Optimod-AM 9400 V1.2 Operating Manual - Orban

3-44
OPERATION ORBAN MODEL 9400
One of the essential differences between the HARD and LLHARD bass clipper
modes is that switching between HARD and MED does not change delay
and is therefore less likely to cause audible clicks.
The HARD CLIP SHAPE control (in Advanced Control) offers further control
over the sound of the HARD and LLHARD modes. See page 3-44.
MEDIUM uses more sophisticated signal processing than HARD to reduce distortion
substantially.
SOFT uses the most sophisticated look-ahead signal processing to reduce distortion
further. Using SOFT adds an additional 18 ms of delay to the processing.
MEDIUM and SOFT are not available in Low Latency mode. The bass clipping
is always HARD, but the HARD CLIP SHAPE control is still available to
“soften” the clipping.
Speech Bass Clip set the threshold of the bass clipper when the 9400 detects the
presence of speech. It is usually set to “0” to prevent the bass clipper from adding
distortion on speech.
Clip Shape (“Bass Clip Shape”) allows you to change shape of the knee of the Input/Output
gain curve of the bass clipper. The “knee” is the transition between no
clipping and flat topping. A setting of “0” provides the hardest knee. “10” is the
softest knee, where the transition starts 6 dB below BASS CLIP THRESHOLD setting and
occurs gradually. The factory default setting is “7.6.”
HF CLIP (“High Frequency Clipper Threshold”; AM chain only) sets the threshold of
the multiband clipper in band 5 with reference to the final clipper threshold, in dB.
This clipper helps prevent distortion in the final clipper when the input program material
contains excessive energy above 3 kHz.
The Band 5 multiband clipper operates at 256 kHz and is fully anti-aliased.
Final Clip (“Final Clip Drive”) adjusts the level of the audio driving the back-end
clipping system that OPTIMOD-AM uses to control fast peaks. This control primarily
determines the loudness / distortion trade-off.
Turning up the FINAL CLIP control drives the final clipper and overshoot compensator
harder, reducing the peak-to-average ratio, and increasing the loudness on the air.
When the amount of clipping is increased, the audible distortion caused by clipping
also increases. Although lower settings of the FINAL CLIP control reduce loudness,
they make the sound cleaner.
If the RELEASE control is set to its faster settings, the distortion produced by the
back-end clipping system will increase as the MULTIBAND DRIVE control is advanced.
The FINAL CLIP DRIVE and/or the MULTIBAND LIMIT THRESHOLD controls may have to be
turned down to compensate. To best understand how to make loudness / distortion
trade-offs, perhaps the wisest thing to do is to recall a factory preset and then to adjust
the LESS-MORE control to several settings throughout its range. At each setting
of the LESS-MORE control, examine the settings of the MULTIBAND DRIVE and
MULTIBAND LIMIT THRESHOLD controls. This way, you can see how the factory pro-