Studio Technologies 47 - Manual (Page 9)

Model 47 User Guide Issue 1, August 2010
Studio Technologies, Inc. Page 9
Simple Installation
The Model 47 uses standard 3-pin XLR
connectors to allow convenient intercon-
nection in most broadcast and general
audio environments. For flexibility, access
to the 2-wire party-line intercom interfaces
can be made using the connectors pro-
vided on both the front and back panels.
In permanent installations the back-panel
connectors will typically be utilized. In
other settings, such as field television pro-
duction, front-panel access allows inter-
com belt packs to be rapidly connected,
without requiring access to the inside of a
rack enclosure or necessitating the use of
a secondary input/output (I/O) panel.
The Model 47 is housed in a rugged steel
enclosure that is designed to be “road
tough.” It mounts in one space (1U) of
a standard 19-inch rack enclosure. The
mains input source can range from 100
to 240 volts, 50/60 Hz allowing direct
operation virtually anywhere in the world.
A switch-mode power supply, contained
within the Model 47’s enclosure, provides
conversion of the mains input power into
the DC voltage required by the party-line
power supply circuits. Also contained
within the unit is a DC-to-DC converter
that creates the voltages required by the
analog and digital circuitry. These efficient
power supplies help to ensure cool, reli-
able operation in a variety of settings.
Design Philosophy
While the “bits and pieces” that make up
the Model 47 have been described in con-
ventional terms, the real strength of the
unit rests in how it integrates and performs
in the “real world.” Before beginning the
Model 47’s design process, conversa-
tions with industry experts quickly made
it apparent that installing and configuring
existing 2-wire-to-4-wire interface units was
invariably a time-consuming, aggravating
process that required the talent of an expert
to achieve reasonable results. And even
under those constraints the resulting audio
performance was often mediocre. Any new
design had to look at the application in a
different way. This led to the over-riding
Model 47 design goal: create a “new breed
of cat,” fundamentally changing how broad-
cast 2-wire-to-4-wire interface equipment fit
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
supported with a limited number of configu-
rable choices. 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
the inclusion of multiple LED level meters,
allowing continuous monitoring of the input
and output signals. It also turned out that
in many applications only a small number
of user devices, such as belt packs, are