HFC circuit
Fig. 4: Frequency response correction of
HFC circuit, HF1 and HF2 settings
Selecting the HFC (High Frequency Compensation) circuit compensates
for loss of high frequency energy due to absorption in air when
loudspeakers are used to cover far field listening positions.
The HFC circuit has two settings (HF1, HF2) for different distance ranges
the cabinets have to cover. The settings should be used selectively, only
for those cabinets covering the respective distances, HF1 for distances
larger than 40 m (130 ft) and HF2 for 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.
Using the HFC function provides the correct sound balance between
close and remote audience areas, whilst all amplifiers driving the array
can be fed with the same signal.
CPL circuit
Fig. 5: Frequency response correction of
CPL circuit
The CPL (Coupling) circuit compensates for coupling effects between the
cabinets by reducing the low and mid frequency level. The CPL function
should be used 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.
The function of the J12 CPL circuit in the D12 amplifier is shown in the
diagram opposite. Please note that all cabinets within the line array
should be operated with the same CPL setting.
Dispersion characteristics
The graph below shows dispersion angle over frequency plotted using
lines of equal sound pressure (isobars) at –6 dB and –12 dB. The
nominal horizontal dispersion of 120° is maintained above 200 Hz.
Fig. 6: Isobar diagram J12 horizontal
J12 Manual
(1.2 EN)
Page 6 of 8
Содержание J12
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