Aphex Studio Dominator 700 - Model 704 - W; Pre;De-Emphasis and Lowpass Fltr

quality of the sound.
Stereo program distribution via satellite is often matrixed
to allow simple one-channel recovery of the monaural component
for radio and television stations not capable of stereo
transmission. Simple de-matrixlng is then performed at
two-channel down-links to recover the stereo. One common
problem which occurs with satellite audio distribution is
sibilance or high frequency distortion due to accidental carrier
overdeviation. This happens because inefficient or nonexistent
modulation limiting at the uplink transmitter. In some cases,
program originators have had to reduce the audio levels laid on
tape, reduce the send levels, or incorporate a de-esser to
compensate for this distortion. The matrixed studio Dominator
can eliminate these problems by maintaining undistorted well
modulated stereo satellite carriers with hiqhly transparent
audio fidelity.
The preferred point to insert the Studio Dominator is, of
course, at the satellite uplink transmitter. However, a program
producer having no technical control over the contracted uplink
can be reasonably assured of cleaner satellite transmission if
the matrixed Studio Dominator is used at the studio for
protection limiting ahead of the outgoing feed to the satellite
uplink station.
7.2 Model 703 - With Pre- and De-Emphasis
Limiting according to an equalization curve such as 75
microsecond pre-emphasis can be accomplished by incorporating
this card. Internal input and output patch points are accessed
by the card, and the pre-emphasis is inserted ahead of limiting.
Selectable de-emphasis is provided after limiting to restore
flat response below threshold if required.
This option is shipped with 75 microsecond pre-emphasis as
standard. A different equalization curve can be obtained by
changing a capacitor or resistor. 50 microsecond pre-emphasis
for European broadcasting can be shipped upon request. .
Because the audio dynamics become radically different when
FM broadcast pre-emphasis is incorporated, the limiter must be
modified in several ways to most efficiently accommodate the
signal. The following changes are made at the factory when
Model 702 is ordered.
1. The ALT generator has an additional timing resistor
included.
2. The high frequency limiters are given a slower attack
time.
3. The tligh frequency limiters are given a faster release
time.
4. The final summing limiter is given slig~tly more
clipping.
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