Studio Technologies 2A 2013 - Manual (Page 25)

Model 2A User Guide Issue 1, October 2013
Studio Technologies, Inc. Page 25
LED, labeled STD, is lit whenever the inter-
face is set for the standard audio mode by
the switch on the back panel. The red LED,
labeled RING/LC indicates two conditions.
It will flash rapidly when the interface is set
for telephone line mode and ringing energy
is detected on the telephone line. It will light
continuously any time the interface is set
for the telephone line mode and DC current
is flowing through the interface. DC current
flowing would, of course, indicate that the
telephone line is off hook and is being con-
trolled by the Model 2A.
The interface control switch, active in the
telephone line mode, allows the interface
to be answered (taken “off hook”) or hung
up (placed “on hook”). Momentarily press-
ing the switch to its up position, labeled
ANSWER, places the interface in its active
or off-hook state. If loop current is detected,
the interface will stay in its off-hook state
and the loop current LED will light. If loop
current is not detected, the interface will
return to its on-hook (idle) state after a few
seconds. Momentarily pressing the switch
to down position, labeled HANG UP, dis-
connects the interface from the telephone
line.
A second switch controls the audio routing
through telephone interface 2. In the center
position, labeled RCV, audio is received
from telephone line 2. In the up position,
labeled SEND CH1, IFB channel 1 audio
(program and interrupt audio) is sent out
the interface. In the down position, labeled
SEND CH2, IFB channel 2 audio (program
and interrupt audio) is sent out the inter-
face. The overall send level is not adjust-
able. Just like the talent amplifier and line
outputs, the interrupt level is fixed and
the program level is adjusted in reference
to it. The send level has been internally
configured to give the highest signal level
possible without overloading the telephone
company equipment.
On interface 2 a level trim pot is also
provided allowing the receive audio to be
adjusted over a ±8 dB range. A quiet signal
can be boosted and a “hot” signal can be
attenuated. The trim pot is accessible via a
small hole in the front panel, directly to the
right of the routing control switch. Using
an Xcelite® “greenie” straight-blade screw
driver is recommended. Note that the trim
pot is active only in the receive mode.
Monitor Output
A level control and source select switch is
associated with the monitor output section.
The level control adjusts the output level
sent to the monitor speaker output. IFB
channel 1 is monitored when the source
select switch is in its up position. In its
down position, channel 2 is monitored.
The middle position is labeled OFF and
the monitor amplifier is, as you might
guess, off!
Applying Power
Upon mains power being applied to the
Model 2A the unit will go through a power-
up sequence that will light all of the meter
and status LEDs in a test pattern. Then
the levels meters are used to momentarily
display the version number of the internal
firmware (embedded software that runs
in a microcontroller integrated circuit).
The meter associated with channel 1 will
display the major version number with
a range of 1 to 5 starting at the bottom
LED and moving up. The meter associated
with channel 2 will display the minor
version number, also with a range of 1
to 5. The version number will display for