Studio Technologies IFB Plus 2005 - Manual (Page 6)

Issue 8, December 2005 Model 2 User Guide
Page 6 Studio Technologies, Inc.
Model 2 Central Controller
Contained in a single rack space unit is ev-
erything required to implement a 2-channel
IFB system. Features include multiple pro-
gram inputs, telephone interfaces, voice-
operated (VOX) interrupt, level meters, mon-
itor amplifier, and internal interrupt micro-
phone. Up to four Model 22 Access Stations
can be connected to the Model 2, allowing
producer or director positions to access the
IFB channels. In addition, up to four Model
32 or Model 33 Talent Amplifiers can be con-
nected to a Model 2. The Model 32 and 33
allow personnel access to the IFB channels
using a single standard microphone cable.
The Model 2 packs numerous features
into a single, 19-inch rack space. Standard
connectors are used throughout, including
3-pin XLR-type, ¼-inch 2-conductor,
9-position D-subminiature, and modular
telephone (RJ11-type) jacks. Power is sup-
plied by standard 120 or 220/240 V (factory
configured), 50/60 Hz via a detachable cord.
IFB Channels
The Model 2 contains two independent
IFB channels. Each channel has individual
controls and indicators, including program
source select switches, program level con-
trol, 5-segment LED level meter, and LED
status indicators. We’ll describe one channel
in this paragraph. Six switches allow the four
program inputs and incoming audio from
the two telephone interfaces to be selected
as program audio. A level control allows
adjustment of the program audio level
relative to the fixed interrupt audio level.
A 5-segment LED level meter displays the
composite IFB channel audio level, i.e., pro-
gram and interrupt audio level. The meter
facilitates the rapid setting of the program
level control, as well as providing a general
indication of the channel’s signal level.
Each channel’s composite IFB audio signal
(program and interrupt audio) is sent to four
places: line output, talent amplifier output,
telephone interface 2, and monitor amplifier.
The line outputs provide electronically bal-
anced, line-level signals that interface with
external equipment via two XLR-type con-
nectors. The talent amplifier output provides
channel 1 and 2 audio, along with +22 Vdc
power on one 3-pin XLR-type connector.
Any combination of up to four Model 32 or
33s can be connected to the talent amplifier
output.
Program Inputs
The Model 2 contains four program inputs.
Each can be individually assigned to the
two IFB channels, with the ability to assign
multiple program inputs to an IFB channel.
Program signals enter the unit via four XLR-
type connectors on the back panel. The pro-
gram inputs are electronically balanced with
a nominal input impedance of 24 k ohms.
They feature low noise, low distortion, and
high common mode signal rejection. Each
program input has a trim potentiometer
associated with it. The trim pots, accessible
from the back panel, allow the nominal
+4 dBu input level to be adjusted over a
±8 dB range.
Program audio is muted whenever an inter-
rupt takes place. A sophisticated analog
switch is used to give a noise-free mute with
absolutely no clicks or pops! If desired, a
program “dim,” rather than a full mute can
be implemented by adding two resistors to
the Model 2’s circuit board.
Compressor Circuits
Each IFB channel contains a studio-
quality compressor circuit. This serves to
even out variations in the interrupt audio sig-
nals and smoothly control peak signal lev-
els. They make talent cues more intelligible