User Guide

Model 354 User Guide Issue Preliminary 1, August 2021
Studio Technologies, Inc. Page 9
Model 354
TALK STATION
unidirectional, electret microphone was designed spe-
cifically to maximize voice reproduction in intercom,
voice paging, and related applications. To minimize
the impact of breath noise, a foam windscreen is
included with each GME-3-12.
From the factory a plastic hole plug is pressed into
the Model 354’s gooseneck bushing. This protects the
connector and internal circuitry from having undesir
-
able material such as dirt, dust, or foreign objects
enter the unit. The plastic plug should be removed
and stored prior to the gooseneck microphone being
installed. Typically, a tool isn’t required to lift the edge
of the hole plug from the bushing; the hole plug can
be removed using one’s fingers. Once the bushing is
free of the plastic hole plug, a compatible gooseneck
microphone can be inserted and secured using the
threaded interconnect. Tighten the microphone to the
bushing by hand, turning it in the clockwise direction.
Hand-tighten it until a secure connection has been
made. Do not use a tool to tighten the microphone!
It’s possible that a microphone won’t be needed. This
would be in the rare case where the Model 354’s
ability to play audio files is the only function that is
required. In this odd but possible case, a gooseneck
microphone would not be required.
The two main requirements for a compatible goose
-
neck microphone are 1) that it contain an electret mi-
crophone capsule and 2) it interconnects by way of a
1/4-inch 3-conductor plug with an integrated threaded
bushing with pitch of 7/16-20 UNF. The RTS®/Telex®/
Bosch® MCP-90-series of gooseneck microphones
should be directly compatible with the Model 354 and
will perform acceptably. Gooseneck microphones
from other sources such as Clear-Com® may also be
utilized. But known-excellent performance would be
obtained using the aforementioned GME-3-12.
The 3-conductor 1/4-inch jack associated with the
Model 354’s gooseneck bushing has a tip connection
that is used for microphone audio as well as to sup
-
plying the low-voltage DC needed for powering the
electret microphone. (The power source is 3.3 volts
DC in series with a 2.49 k resistor.) The ring connec-
tion is used for the microphone’s low signal (audio and
DC).The sleeve connection is chassis ground and isn’t
used as a signal conductor. (Although it does play an
important role is shielding the microphone assembly.)
Within the Model 354’s circuitry the ring and sleeve
connections are connected together as well as being
connected (“tied”) to the chassis.
The Model 354’s gooseneck bushing includes a hex-
head socket set screw with a thread pitch of 4-40
UNC. This allows the gooseneck microphone to be
secured into the bushing by simply tightening the set
screw against the microphone using a 5/64-inch hex
driver. In many cases, especially in applications where
the Model 354 will be moved from venue-to-venue, it
may not be optimal for the hex screw to be utilized.
This is because the gooseneck microphone may need
to be removed and stored for transit. In this case, the
set screw should be removed and stored.
Analog Monitor Output
The Model 354’s analog monitor output, accessible
by way of a 3-pin male XLR connector located on the
back panel, is designed to connect to a variety of de-
vices. It’s expected that in many situations the analog
monitor output will be utilized for local audio monitor-
ing. The simplest means to accomplish this is to use
a loudspeaker with an internal amplifier, such as a
model from the popular Fostex® 6301-series. Other
applications may connect the analog monitor output to
the input of an audio power amplifier associated with
a loudspeaker. And, depending on how the Model 354
is configured using the STcontroller application, the
analog monitor output can also be useful in a number
of general-purpose audio monitoring applications.
The Model 354’s analog monitor output is line-level,
electronically balanced, and capacitor coupled. It can
correctly interface with balanced or unbalanced loads
of 2 k (2000) ohms or greater. A configuration setting
in the STcontroller application is used to select how
the analog monitor output will function from among
three operating modes. In the Adjustable (Post-Fader)
mode the level of the analog monitor output will be
dependent upon the setting of the front-panel level
control. (A level control is also be known in the audio
world as a “fader.” “Post” indicates that the monitor
output will obtain its audio source after (“post”) the
level control.)
When selected for the Fixed –10 (Pre-Fader) mode
the analog monitor output will have a fixed nominal
output level of –10 dBu. In this mode, the nominal
output level has been optimized to match the input
sensitivity typically found on amplified loudspeak
-
ers. Since most amplified loudspeakers contain an