Manual

Model 45DC User Guide Issue 3, March 2016
Studio Technologies, Inc. Page 13
Party-Line Active Detection
Function
When local power has been selected for
a Model 45DC party-line interface and
switch SW2 is in its off (down) position a
minimum of approximately 5 mA of current
must be drawn from that interface for an
“active” condition to be recognized. When
this condition is met the associated active
LED on the front panel will light and the
Dante output audio path will be active. This
default setting is appropriate for most ap-
plications and helps to maintain the most
stable audio performance.
Switch SW2 allows the party-line active
detection function to be disabled. When
SW2 is in its on (up) position no minimum
party-line current draw is required for the
active LED to be lit and an output audio
path to be active. Only in special situations
would the function need to be disabled.
One example is the case where a Model
45DC is being used with a Telex® BTR-700
Wireless Intercom System. The BTR-700 is
designed to directly interface with a party-
line intercom circuit. This circuit would
typically have DC power and one audio
channel that has a terminating impedance
of nominally 200 ohms. The Model 45DC
can provide two such circuits when the
local power functions are enabled. But a
problem arises as the BTR-700 does not
draw current from the connected inter-
com circuit. It doesn’t function in the same
manner as would a typical beltpack, in-
stead using an external source of power
for operation. So in this case the Model
45DC’s party-line interface would not sup-
ply current, the active LED would not light,
and the output audio path would not be
enabled. Users of the BTR-700 would be
able to hear Model 45DC input audio but
not send audio out the Dante interface.
Disabling the party-line active detection
function by placing SW2 to its on (up) posi-
tion would resolve this issue. Even though
no DC current would be supplied by the
Model 45DC successful operation would
take place.
When the Model 45DC has been set to
not provide local power the party-line
active detection function works in a slightly
different way. Only if a DC voltage of ap-
proximately 18 or greater is present on
pin 2 will the party-line interface recognize
that a valid interconnection is present. In
this case the active LED will light and the
Dante output audio path will be active.
When SW2 is in its on (up) position the
party-line active detection function will be
disabled and monitoring of DC voltage on
pin 2 will not take place. In this situation
the active LED will always be lit and the
output audio path will be active. As of the
writing of this guide the practical applica-
tion of this specific configuration has not
been determined. But it’s ready should the
need arise!
Dante Configuration
To integrate the Model 45DC into an ap-
plication a number of Dante-related param-
eters can be configured. At a minimum, the
Figure 4. Party-line active detection function
configuration switch