Studio Technologies 2A 2013 - Manual (Page 18)

Issue 1, October 2013 Model 2A User Guide
Page 18 Studio Technologies, Inc.
runs longer than 500 feet are possible but
should be carefully checked for correct
operation.
It’s come to the factory’s attention that some
installers have been effectively using stan-
dard Ethernet cables to link Model 22 units
with Model 2A units. They start by using
adapters that convert 9-pin D-subminiature
connectors to RJ45 (8-pin module) jacks.
Then they select or create standard Ether-
net cables to support the cable “run.” There
is one downside in that these cables will
only support eight signals and not the com-
plete nine used by the Model 22 and Model
2A. Physical pins 1-8 will be connected but
not pin 9. This will implement all functions
except the Model 22’s ability to mute the
Model 2A’s monitor speaker output. This
is because pin 9 of the D-subminiature
connector enabled this function. If the instal-
lation doesn’t require muting of the monitor
output speaker in response to Model 22
IFB activity then this installation may prove
worthwhile.
Talk Audio Source
A source of talk audio must be connected
to the Model 22. A gooseneck microphone,
available as an option from Studio Technolo-
gies, will often be used with a Model 22.
Alternately, a source of line-level audio can
be connected. A 5-position screw terminal
strip is used to connect signals to the mic
and line inputs. The mic input is configured
only for use with unbalanced electret
microphones. The + terminal on the mic
input provides current limited 5 volts DC
to power the electret microphone. The –
terminal is connected to the microphone’s
low signal lead. The connection marked
SHLD is intended for the shield wire of the
microphone cable; it doesn’t carry signal.
The Studio Technologies’ Model 11A
Gooseneck Microphone is an unbalanced
electret type, requiring an external source
of DC power. The microphone utilizes a
¼-inch 3-conductor plug for interconnec-
tion. The tip lead brings DC power to the
microphone, as well as having microphone
audio superimposed on it. The ring lead is
microphone common. The sleeve lead is a
shield connection.
Included with the Model 11A is a mounting
hardware kit. This kit contains a ¼-inch
3-conductor jack used to mate with
the microphone’s plug. At the factory a
3-conductor wiring harness assembly is
attached to the jack. The wiring harness
has a red-colored wire, a black-colored
wire, and a shield wire. One end of the
red wire is attached at the factory to the
tip connection on the jack. The other end
should be connected to the + terminal on
the Model 22’s terminal strip. One end of
the black-colored wire is attached at the
factory to the ring lead of the jack. The oth-
er end should be attached to the – terminal
on the terminal strip. One end of the shield
connection is attached at the factory to the
sleeve of the jack. The other end should
be attached to the SHLD terminal on the
Model 22’s terminal strip. It’s important to
note that a dynamic microphone must not
be connected to the mic terminals; it won’t
provide the correct signal level and dam-
age to the mic may occur.
An external source of talkback audio can
be connected to the Model 22’s terminal
strip. A possible source of this audio would
be a “hot mic” output of an intercom user
station. The line input circuit is electroni-
cally balanced, capacitor coupled, with an
input impedance of 24 k ohms. Balanced
or unbalanced signals can be connected.