Optimod-AM 9400 V1.2 Operating Manual - Orban

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OPERATION ORBAN MODEL 9400
The curves in the 9400’s equalizer were created by a so-called “minimax”
(“minimize the maximum error,” or “equal-ripple”) IIR digital approximation
to the curves provided by the Orban 622B analog parametric
equalizer. Therefore, unlike less sophisticated digital equalizers that use
the “bilinear transformation” to generate EQ curves, the shapes of the
9400’s curves are not distorted at high frequencies.
Midrange Parametric Equalizer is a parametric equalizer whose boost and cut
curves closely emulate those of an analog parametric equalizer with conventional
bell-shaped curves.
MID FREQ determines the center frequency of the equalization, in Hertz.
Range is 250-6000Hz.
MID GAIN determines the amount of peak boost or cut (in dB) over a
10 dB range.
MID WIDTH determines the bandwidth of the equalization, in octaves.
The range is 0.8-4.0 octaves. If you are unfamiliar with using a parametric
equalizer, 1 octave is a good starting point.
The audible effect of the midrange equalizer is closely associated with the amount
of gain reduction in the midrange bands. With small amounts of gain reduction, it
boosts power in the presence region. This can increase the loudness of such material
substantially. As you increase the gain reduction in the midrange bands (by turning
the MULTIBAND DRIVE (Multiband Drive) control up), the MID GAIN control will have
progressively less audible effect. The compressor for the midrange bands will tend to
reduce the effect of the MID frequency boost (in an attempt to keep the gain constant)
to prevent excessive stridency in program material that already has a great
deal of presence power. Therefore, with large amounts of gain reduction, the density
of presence region energy will be increased more than will the level of energy in
that region.
Use the mid frequency equalizer with caution. Excessive presence boost tends to be
audibly strident and fatiguing. Moreover, the sound quality, although loud, can be
very irritating. We suggest a maximum of 3 dB boost, although 10 dB is achievable.
In some of our factory music presets, we use 3 dB boost at 2.6 kHz to bring vocals
more up-front.
High Frequency Parametric Equalizer is a parametric equalizer whose boost and
cut curves closely emulate those of an analog parametric equalizer with conventional
bell-shaped curves.
HIGH FREQ determines the center frequency of the equalization, in
Hertz. The range is 1-15 kHz.
HIGH GAIN determines the amount of peak boost or cut over a 10 dB
range.
HIGH WIDTH determines the bandwidth of the equalization, in octaves.
The range is 0.8-4.0 octaves. If you are unfamiliar with using a parametric
equalizer, one octave is a good starting point.
Excessive high frequency boost can exaggerate hiss and distortion in program material
that is less than perfectly clean. We suggest no more than 4 dB boost as a practi-