User manual

C4-TOP (2.0E)
C4-TOP
HFC
GRISP
MUTE
OVL
-12 dB
-6
+6
0
Controls on C4-TOP
controller module
Frequency response correction of HFC circuit
20
100
1k
10k
20k
2
0
4
6
-2
-4
dB
C4-TOP/SUB stacks with B2-SUB
C4-TOP controller module switches
HFC switch & indicator
In HFC mode (High Frequency Compensation, yellow HFC LED
illuminated), the response of the system is tailored for remote
listening positions. The characteristics of HFC mode are detailed in
the graph below right.
Selecting the HFC switch compensates for loss of high frequency
energy due to absorption in air when loudspeakers are used to
cover far field listening postions. The HFC correction equates to the
HF loss which occurs at a distance of 30 m (100 ft) at 20° C (68° F)
in 70% relative humidity.
In applications which use vertically arrayed C4-TOP cabinets,
ground stacked or flown, the HFC switch should be used selectively,
only for those cabinets covering the far field. This guarantees the
correct sound balance between close and remote audience areas,
whilst all mainframes driving the array can be fed with the same
signal.
Operation with E-PAC (only possible with E-PAC
version 3 with display)
To drive C4-TOP cabinets the E-PAC has to be configured to
C4-TOP mode.
For an E-PAC version 3, the configuration is set via a front panel
digital rotary encoder in conjunction with an LCD.
The HFC setting is available. The characteristics of the HFC setting
are explained on the previous page under the section "C4-TOP
controller module switches".
The E-PAC can drive a single C4-TOP cabinet at an output power
of 300 watts. LO IMP mode allows the E-PAC to drive two C4-TOP
cabinets with a 6 dB reduction of input level to the speakers.
C4 arrays
The horizontal angle between adjacent C4-TOP's in an array can
be set to between 20° and 30°. Using the 30° maximum horizontal
array angle produces arrays with (n x 30°) + 10° horizontal
coverage - where n = the number of speaker columns in the array
- in the case of a four column array this results in 130° of
horizontal coverage. Smaller angles between the cabinets will give
a smaller horizontal coverage area but will produce higher sound
pressure on the array middle axis.
Especially in venues with difficult room acoustics the configuration
of the array should be thoroughly adapted to the actual
requirements. In order to keep diffuse sound low, the total
coverage angle should only be as wide as necessary to cover the
audience area.
In a typical left-right set up it is sufficient if the coverage zones of
the two PA wings or rigs overlap only in the middle of the room.
Because of the differences in arrival time, large set ups allow
stereo imaging only on the middle axis between both arrays.