Studio Technologies 220 2004 - Manual (Page 33)

Issue 2, August 2004 Model 220 User Guide
Page 34 Studio Technologies, Inc.
several limitations are taken into account.
The first limitation is that the 10 k ohm
input circuit presents an unbalanced load
to the source. In most cases this shouldn’t
pose a problem. If a balanced intercon-
nection scheme must be maintained an
in-line isolation transformer can be used.
A second limitation is that the audio level
presented must not exceed 0 dBu or
signal “clipping” may occur. Prepare a
3-pin male XLR-type connector so that the
line-level audio source designated as IFB
channel 1 is connected with signal high
on pin 2 and low/shield on pin 1. The
audio source designated as IFB channel
2 should be connected with signal high
on pin 3 and low/shield on pin 1. With
this connection scheme the nominal input
level is –10 dBu, the same as with an IFB
circuit. This may require that an external
attenuator (“pad”) be used to reduce
the level of the connected signal. As
expected, powering the Model 220 in
this scenario will require an external
source of 24 volt DC to be connected.
Additional Connectors
Three spare connector locations are
provided on the Model 220’s back panel.
From the factory they contain blank
plates that can be readily removed and
replaced with a variety of XLR-type con-
nectors. These spare connector locations
are specifically included so that a Model
220 can be customized to meet the many
specific needs that arise in broadcast and
related audio applications. Expected uses
for these locations include adding a 5-, 6-,
or 7-pin XLR-type connector to allow direct
connection of a broadcast headset. Other
uses include creating “loop through” or
“mult” functions for the talkback outputs
or IFB input connections.
The spare connector locations are com-
patible with the Neutrik DL-series of
connectors. For flexibility, versions are
available that provide from three to seven
contacts. For example, a compatible 3-pin
female connector would be Neutrik part
number NC3FD-L-1. To support headsets
the NC6FDS-L-1 is often used. This is a
6-pin female connector with the unique
Switch-craft 6-pin arrangement. The hard-
ware that secures the blank plates to the
Model 220’s back panel is also intended
to secure the replacement connectors.
If connectors are added to the Model
220’s spare connector locations adding
labels to those connectors can be helpful.
For a great look it is recommended that
Brother® P-Touch ¼-inch (6 mm) labels
be created. Tape material that prints white
text on a black background works out
well for the Model 220. The Brother label
cassette number TX-3151, white on black,
is appropriate for use with many of their
printers.
In addition to the spare connector loca-
tions on the back panel, provision has
been made to allow easy interconnection
with the Model 220’s printed-circuit-board-
mounted input and output connectors.
This was accomplished by including
numerous 3-position male “header” con-
nectors on the Model 220’s circuit board.
These headers, on 0.1-inch centers, are
wired in parallel with the Model 220’s con-
nectors. This “no solder” solution makes
customizing a Model 220 a simple pro-
cess. The headers, located on the Model
220’s printed circuit board, are Molex®
part number 22-23-2031. They mate with
Molex housing number 22-01-3037. To
make the interconnection, separate crimp
terminals are attached to loose wires and
then “snapped” into the housing. Molex