TELOS 2101 USER’S MANUAL
PART IV
THE STUDIO INTERFACE & ADDITIONAL HYBRIDS
IV-23
SECTION 1 – STUDIO INTERFACE INSTALLATION
Example 2: Using a utility mixer
A general purpose utility mixer is used to record interviews off the telephone line
using a single hybrid. The mixer’s main bus is fed to the recording device. Both the
microphone and the hybrid will be brought up on the faders so the interview can be
recorded.
Again, we will use a second buss to feed the hybrid. In this case, we will take the
Aux 1 output to feed the hybrid. We will turn up Aux 1 for the microphone but we
will make sure it is turned fully off for the input channel with the caller audio.
Mic Preamp
AUX 1
AUX 2
OUTPUT
FROM
HYB #1
LEFT OUTPUT
RI GHT OUTPUT
AUX 1 OUT
AUX 2 OUT
TO HYB #1 "IN"
UTILITY
MIXER
Mic1
Caller
NOTE:
This must be turned
down or AUX 1 will no
longer be a mix-minus!
A simple mix-minus using a spare bus.
Why do I need a mix-minus?
Adaptive hybrids, commonly used in broadcast applications since Telos pioneered
the technology, work by comparing the audio sent down the line to the audio received
back from the line. The system then adjusts itself to minimize send audio in the audio
coming back (i.e. minimizes leakage). Thus the audio fed to the hybrid is, in effect, a
reference signal. If the audio sent into the hybrid contains the caller audio (the audio
we want) then there is no reference signal and the system cannot do its job.