Revision C • 1/04
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3-8
3 Operation
digital
TELCO/CODEC MODULE OPERATION
Up to six “callers” (any remote send and receive
device like a telephone hybrid, satellite transceiver,
ISDN interface, etc.) can connect to six Telco/
Codec modules (Telco), as illustrated below.
Each Telco is set to a unique Telco ID number
(see page 2-25) and has two mono mix-minus
outputs on the Output 1 module. The mono mix-
minus outputs, also called Foldback mixes, send
a sum of one of the program or off-line buses back
to the caller—but always minus the caller’s audio.
Hence the mix-minus nomenclature, and why
there are six separate Foldback outputs.
Each mix-minus connector has two
outputs. The left output is meant for the
caller, remote talent, or a remote producer
since it has talkback superimposed over
the mono mix-minus. The right output is
a mono “clean feed” (it has no talkback).
It is used for guests or a remote site pro-
gram feed. The board operator talks to
any caller by pressing the Talkback but-
ton on that Telco module. A local Pro-
ducer can talk to any caller using a cus-
tom switch panel or a Producer Talk-
back/IFB panel (PRE99-1188).
TELCO FOLDBACK MIX
The Telco Foldback mix source, indicated by its
“winking” assignment button on each Telco mod-
ule, is derived from a program or off-line bus. The
bus used is determined by which buses are as-
signed and by whether an Auto-Foldback button
is on. If it is, then the Telco’s state (module On or
Off) also affects which bus is the Foldback source.
The program bus Foldback feeds are derived
post-switch and post-fader, but the off-line bus
feeds are pre-switch and either pre-fader or post-
fader (determined by Session module DIP switch
6, see page 2-33). The Telco modules have a sepa-
rate DIP switch (see page 2-25) active when pre-
fader is selected on the Session module. This al-
lows the Telco modules to be post-fader even when
Universal and RLS modules are pre-fader.
Note:
When a Telco is set for pre-fader O/L feed,
this setting forces the active Send and Utility buses
to also be pre-fader, when the module is off.
Auto-Foldback On
When the AUTO F/B button is lit, as shown
below, that Telco’s Foldback mix automatically
switches between the assigned program bus when
the module is On, and the assigned off-line bus
when the module is Off, using this bus priority:
Foldback Sources
FOLDBACK SOURCE
since AUTO F/B is lit
& module is Off
FOLDBACK SOURCE
since AUTO F/B is lit
& module is On
Output
(Receive from network)
Input
(Send to network)
Telos Zephyr
Output 1 Module
Telco/Codec Module
(set as Telco #1)
Typical Telco/Codec
