9762A
– Preamplifier
Owner’s Manual
Page 15
RTZ Professional Audio
Jumper JP3 allows for three configuration options for the +48V LED on
the front panel as shown in the following table.
Table 4
– JP3 Front Panel 48V LED Configuration Options
Mode
JP3
Description
Auto
1 & 2
48V LED glows if the +48V phantom power
switch is enabled or the unit if being “back fed”
48V from another microphone input source
through a microphone splitter or other external
source.
ON
2 & 3
The 48V LED only lights if the +48V phantom
power switch is enabled. The LED will not light
even if the unit is being “back fed” phantom
power into the microphone input from another
source.
OFF
(none)
The 48V will never light regardless of whether or
not phantom is being applied internally or
externally.
The 9762A ships with the 48V LED configured for “Auto” (pins 1 & 2)
mode as the default mode operation. This is the preferred mode of
operation in most cases and the 48V LED will indicate the presence of
phantom power either internally by 9762A or externally from another
source.
Note that you can completely disable the phantom power and LED via
JP3 and the S1 DIP switch. The 48V LED can be disabled via JP3 and
the power can be disabled via S1 such that all phantom power and
features are disabled. Thus, the preamp can never apply phantom power
to a microphone and the 48V LED and front panel switch are effectively
disabled. These features allow you to dedicate the preamp module for
use with non-phantom microphones if desired.
When S1 is used to defeat the possibility of phantom powering, it also
disconnects the phantom feed resistors from the input wiring, resulting in
the highest possible input impedance at the microphone input. This is the
preferable way to use the preamp with ribbon microphones, however you
may need the ability to use the 9762A with either type, in which case
leaving S1 set for phantom powering is the proper option.
S1 is mounted somewhat internally to the module, and is not really
meant to have its setting changed frequently. This causes wear to the
edge connector contacts, which was not meant for frequent mate/unmate
cycles.
