Orban OPTIMOD-FM 8600, Operating Manual

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INTRODUCTION ORBAN MODEL 8600
to waveform discontinuity). If you have some presets with
LLH
ARD
bass
clipper mode and some without, switching between these presets is likely
to cause clicks unless you do it during silence. However, these clicks will
never cause modulation to exceed 100%.
One of the essential differences between the
H
ARD
and
LLH
ARD
bass clip-
per modes is that switching between
H
ARD
and
M
ED
does not change de-
lay and is therefore less likely to cause audible clicks.
•
Ultra-low latency processing uses a separate, parallel processing structure and is
invoked by recalling any “UL” preset. This structure operates simultaneously with
other code, so, unlike the similar structure in Orban’s Optimod 8300, it does not
require a code re-load and does not cause a gap in programming.
The only way to create an ultra-low latency user preset is to start with a
“UL” factory preset and then edit that preset. “UL” user presets cannot
be directly converted to low latency or optimum latency presets because
the preset customization controls are different—UL presets have fewer
available controls because of the difference in processing structure.
UL presets are the closest emulations of Optimod 8200 processing availa-
ble in the 8600. These presets differ from Optimod 8200 processing in
two main ways: (1) the 8600 UL presets still use the 8600’s stereo en-
hancement, equalization section, advanced-technology AGC, composite
limiter, and multiplex power controller, and (2) the 8600 UL presets use
anti-aliased clippers operating at 256 kHz sample rate.
Some talent moving from an analog processing chain will require a learning period
to become accustomed to the voice coloration caused by “bone-conduction” comb
filtering. This is caused by the delayed headphone sound’s mixing with the live voice
sound and introducing notches in the spectrum that the talent hears when he or she
talks. All digital processors induce this coloration to a greater or lesser extent. For-
tunately, it does not cause confusion or hesitation in the talent’s performance unless
the delay is above the psychoacoustic “echo fusion” (Haas) threshold of approxi-
mately 20 - 25 ms and the talent starts to hear slap echo in addition to frequency re-
sponse colorations.
Low-Delay Monitoring
The 8600’s analog outputs can be switched to provide a low-delay monitoring
feed (see step 15 on page 2-39). This feed has no peak limiting and thus cannot
drive a transmitter, but its 3 to 8 ms delay is likely to be more comfortable to talent
than the 18 ms delay of the full processing chain because of less bone conduction
comb filtering.
If the talent relies principally on headphones to determine whether the station is on
the air, simple loss-of-carrier and loss-of-audio alarms should be added to the sys-
tem. The 8600 can be interfaced to such alarms through any of its eight its GPI re-
mote control inputs, cutting off the low-delay audio to the talent’s phones when an
audio or carrier failure occurs.
The front panel headphone jack provides output matching the Analog Output, ex-
cept that it is always de-emphasized (even if the Analog Output is set with
preemphasis).