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Section 13.9 Output Control
MASTER
audio output is represented by its own control group in the
Audio
, and regulates sound sent to
both physical AUDIO OUT connectors and the MIX and AUX NDI video outputs.
Hint: Shift + double click Volume knobs to restore their default values (0 dB).
Master settings take effect downstream from all audio sources.
13.9.1 Headroom Notes
In digital audio systems, signal levels that exceed maximum values are uniformly assigned the maximum
value, a condition known as “clipping”. Clipping inevitably results in annoying audible issues. Worse,
over-modulation that may not be apparent while listening during live production may nonetheless appear
in recorded files. This is often true even when levels
appear
to be below the ceiling level (0 dBFS, the
maximum allowable digital level).
Hint: AV-HLC100 notifies you when clipping has occurred by temporarily turning the Audio Mixer label
for the problem channel red.
Due to this problem, digital audio system designs customarily allow substantial ‘headroom’ above the
benchmark ‘alignment level’, making over-modulation much less likely. Often this allowance seems high
to those familiar with analog audio systems; headroom levels between 18 and 24 dB are not uncommon
in professional digital audio realms.
AV-HLC100’s
Record
level defaults to -20 dBFS (set in the
Record Configuration
panel), approximating
typical professional practice. This has no impact on levels at the system’s audio outputs, but all but
ensures clipping in recorded files will be avoided. Advanced users can thus record files conforming to
regional standards or personal preference, substantially reduce the possibility of audio clipping in
recorded files, and even adjust the level on the fly if necessary.
The main point to remember from all of this is that for digital audio recording “less is often more”. When
it comes to levels, by all means go as high as necessary – but it’s equally practical to go no higher than
necessary.
Hint: The Audio Mixer also provides Compressor/Limiters for each input and output. These can also
be invaluable in defeating clipping due to over-modulation.
