Issue 5, April 1994
Mic-PreEminence User Guide
Page 8
Studio Technologies, Inc.
line output connectors are male, and the
unbalanced output connectors are female.
The Mic-PreEminence conforms to the
world standard for 3-pin audio connectors:
pin 1 shield, pin 2 signal high, pin 3 signal
low. This standard is especially applicable
for the Mic-PreEminence as most recording
studio quality microphones conform to this
standard. Pin 1 on the four XLR-type audio
connectors and the sleeves of the two
¼-inch, 2-conductor jacks are connected in
common with power supply common, chas-
sis ground, and power cord ground.
Operation
Using the Controls and Meters
There are five switches and two gain
controls on the front panel of the Mic-Pre-
Eminence. There are two switches on the
back panel.
Power Switch
The power switch controls the AC mains
to the unit. Power can be applied to the
Mic-PreEminence continuously without
adverse effects. Energy conservation
practices dictate applying power only as
required; think green! When power is
switched on or off, high level audio “pops”
on the output connectors are likely. This is
a function of the DC power sources turning
on or off to the Mic-PreEminence circuitry.
Care must be taken to ensure that these
“pops” do not damage equipment or ears
associated with the Mic-PreEminence
outputs.
Phantom Power Switches
Each channel contains a phantom power
switch. When this switch is in the ON
position, +48Vdc is applied via 6.81k ohm
resistors to pins 2 and 3 of the associated
microphone input connector. This +48Vdc
power should allow virtually all phantom
powered microphones to work correctly.
Microphones that require high start-up
current, such as the Neumann TLM 170,
will operate correctly. When using micro-
phones that do not require phantom power,
the phantom power switch should be left in
the OFF position. When phantom power is
switched on or off, high level audio “pops,”
several seconds of hissing noise, or other
strange sonic gyrations on the line outputs
are possible. Care must be taken to ensure
that these noises do not damage equip-
ment or ears associated with the Mic-Pre-
Eminence line outputs. The level meter
LEDs will light for a few seconds when
applying or removing phantom power. This
is due to leakage current coupled through
the input capacitors to the input semicon-
ductors. This is completely normal and does
not indicate any Mic-PreEminence prob-
lems. After the current dissipates, the lights
resume their normal function and the nor-
mal sonic cleanliness returns.
Output Phase Switches
The output phase switch associated with
each channel reverses the relative phase
(input versus output) of both the balanced
and unbalanced outputs. For the balanced
output the switch reverses the connections
to pins 2 and 3 of the output connector.
For the unbalanced output the switch
changes the point in the circuitry where the
unbalanced output obtains its signal. In the
