Studio Technologies 43 - Manual (Page 4)

Model 43 User Guide Issue 1, July 2004
Studio Technologies, Inc. Page 5
Introduction
The Model 43 is designed to create a
broadcast-standard IFB circuit from two
line-level audio sources. The unit will find
use in on-air and production broadcast
applications, as well as specialized applica-
tions such as post-production, recording
studio, and equipment test and mainte-
nance. The Model 43 is a unique and ver-
satile product, providing the resources to
easily create a high-performance “wet” IFB
circuit in a compact, easy-to-use package.
The Model 43’s audio inputs are compatible
with standard line-level audio sources, in-
cluding analog outputs associated with digi-
tal matrix intercom systems. The unit’s IFB
circuit provides DC power and two analog
audio signals to support a range of IFB user
devices. The audio quality is excellent—little
hiss, hum, or other artifacts are present. The
Model 43 is housed in a rugged aluminum
enclosure, making it suitable for permanent
or temporary applications. All inputs and
outputs interface using industry-standard
3-pin male and female XLR-type connec-
tors. The connectors are manufactured by
Neutrik® and feature gold-paled contacts
and metal housings. A source of 24 volts
DC is required for operation. Included with
each unit is an external wall-mount 24 volt
DC power source.
There may be persons not familiar with
the term IFB. That’s not unreasonable as
it’s a somewhat obscure acronym for inter-
rupted foldback. (It can also be known
as interruptible foldback.) On its own, the
term “foldback” is an alternate way of de-
scribing a cue or monitor function. Adding
“interrupted” before it means that the cue
source can be temporarily replaced with
an audio signal originating from a pro-
ducer, director, or other production per-
sonnel. IFB circuits are often used in the
broadcast industry for talent cueing appli-
cations, in both studio and field settings.
Both “dry” and “wet” IFB circuits can be
deployed and their characteristics are
worth reviewing. The term “dry” IFB typi-
cally refers to a transformer-balanced line-
level audio circuit with a +4 dBu nominal
level. This is essentially a standard audio
circuit that is commonly used to intercon-
nect audio equipment. The term “wet” IFB
refers to a circuit that combines DC power
and one or two channels of analog audio.
The audio is unbalanced with a typical
nominal level of –10 dBu. A wet IFB circuit
is the type implemented by the Model 43.
As such, in this user guide the term IFB
will always indicate a wet circuit.
IFB circuits provide an effective means
of delivering power and two channels
View showing 24 volt DC input and IFB circuit
connections
View showing left and right audio inputs