Orban OPTIMOD-FM 5700i, Руководство по эксплуатации

Страница: 220 / 335

3-56
OPERATION ORBAN MODEL 5700i
can go without causing unacceptable listener fatigue. However, this sound may
be useful for stations that are ordinarily heard very softly in the background be-
cause it improves intelligibility under these quiet listening conditions. Stations
that are usually played louder will probably prefer one of the slower release
times, where the multiband compressor takes more gain reduction and where
the AGC is operated slowly for gentle gain riding only. These slower sounds are
less consistent than those produced by the
F
AST
setting. Using S
LOW
preserves
more of the source’s frequency balance, making the sound less dense and fatigu-
ing when the radio is played loudly.
The S
PEECH
MB R
ELEASE
control overrides the MB R
ELEASE
control when the
5700i automatically detects speech (page 3-63). You may wish to set the
S
PEECH
MB R
ELEASE
control faster for speech (to maximize smoothness and uniformity)
and slower on music (to prevent excessive build-up of density).
MB 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, effectively
freezing gain to prevent noise breathing.
There are two independent gating circuits in the 5700i. The first affects the AGC and
the second affects the multiband compressor
. Each has its own threshold control.
V2.0 software sets the multiband compressor’s gating threshold with respect to the
signal driving the multiband compressor/limiter, which follows the AGC. Meanwhile,
the AGC gating threshold remains set with respect to the AGC’s input, as it was in
V1.x software. Driving the MB gate detector after the AGC allows the AGC to do its
work of slowly correcting the drive level to later processing, including the multiband
gate.
When the AGC produces 10 dB of gain reduction, the calibration of the MB GATE
control in V2.x software is the same as it was in V1.x software. When upgrading
from V1.x to V2.x, it should thus be unnecessary to change the MB GATE setting in
User Presets unless the AGC’s nominal gain reduction is significantly different from
10 dB.
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.
Note: If the MB G
ATE
T
HRESH
(Gate Threshold) control is turned O
FF
, the
DJ B
ASS
control (in the Equalization screen) is disabled.