Crown VFX2 Instruction Manual page 15

The use of the VFX2 controls in the different modes of
operation available is described in the following
paragraphs.
2.5.1 Control Functions
Although the uses and possible applications of the
VFX2 are almost unlimited, the operation of the
controls is quite simple. In addition to the POWER
switch, there are only four types of controls:
Attenuator (LEVEL), Mode, Range and Vernier. One
attenuator (screwdriver-adjusted pot) and one mode
switch are provided on the rear panel for each
channel. One range and one vernier switch for each
of the four filters are provided on the front panel. A
simplified, functional block diagram is located on the
rear panel of the VFX2 to aid in understanding the
operation of the unit. This block diagram is also
shown in Figure 2-6.
a. INPUT LEVEL (Attenuator)
The attenuators are screwdriver adjustments
located on the rear panel. Each attenuator controls
the gain of the adjacent (BALANCED) input. With the
input attenuator fully CW, a maximum gain of 15.5
dB is obtained. Minimum gain is unity at full
attenuation, fully CCW. The input impedance of the
(BALANCED) input is independent of the attenuator
(gain) setting.
b. MODE Switch
Two mode switches, one for each channel, are
located in the center of the rear panel. These two-
position, slide switches are labeled LOW PASS —
BANDPASS. This switch determines the source of
the input signal for the low pass filter stage. Set to
LOW PASS, the input signal is selected directly from
the input. Set to BANDPASS, the input signal is
selected directly after the high pass filter stage. The
mode switch affects only the LOW PASS outputs,
adjacent to the power transformer on the rear panel.
c. RANGE and VERNIER Controls
Four pairs of controls for the four filter sections are
located on the front panel. These include one
VERNIER potentiometer, and one RANGE switch for
each High Pass and Low Pass filter. The controls are
used to set the (3 dB) corner frequency for the filters.
The VERNIER potentiometer selects the first
significant digit (2 to 20) of the selected frequency;
the four-position RANGE switch (OFF-X10-X100-
X1K) selects the appropriate multiplier.
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d. POWER Switch
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