Studio Technologies 48 - Manual (Page 11)

Issue 1, October 2000 Model 48 User Guide
Page 12 Studio Technologies, Inc.
jack, but with a unique connection
scheme. Pins 3 and 4 are associated with
the telephone signal, and pins 2 and 5
select the “wet” or “dry” operating mode.
When pins 2 and 5 are not shorted (left
open or “floating”) the interface is in the
“wet” mode. When pins 2 and 5 are de-
tected as being shorted (connected to-
gether) the “dry” mode is activated.
The Model 48 can be configured to auto-
matically select the operating mode of the
Model 770’s telephone interface. To sup-
port this is quite simple. One of the Model
48’s destinations is selected to serve as
the telephone line source for the Model
770. A standard modular cable, with at
least four connections implemented, is
used to link the Model 48’s destination
jack with the Model 770’s telephone jack.
The unique part of the installation involves
the Model 48’s source (input) connections.
“Wet” sources are connected to the Model
48 with pins 3 and 4 carrying the tele-
phone signal and pins 2 and 5 are not
shorted (left open). “Dry” sources are
connected in this manner: with pins 3 and
4 carrying the dry audio signal and pins 2
and 5 shorted (connected together).
Shorting pins 2 and 5 has identified that
this specific source is “dry.”
When this arrangement is used, the Model
770’s telephone interface will automatically
“know” what type of telephone line the
Model 48 has selected. Whenever a “dry”
signal is selected, pins 2 and 5 on the
Model 770’s telephone interface jack will
be placed in the shorted condition. This
will cause the telephone interface circuitry
to operate in the “dry” mode. If a “wet”
signal is selected pins 2 and 5 are not
shorted (left open).
Audio Signals
It’s possible to utilize the Model 48 to
route line-level audio signals. As the
sources (inputs) and destinations (out-
puts) support two telephone lines they
can also support one stereo audio (4-wire)
signal. Should audio signals be con-
nected, care must be taken to ensure that
the input-to-output polarity is maintained.
As previously noted, the Model 48’s
source (input) and destination (output)
jacks are designed to interface using
standard reversing modular telephone
cables. This design requires that care be
taken when interconnecting audio signals.
General-Purpose Signals
The Model 48 can be used to route low-
voltage, low-current signals for special
applications. Each source (input) and
destination (output) can support connec-
tion of up to four signal lines. Ensure that
the reversing action of the sources (inputs)
versus the destinations (outputs) is ac-
counted for in the interconnecting wiring.
The rating of the mechanical switches
limits the controlled signals to a maximum
of 0.1A and 30V.
Operation
Now that the earth ground, source, and
destination connections have been made
the Model 48 can be placed into service.
As expected, operation is very simple.
Associated with each of the five destina-
tions is a group of six push-button
switches. Any one of the six possible
sources can be selected to connect to
a specific destination. Note that the six
switches associated with a group are