Optimod-AM 9400 V1.2 Operating Manual - Orban

OPTIMOD-AM DIGITAL OPERATION 3-59
tabs in the 9400 PC Remote application.
The AGC and Stereo Enhancer controls are common to both the analog AM and
digital radio processing chains and are discussed in their own sections above.
Multiband Drive (See page 3-46.)
Multiband Release (See page 3-47.)
Multiband Gate Thresh (Threshold) (See page 3-49.)
Multiband Downward Expander Threshold (See page 3-50.)
Band Coupling Controls (See page 3-51.)
Multiband Band Mix (See page 3-51.) Note that the digital radio band mix controls
are independent of the analog AM band mix controls and can be used to create an
entirely different sound coloration.
Bx On / Off (see page 3-52).
Bx THR (“Band x Compression Threshold”) controls set the compression threshold in
each band, in units of dB below the final clipper threshold. We recommend making
small changes around the factory settings to avoid changing the range over which
the HD LOOK-AHEAD LIMITER DRIVE control operates. These controls will affect the
spectral balance of the processing above threshold, but are also risky because they
can affect the amount of distortion produced by the look-ahead limiter.
B1-B5 Attack (Time) (See page 3-52).
B1/B2 Xover (Band 1 to Band 2 Crossover Frequency; see page 3-53).
Band 1-5 MaxDeltGR controls set the maximum permitted gain difference between
the left and right channels for each band in the multiband limiter. The 9400
digital radio processing chain uses a full dual-mono architecture, so the channels can
be operated anywhere from fully coupled to independent. We recommend operating
band 1-4 fully coupled (BAND 1-4 MAXDELTGR = 0) for best stereo image stability.
However, audio-processing experts may want to experiment with lesser amounts of
coupling to achieve a wider, “fatter” stereo image at the cost of some image instability.
The Band 5 compressor/limiter is mainly useful as a de-esser and to prevent high frequency
artifacts when driving low bit rate codecs like the 36 kbps HDC codec used in
the HD AM system. To use the Band 5 compressor/limiter as a de-esser, set the B5
MAXDELTGR to OFF (to allow the channels to be de-essed independently), set the B5
DELTA RELEASE control to +6 (to achieve the fastest possible release), and set the
B4>B5 COUPLING control to 100% (to prevent high frequency energy from building
up excessively).
B5 MAXDELTGR is set OFF most factory presets. This permits band 5 to be used as a
fast-operating de-esser or high frequency limiter that works independently on the