Studio Technologies IFB Plus 2007 - Manual (Page 8)

Issue 9, January 2006 Model 2 User Guide
Page 8 Studio Technologies, Inc.
displays when the standard audio mode
is selected. Even during operation in this
mode, the loop current LEDs remain active,
serving as a useful diagnostic tool. They will
display if your “standard audio signal” is
actually a telephone line!
Voice Operated (VOX) Interrupt
The Model 2 contains circuitry to allow an
audio signal to serve as both an interrupt
audio source and a control signal. This
eliminates the need for a separate push-
to-talk button or contact closure. The VOX
feature allows an audio signal from a remote
source, such as a two-way radio or tele-
phone line, to serve as the interrupt source.
The VOX function was optimized for detec-
tion of audio signals in the voice band. As
voice detection is quite tricky to perform,
great care was taken when designing this
function.
Three audio sources can serve as the VOX
input: receive audio from telephone interface
1, receive audio from telephone interface 2,
or the auxiliary audio input. The auxiliary au-
dio input is a separate line-level audio input
that serves the VOX circuit only. A 3-position
switch selects which source will be used. A
second 3-position switch selects which IFB
channel the VOX interrupt is assigned to, or
if the function is not active. The VOX function
can be assigned to only one IFB channel at
a time. Each IFB channel contains an LED
indicator light to display when a voice-
activated interrupt is taking place.
Internal Interrupt Microphone
Contained behind the Model 2’s front panel
is an internal interrupt microphone. Associ-
ated with the microphone are two switches,
allowing the internal microphone to interrupt
IFB channel 1, channel 2, or both.
Monitor Section
The Model 2 contains a simple but excel-
lent monitor section. At the core is a 4 watt
audio amplifier designed to drive an 8 ohm
(or greater) loudspeaker. Associated with
the monitor amplifier is a 3-position source
select switch and a level control. The switch
selects monitoring of IFB channel 1 or 2, as
well as having an off position. A click-free
analog switch mutes the monitor output
whenever the internal microphone or a
Model 22 or Model 24 Access Station, if in-
stalled and configured, is interrupting either
IFB channel.
Model 22 Access Station
The Model 22 Access Station provides the
capability to add up to four additional inter-
rupt locations. Model 22s are intended to be
installed at positions convenient to produc-
ers, directors, or other personnel who need
to “cue” talent and related personnel. The
unit consists of a metal chassis containing
two lighted pushbutton switches, unbal-
anced microphone and balanced line
inputs, and status and control circuitry.
The two high-quality, back-lit pushbutton
switches provide access to the two IFB
channels. The lights in the switches dis-
play when an interrupt is taking place on its
respective channel. When a channel is idle,
the light is lit dimly. An input select switch
allows connection of a Model 11A Goose-
neck Microphone or a line-level signal. The
electronically balanced line-level input al-
lows interfacing with other communications
equipment, such as an intercom system.
The Model 22 can be configured to mute
the Model 2’s monitor amplifier output. This
function will prevent acoustic feedback from
occurring when a Model 22 is located close
to the Model 2’s monitor speaker.