Studio Technologies 45A - Manual (Page 9)

Model 45A User Guide Issue 2, November 2011
Studio Technologies, Inc. Page 9
Simple Installation
The Model 45A uses standard 3-pin XLR-
type connectors, allowing convenient 2-wire
party-line and 4-wire interconnection in
broadcast and general audio environments.
For flexibility, access to the 2-wire party-line
intercom interface can be made using
either a male or female XLR connector on
the back panel or a male XLR connector
on the front panel.
In many applications the Model 45A will be
powered by an external source of 24 volts
DC. A compact, lightweight 24 volt DC out-
put power source is supplied with each unit.
The power supply’s universal mains input
capability (100-230 volts, 50/60 Hz) allows
operation virtually anywhere in the world.
The Model 45A can also be powered by the
connected 2-wire party-line intercom circuit.
The four LED meters (previously mentioned)
make it simple to confirm operation of the
connected 4-wire inputs, 4-wire outputs,
and 2-wire party-line circuit. Additional LED
status indicators are also provided, offering
a clear view of the 2-wire DC power source,
auto null functions, and input operating
power.
The Model 45A is housed in a rugged,
lightweight aluminum enclosure that is
designed to be “road tough.” The “1/2-
rack” unit is ready for portable or stand-
alone “thrown-down” applications. Three
rack-mount options are also available allow-
ing one or two units to be mounted in one
space (1U) of a standard 19-inch rack
enclosure or one unit to be mounted in
a special 10.5-inch rack.
Design Philosophy
While the “bits and pieces” that make up
the Model 45A have been described in
conventional terms, the real strength of
the unit rests in the way it integrates and
performs in the “real world.” Studio Tech-
nologies learned from conversations with
industry experts that installing and config-
uring 2-wire-to-4-wire interface equipment
has traditionally been a time-consuming,
aggravating process, requiring the efforts
of an expert to achieve reasonable results.
And even under those constraints the result-
ing audio performance was often mediocre.
This “history lesson” made it clear that any
new design had to start with a unique set
of requirements. This led to an overriding
design goal: create a “new breed of cat,”
fundamentally changing how broadcast
2-wire-to-4-wire interface equipment fits into
actual applications.
An important first step was to eliminate
the requirement that a senior technician,
along with a screwdriver, be present dur-
ing every installation. (It was universally
acknowledged that their time can be better
spent elsewhere!) The need to adjust trim
potentiometers, fabricate special cabling
and connector straps, use nulling ear-
pieces, etc. had to be eliminated. For ex-
ample, in virtually all instances, input and
output levels fall within just a few dB of their
nominal values and, as such, could be sup-
ported with one industry-standard nominal
audio level. In addition, it was acknowl-
edged that in this application analog audio
circuitry was capable of providing excellent
audio performance, but that the required
manual nulling process was operation-
ally taxing. By adding digital control to the
analog circuitry, automatic nulling could be
performed—the best of both worlds!
The next step was to identify resources that
would improve the installation process and
make operation more reliable. This led to