Stereo Enhancer Controls - Orban OPTIMOD-FM 5500 Operation Manual

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OPERATION

Stereo Enhancer Controls

PH-ROTATE ("Phase Rotator") is not a stereo enhancer control. It determines if the
phase rotator will be in-circuit. The purpose of the phase rotator is to make voice
waveforms more symmetrical. This can substantially reduce distortion when they are
peak limited by the 5500's back end processing.
In most cases, we recommend that the phase rotator be left active. However, be-
cause it can slightly reduce the clarity and definition of program material, you can
defeat it if you are operating the 5500 conservatively and not attempting to achieve
very high on-air loudness.
You have somewhat more leeway than you do in older Orban FM processors like the
8200 because the 5500's new distortion control will work to help prevent audible
speech distortion even when the phase rotator is switched out.
The stereo enhancer emulates the Orban 222 analog stereo enhancer. The enhancer
has gating that operates under two conditions.

The two stereo channels are close to identical in magnitude and phase.
In this case, the enhancer assumes that the program material is actually
mono and suppresses enhancement to prevent the enhancement from
exaggerating the undesired channel imbalance.

The ratio of L–R/L+R of the enhanced signal tries to exceed the threshold set by
the L-R/L+R Ratio Limit control.
In this case, the enhancer prevents further enhancement in order to pre-
vent excess L–R energy, which can increase multipath distortion.
The stereo enhancer has the following controls. Note that "advanced" controls are
accessible only from 5500 PC Remote software.
ENH AMT sets the maximum spatial enhancement. When set to O
stereo enhancer.
RATIO LMT ("L–R/L+R Ratio Limit") sets the maximum amount of enhancement to
prevent multipath distortion. However, if the original program material exceeds this
limit with no enhancement, the enhancer will not reduce it.
Stereo Enhancer Controls
Basic/Full Modify Name
ENH AMT
RATIO LMT
Advanced Name
Stereo Enhancer Amount
L–R/L+R Ratio Limit
Table 3-3: Stereo Enhancer Controls
ORBAN MODEL 5500
, it bypasses the
UT
Range
0.0 ... 10.0
70 ... 100%