OPTIMOD-FM INTRODUCTION
1-21
which most talent finds uncomfortable and distracting. However, the normal delay
through the 8400 (from input to FM outputs) is about 20 ms when
Hard or Medium bass
clipping is selected, as it is in all factory presets other than those with “LL” (“low la-
tency”) in their names. A 20 ms delay is comfortable for most talent because they do not
hear echoes of their own voices in their headphones. Consequently, customers can ordi-
narily replace an older processor with the 8400 with no studio wiring changes. Moreover,
off-air cueing of remote talent is routine.
A low-delay option is available, which reduces input/FM-output delay to 15 ms. The
trade-off for this reduction is slightly lower performance than the 8400’s full look-ahead
processing offers.
You can invoke the low-delay mode by setting the BassClipMode control (in
the
Clippers page of Advanced Control) to LLHard, or by recalling a preset
with “LL” as part of its name. (“LL” stands for “low latency.”)
LLHard differs in two ways from the normal Hard mode of the bass clipper:
•
LLHard automatically defeats the compressor lookahead. (This action is
functionally equivalent to setting the
Lookahead control to Out, except
that it reduces input/output delay by 5 ms).
•
LLHard prevents the bass clipper from switching to Medium mode when-
ever speech is detected. By constraining the system in these ways, it
ensures that the delay is always 15 ms.
Switching the
BassClipMode to LLHard (from any other mode) removes five
milliseconds of delay from the signal path. Switching can cause audible
clicks, pops, or thumps (due to waveform discontinuity) if it occurs during
program material. If you have some presets with
LLHard 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
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 8400’s analog outputs can be switched to provide a low-delay monitoring feed. This
feed has no peak limiting and thus cannot drive a transmitter, but its 5-10ms delay may
be more comfortable to talent than the 20 ms delay of the full processing chain because of
less bone conduction comb filtering.
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 in-
duce this coloration to a greater or lesser extent. Fortunately, it does not
cause confusion or hesitation in the talent’s performance unless the delay is
above the psychoacoustic “echo fusion” (Haas) threshold of approximately
20 ms and the talent starts to hear slap echo in addition to frequency re-
sponse colorations.
To Next Page
Loading...
