Issue 5, April 1994
Mic-PreEminence User Guide
Page 10
Studio Technologies, Inc.
Balanced Operation
In many cases, users of the Mic-Pre-
Eminence will be connecting the balanced
outputs to the balanced inputs on another
piece of equipment. The output select
switches should be set to the BAL position.
In this case the output stage is capable of
a +30dBu (+29dBu into 600 ohms) signal
level before clipping.
Unbalanced Operation
In some applications, the unbalanced
line outputs will be used to link the
Mic-PreEminence with “–10” unbalanced
inputs on another piece of equipment.
Placing the output select switches to the
UNBAL position disconnects the output
circuitry from the 3-pin XLR-type connectors
and connects it via “pads” to the ¼-inch,
2-conductor output connectors.
Technical Notes
Capacitors in the Mic-PreEminence
When designing the Mic-PreEminence,
Studio Technologies, Inc. tried to incorpo-
rate all sonic improvements that are
practical from a cost and implementation
standpoint. The design we implemented
requires a minimum number of audio
coupling capacitors. An explanation of their
purpose and possible substitution follows.
As the Mic-PreEminence contains two
identical channels, all references will be
made to one of the channels. Please refer
to the schematic diagrams at the end of this
manual while studying this section.
Input Capacitors
The microphone input is capacitor coupled
to the input stage to block phantom power
that may have been selected. The 100uf
electrolytic capacitors used in this location
are a low leakage type. You could rightfully
say that the capacitors are not required if
phantom power is switched off, but in most
cases (we realize not all) phantom power
will be used. In the case where phantom
power is off, the capacitors still prevent
stray DC from possibly “blowing up” the
input section. There are really no cases
where eliminating or shunting the input
capacitor pairs is recommended.
Interstage Capacitors
As the circuit is for all intents and purposes
balanced throughout, two capacitor pairs
are required to couple the input stage to the
output stage. These capacitors are required
to prevent normal DC in the input stage
from affecting the output DC balance adjust-
ment. The capacitor pairs consist of a 100uf
electrolytic type in parallel with a 0.33uf
stacked, metallized film type. Removing
or shunting these capacitors should not
be performed.
Output Coupling
As shipped from the factory, the line output
circuits are directly coupled to the output
connectors. This has been accomplished
by shunting the output capacitors, which are
the same type and value as the interstage
capacitor pairs, by soldering 0 ohm resistor
jumper wires into the Mic-PreEminence
circuit board. This direct coupling provides
the best sonic performance. A small DC
voltage, typically not exceeding 100 milli-
volts, may be found on the line outputs due
