Connecting telephone lines – Studio Technologies IFB Plus 2005 User Manual

Page 12

Issue 8, December 2005

Model 2 User Guide

Page 12

Studio Technologies, Inc.

Model 2’s sonic quality is as good as many
audio consoles, tape recorders, etc. As an
example, the frequency response from pro-
gram input to line output is better than
±0.5 dB from 20 Hz to 20 kHz. This makes
using one of the IFB channels as a four
input, one output audio source selector for
an uplink application completely valid. Let
the Model 2 become a useful part of your
facility’s “bag of tricks!”

Connecting Telephone Lines

Words of Caution: As with any product,
installing the Model 2 requires a safety-first
approach.

Never install telephone wiring during a light-
ning storm. Never install telephone jacks in
wet locations unless the jack is specifically
designed for wet locations. Never touch
non-insulated telephone wires or terminals
unless the telephone line has been discon-
nected at the network interface. Use caution
when installing or modifying telephone lines.

The Model 2 contains two telephone inter-
faces which can be individually configured
to allow connection to a telephone line or to
a standard audio signal. A telephone line is
designated as such if it has a DC bias cur-
rent associated with it. This type of signal is
sometimes referred to as a “wet” signal. A
standard audio signal is one that is isolated
from any source of DC voltage. Some fax
adapters associated with cellular telephones
provide this type of “telephone” line. A stan-
dard audio signal is sometimes referred to
as a “dry” signal. While this sounds confus-
ing, contemporary applications sometimes
refer to both types of signals as “telco.”
To a large production vehicle that pulls up
to do a two-week golf tournament, a telco
line is one provided by the local telephone
company on an RJ11 jack. To a mobile ENG
vehicle, a telco signal might come from a

cellular telephone which in most cases is a
standard audio signal.

Here is a review of the important features of
the Model 2’s telephone interfaces:

Interface 1
• Telephone line or standard audio mode
select switch on back panel

• Used to receive audio only

• Receive audio used as program and/or
VOX

source

• Front panel ±8 dB receive level trim pot

• Switch allows manual off-hook and
hang-up

(telephone

line

mode)

• Auto disconnect upon break in loop
current (telephone line mode)

• Operating mode and loop current status
LEDs

Interface 2
• Telephone line or standard audio mode
select switch on back panel

• Used to receive or send audio