The applicable amplifiers provide two setups ("Arc" or "Line") for
the J8 and J12 loudspeakers. These are available in 2-Way Active
mode.
Arc and Line setups
The selection of Arc or Line depends on the curvature of the array.
Both setups may be used within one array.
The Arc setup is intended for line array loudspeakers when used in
curved array sections.
The Line setup is used for long throw array sections with three or
more consecutive splay settings of 0° or 1°. Compared to the Arc
setup, the mid/high range is reduced to compensate for the
extended nearfield.
The transition from Line to Arc configuration within the array is
made according to the splay progression but may allow for certain
deviations due to the wiring of the cabinets in groups of up to two.
2.3.1. Controller settings
For acoustic adjustment the functions CUT, CPL and HFC can be
selected.
CUT mode
Set to CUT, the low frequency level of the cabinets is reduced. The
J8/J12 array is now configured for use with the d&b J-SUB or
subwoofers.
CPL function
The CPL (Coupling) circuit compensates for coupling effects
between the cabinets by reducing the low and mid frequency level.
The CPL function should be selected when J8/J12 cabinets are
used in arrays of five or more.
As coupling effects increase with the length of the line array, the
CPL circuit can be set to dB attenuation values between 0 and –9.
CPL begins gradually at 2 kHz, with the maximum attenuation
below 100 Hz. With higher attenuation values the corner
frequency of the filter shifts towards lower values.
Note: The CPL function is shown in the diagram opposite.
Please note that all cabinets within the line array should be
operated with the same CPL setting.
HFC function
Selecting the HFC (High Frequency Compensation) function
compensates for the loss of high frequency energy due to air
absorption when loudspeakers are used to cover far field listening
positions.
The HFC function has two settings (HFC1 and HFC2) for different
distances the cabinets need to cover. The settings should be used
selectively; HFC1 for cabinets covering distances larger than 40 m
(130 ft) and HFC2 for those covering distances larger than 80 m
(260 ft).
The compensation is adjusted for a typical relative humidity of
40 %. With lower humidity the absorption by air increases
therefore the distances where the respective HFC setting provides a
correct equalization are shorter than indicated above.
Frequency response correction of the CPL function
Frequency response correction of the HFC function
d&b J8/J12 Manual 2.2 en 7
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