Studio Technologies 2A 2015 - Manual (Page 26)

Issue 2, March 2015 Model 2A User Guide
Page 26 Studio Technologies, Inc.
set for the telephone line mode and DC
current is flowing through the interface.
The interface control switch, active only
in the telephone line mode, allows the
interface to be answered (taken “off hook”)
or hung up (placed “on hook”). Momentari-
ly pressing 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 off-hook (idle)
state after a few seconds. Momentarily
pressing the switch to the down position,
labeled HANG UP, immediately discon-
nects the interface from the telephone line.
Telephone line audio signals can vary
greatly in level on a call-by-call basis.
To counter this problem, a level trim poten-
tiometer is provided for the operator, allow-
ing adjustment 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
interface control switch. Using an Xcelite®
“greenie” straight-blade screw driver is
recommended.
Telephone Interface 2
Two status LEDs, two switches, and one
trim potentiometer are associated with
telephone interface 2, labeled TELCO 2.
The yellow LED, labeled STD, is lit when-
ever the interface 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 rap-
idly when the interface is set for telephone
line mode and ringing energy is detected
on the telephone line. It will light continu-
ously 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 de-
tected, 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,
disconnects the interface from the tele-
phone 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