Model 46A User Guide
Issue 1, September 2014
Studio Technologies, Inc.
Page 17
switch is in its on (up) position the nominal
level is –10 dBu. This setting is appropriate
when beltpacks from RTS, such as the BP-
325, or listen-only talent amplifier units from
Studio Technologies, Inc. are connected.
For best Model 46A performance it’s impor-
tant that the 2-wire nominal level selection
be made correctly.
4-Wire Nominal Audio Level
DIP switches 3 and 4 are used to configure
the nominal level of the input and output
circuitry associated with interface 1’s two
4-wire input and output connections. Four
level settings are available: 0, +4, +6, and
+8 dBu. Prior to setting these DIP switches
it’s important to determine the nominal au-
dio level of the equipment connected to the
Model 46A’s 4-wire input and outputs. This
may take a little investigation but is impor-
tant for obtaining the best possible Model
46A performance.
The 0 dBu setting is provided specifically
for use when a Model 46A is intercon-
nected with a Clear-Com matrix intercom
system. The +4 dBu setting is appropriate
when standard audio lines with “+4” nomi-
nal levels are interconnected. The +6 dBu
setting can be appropriate when intercon-
necting with equipment manufactured in
Europe, such as the digital matrix intercom
systems from Riedel. The +8 dBu setting is
provided specifically when interconnecting
the Model 46A with audio signals associ-
ated with an RTS ADAM-Series of matrix
intercom system. This includes the related
RVON-I/O unit.
When DIP switches 3 and 4 are in their off
(down) position the nominal level is set for
0 dBu. When switch 3 is on (up) and switch
4 is off (down) the nominal level is +4 dBu.
When switch 3 is off (down) and switch 4 is
on (up) the nominal level is +6 dBu. When
both switches 3 and 4 are in their on (up)
position the nominal level is configured for
+8 dBu.
Advanced
Configuration
Four DIP switches are provided on the
Model 46A’s back panel. Note that switch-
es 1, 2, and 4 are utilized; switch 3 is not
used. They allow the two interfaces to be
configured for several advanced operat-
ing modes. Refer to Figure 6 for a detailed
view of these DIP switches. The available
configurations include auto terminate, auto
null button operation, and factory test.
Figure 6. Detail of back panel showing the
Advanced Mode DIP switches
Auto Terminate
The auto terminate function is designed to
ensure that each 2-wire-to-4-wire interface
circuit remains stable under most oper-
ating conditions. Specifically, 200 ohm
impedances are automatically applied to
both pins 2 and 3 of a Model 46A 2-wire
party-line interface when that interface is
configured for external power and no ex-
ternal source of intercom power is detect-
ed on pins 2 or 3. This function is directly
compatible with RTS TW-Series intercom
