Orban OPTIMOD 6300 Operating Manual page 152

3-10
OPERATION
enhancing bright material. It interacts synergistically with the 5-band compressor to
produce sound that is bright and present without being excessively shrill.
Multiband Compression: The multiband compressor can be operated in 5-band or
2-band mode. In 5-band mode, each band compressor has a K
A soft knee and gentle ratio are particularly useful in production and mastering ap-
plications, allowing subtle compression that retains as much of the dynamics of the
input program material as the operator desires.
Several band-coupling controls allow the gain reduction of a given band's compres-
sor to be partially controlled by the gain reduction in its neighboring band's com-
pressor. These coupling controls allow anything from quasi-wideband compression
to fully independent multiband compression.
A clipper, embedded in the crossover, protects bands 1 and 2 from transient over-
shoot. This clipper has a shape control, allowing you to vary the "knee" of its in-
put/output transfer curve from hard (0) to soft (10).
Low-IM Look-Ahead Limiter: The 6300's peak limiter prevents overshoots by ex-
amining a few milliseconds of the unprocessed sound before it is limited. This way,
the limiter can anticipate peaks that are coming up.
It is important to minimize audible peak-limiter-induced distortion when
one is driving a low bitrate codec because one does not want to waste
precious bits encoding the distortion. Look-ahead limiting can achieve
this goal; hard clipping cannot.
One can model any peak limiter as a multiplier that multiplies its input
signal by a gain control signal. This is a form of amplitude modulation.
Amplitude modulation produces sidebands around the "carrier" signal.
In a peak limiter, each Fourier component of the input signal is a sepa-
rate "carrier" and the peak limiting process produces modulation side-
bands around each Fourier component.
Considered this way, a hard clipper has a wideband gain control signal
and thus introduces sidebands that are far removed in frequency from
their associated Fourier "carriers." Hence, the "carriers" have little ability
to mask the resulting sidebands psychoacoustically. Conversely, a look-
ahead limiter's gain control signal has a much lower bandwidth and pro-
duces modulation sidebands that are less likely to be audible.
Simple wideband look-ahead limiting can still produce audible inter-
modulation distortion between heavy bass and midrange material. The
look-ahead limiter in your Optimod uses sophisticated techniques to re-
duce such IM distortion without compromising loudness capability.
Dialnorm and Limiting: The 6300 supports the dialnorm metadata value in Dolby
Digital® transmissions to the consumer. When used to process a Dolby Digital
transmission, the 6300 can be easily set up to ensure that the loudness of your
transmission is identical to that of other properly set up Dolby Digital transmis-
sions.
If you are not driving a Dolby Digital channel, we recommend turning
the 6300's D
located in S
R O
IALNORM EFERENCE UTPUT
.
>D
ETUP IALNORM
ORBAN MODEL 6300
and R
NEE
.
(R O ) to O
This control is
EF UT FF
ATIO control.