600Si
(slow) to 20 dB / second (fast). The increase in density caused by setting the
AGC
R
ELEASE
control to fast settings sounds different from the increase in density caused
by setting the Multiband’s
MB R
ELEASE
control to
F
AST
, and you can trade the two
off to produce different effects.
Unless it is purposely speeded-up (with the
MB R
ELEASE
control), the automatic gain
control (AGC) that occurs in the AGC prior to the multiband compressor makes audio
levels more consistent without significantly altering texture. Then the multiband
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 au-
tomatic 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
RIVE
control) to produce the desired amount of AGC
action and then fine-tune the compression and clipping with the Five-Band struc-
ture’s controls.
AGC Gate Thresh (Threshold) control determines the lowest input level that will
be recognized as program by OPTIMOD-FM; lower levels are considered to be noise
or background sounds and cause the AGC or multiband compressor to gate, effec-
tively freezing gain to prevent noise breathing.
There are two independent gating circuits in the 8600Si. The first affects the AGC
and the second affects the multiband compressor . Each has its own threshold con-
trol.
The multiband compressor gate causes the gain reduction in bands 2 and 3 of the
multiband compressor to move quickly to the average gain reduction occurring in
those bands when the gate first turns on. This prevents obvious midrange coloration
under 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 neigh-
bor) and independently sets the gain of the lowest frequency band according to the
setting of the
DJ B
ASS boost control (in the Equalization screen). Thus, without in-
troducing obvious coloration, the gating smoothly preserves the average overall fre-
quency response “tilt” of the multiband compressor, broadly maintaining the “au-
tomatic equalization” curve it generates for a given piece of program material.