C
OMREX
C
ORPORATION
36
STAC Product Manual
37
Callers on both hybrids will hear audio applied to the
Send Input
on the
STAC mainframe. Audio from the caller(s) on Hybrid 1 is available on the
Hybrid 1 Output
port. Audio from the caller(s) on Hybrid 2 is available on
the
Hybrid 2 Output
port. Audio from callers on both hybrids is available
on the
Aux Output
port. Hybrid 1 caller audio is also routed to Hybrid 2
and Hybrid 2 caller audio is routed to Hybrid 1. This allows callers to hear
each other as well as the studio-generated audio. This also allows a single
“mix-minus” (audio without any callers) to be applied to the
Send Input
.
This function cannot be defeated – i.e. callers always hear the audio from
the other hybrid, and two separate “mix-minuses” are not supported. If
this function is essential, see
C
ONNECTION
OF
AN
E
XTERNAL
H
YBRID
on page 42.
Each hybrid is technically capable of supporting two calls simultaneously.
This is done by simply summing the lines together in a “button mashing”
fashion. If there are differences in level between these lines, this scenario
may not perform very well. For optimal hybrid performance, we recom-
mend one call per hybrid.
Using Digital Signal Processing (DSP) technology and firmware, the inter-
face between a standard analog POTS line and your audio equipment will
result in superior quality audio. The primary function of STAC hybrids is to
maximize the null by maximizing the separation of send and caller audio.
Both hybrids provide >55 dB null between 250 Hz to 3.5 kHz.
AGC normalizes the gain of caller audio, augmenting the level of soft
callers, and attenuating the level of loud callers. This helps provide more
uniform caller audio levels at the caller output of the hybrid. The AGC
threshold is -50 dBm. The AGC works to achieve an average caller level of
-30 dBm from the telephone circuit.
STAC’s
Auto Mix-Minus
creates a mix-minus for the hybrids when one is
not available from the audio console. See the
A
BOUT
M
IX
-M
INUS
section on
page 38 for further information.
Caller control, also known as ducking, attenuates the caller input audio
when send audio is present. The purpose of this attenuation is to allow the
talent to dominate their conversation with the callers. The amount of caller
control (attenuation) applied to the caller audio is selectable from
0 to 18 dB, in 6 dB increments. For details, see
DIP S
WITCHES
on page 12.
T
ELEPHONE
S
EPARATION
/N
ULL
A
UTOMATIC
G
AIN
C
ONTROL
A
UTOMATIC
M
IX
-M
INUS
C
ALLER
C
ONTROL
