Studio Technologies 230 2008 - Manual (Page 50)

Issue 7, October 2008 Model 230 User Guide
Page 50 Studio Technologies, Inc.
made provision to accomplish this by us-
ing the optional direct microphone output
card. This card, available from Studio
Technologies and purchased separately
(part number 31058), is mounted in a
spare connector location available on the
Model 230’s back panel. With this addi-
tion both an “active” main output and a
“passive” direct microphone output will be
available. Of course, both outputs provide
quiet noise-free on/off (“muting”) control.
The primary application for the direct
microphone output is when the Model 230
is integrated into a system that includes
a high-performance microphone pream-
plifier. This preamplifier may be part of a
stand-alone voice-processor unit, or a mi-
crophone input associated with an audio
console. Engineering personnel may pre-
fer the sonic characteristics of the external
microphone preamp over that of the one
integrated into the Model 230.
It’s important to note that the direct mi-
crophone output card provides a direct
“metallic” path from the microphone input
to the external preamplifier circuitry. It is
not simply an audio “pad” (attenuator) that
reduces the level of the main output from
“line” to “mic.” The Model 230’s auxiliary
relay contacts, along with circuitry on the
direct microphone output card, provide
click-free muting of the signal.
The direct microphone output card con-
tains only passive circuitry. A 3-pin male
XLR-type connector is provided for the
output signal. A resistor and large electro-
lytic capacitor form the muting circuit. This
arrangement allows muting to take place
without disturbing phantom-power that
may be enabled to support a condenser-
type microphone. The direct microphone
output card also contacts two 3-posi-
tion header connectors. These interface
with “headers” on the Model 230’s main
printed circuit board assembly, providing
access to the microphone input connector
and auxiliary relay contact.
The direct microphone output card kit
contains a printed circuit board assembly,
two interconnecting cables, and mounting
hardware. Installing the kit is very simple.
The card’s 3-pin male XLR-type connec-
tor is mounted into one of the three spare
connector locations on the Model 230’s
back panel. Specifically, the connector
location that is closest to the microphone
input connector should be used. The two
screws, with associated locking nuts, are
used to secure the connector and associ-
ated printed circuit board to the enclosure.
The interconnecting cables are then used
to link the card with the Model 230’s main
printed circuit board assembly. One end of
the first interconnecting cable is plugged
into the card’s 3-position header that is
labeled IN. The other end of this cable is
plugged into the 3-position header associ-
ated with the microphone input connector,
labeled P5, located on the main printed
circuit board assembly. One end of the
second interconnecting cable is plugged
into the card’s header that is labeled
RELAY. The other end of this cable is
plugged into the header associated with
the auxiliary relay located on the main
printed circuit board. Additional installa-
tion details are provided in the Additional
Connectors section of the user guide. A
recommended connector labeling method
is also included.
After the direct microphone output card
has been installed, one configuration step
must also be performed. Using the con-
figuration switches, located on the bottom
of the Model 230’s enclosure, the auxiliary
relay control mode must be set to the