AEV ITB201 - dual telephone hibryd
AEV Broadcast srl - via della Tecnica 33, 40050 Argelato Bologna ITALY
www.aev.eu
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Telephone hybrid
A telephone hybrid is a system that provide the connection between a telephone line and
an audio equipment. Actually, this is not a simple connection since the telephone line
characteristics require special techniques to ensure good audio quality and high
immunity to interference. The frequency response of a normal telephone line is set between
100 Hz and 3-4 KHz in order to guarantee an acceptable reproduction of the human voice. A
telephone hybrid must have a much wider bandwidth, in order to adapt itself to the quality of
any line and to avoid further limitations to the system. Unfortunately telephone lines suffer
often of intense disturbances, noise, crackling, fading etc. Furthermore they are often sources
or conductors of static charge and overvoltage, that are able to destroy circuits which have
been imprudently connected to them. In addiction, the resistive and capacitive behaviour of
lines is not uniform, and thus barely repeatable, and clearly the transmitted audio quality will
vary with time. It is therefore necessary to take particular care in the design of line-audio
interfaces in order to avoid significant degradation of the bandwidth or rejection of induced
interference. The interface must also ensure complete electrical isolation between theline
section and that connecting to the audio equipment.
Another problem arises during a telephone connection between a remote correspondent
and an interviewer or DJ; the DJ’s voice will be transmitted down the telephone line and,
since the same line is used for transmission and reception, will be received again with
delay with respect to the original. It will be re-amplified and looped back resulting in
whistles and Larsen effects. Antilocal circuits are fitted to remedy this by identifying those
audio components which tend to enter into the loop and eliminating only the part which
re-enters. This is particularly necessary for Meetings
General Features
AEV ITB-201 MKII is a studio telephone hybrid. It is designed in a 19", 1 unit rack mount.
ITB-201 MKII allows the connection of 2 phone lines individually commutable during
transmission. By means of an extra telephone, to be plugged into 2 special connectors, you
may call or receive on both lines. The calls are visualized by leds and announced by a ringer.
ITB-201 MKII was specially designed to solve all interfacing problems between lines and any
Mixer having no telephone module. It allows to call or receive private communications or to
pass them over to the antenna without having to use additional headsets or microphones.
It is easy to install and requires no special instruments. ITB-201 MKII has an available output
to record phone conversation both privately and in antenna.
Installation
AEV ITB-201 MKII telephone hybrid has been designed and manufactured to conform to
urrent safety standards. The unit should only be installed by competent personnel and in
compliance with operator safety requirements and the environmental specification.
Great care should be taken in making earth and ground connections to the unit and
associated equipment. As for any electronic apparatus, adequate ventilation for cooling must
be ensured in order to guarantee operating temperatures within the limits defined in the
Technical Specifications section.
This is particularly important in the case of rack mounting or installation in confined or poorly
ventilated locations. It is advisable to leave a space between each unit and adjacent units
